Element, and terahertz camera system using the same

Abstract

In an antenna array including a first antenna, a second antenna, a third antenna, a fourth antenna, and a fifth antenna, the second antenna, the first antenna, and the third antenna are arranged in this order in a first direction, and the fourth antenna, the first antenna, and the fifth antenna are arranged in this order in a second direction. A conductor layer of the second antenna is connected to a conductor layer of the first antenna via a first coupling line extending in the first direction, the conductor layer of the first antenna is connected to a conductor layer of the third antenna via a second coupling line extending in the first direction, a conductor layer of the fourth antenna is connected to the conductor layer of the first antenna via a third coupling line extending in the second direction, and the conductor layer of the first antenna is connected to a conductor layer of the fifth antenna via a fourth coupling line extending in the second direction.

Description

Technical Field

[0001] This invention relates to an element and a terahertz camera system using the element. Background Technology

[0002] Oscillators that integrate resonators and components with electromagnetic wave gain for terahertz waves are considered current-injected light sources for generating terahertz waves. Oscillators integrating resonant tunneling diodes (RTDs) and antennas are expected to operate in a frequency range of approximately 1 THz at room temperature.

[0003] PTL 1 describes a terahertz wave antenna array in which multiple oscillators, including an RTD and an antenna, are deployed on the same substrate. In the antenna array of PTL 1, microstrip lines are provided as coupling lines to synchronize the phases of the multiple oscillators.

[0004] Citation List

[0005] Patent documents

[0006] PTL 1: Japanese Patent Publication No. 2014-200065

[0007] Non-patent literature

[0008] NPL 1: J. Appl. Phys., Vol. 47, No. 6 (2008), pp. 4375-4384

[0009] NPL 2: J. Appl. Phys., Vol. 103, 124514 (2008) Summary of the Invention

[0010] Technical issues

[0011] In PTL 1, sufficient research has not yet been conducted on satisfying phase matching conditions between multiple oscillators, etc.

[0012] In view of the above problems, the object of the present invention is to provide an advantageous antenna array structure.

[0013] Solution to the problem

[0014] One aspect of the present invention is an element comprising an antenna array in which multiple antennas are deployed. Each antenna includes a first conductor layer, a semiconductor layer electrically connected to the first conductor layer and generating or detecting terahertz waves, a second conductor layer electrically connected to the semiconductor layer and opposed to the first conductor layer via the semiconductor layer, and a dielectric layer located between the first and second conductor layers. The antenna array includes a first antenna, a second antenna, a third antenna, a fourth antenna, and a fifth antenna. The second, first, and third antennas are arranged in this order in a first direction. The fourth, first, and fifth antennas are arranged in this order in a second direction intersecting the first direction. The second conductor layer of the second antenna is connected to the second conductor layer of the first antenna via a first coupling line extending in the first direction. The second conductor layer of the first antenna is connected to the second conductor layer of the third antenna via a second coupling line extending in the first direction. The second conductor layer of the fourth antenna is connected to the second conductor layer of the first antenna via a third coupling line extending in the second direction. The second conductor layer of the first antenna is connected to the second conductor layer of the fifth antenna via a fourth coupling line extending in the second direction.

[0015] Advantages of the invention

[0016] According to the present invention, an advantageous antenna array structure is provided. Attached Figure Description

[0017] Figure 1A This is a top schematic diagram showing element 10 according to the first embodiment.

[0018] Figure 1B This is a top schematic diagram showing a modification of element 10 according to the first embodiment.

[0019] Figure 2 This is a schematic diagram illustrating the construction of element 10 according to the first embodiment.

[0020] Figure 3A This is a schematic cross-sectional view of element 10 according to the first embodiment.

[0021] Figure 3B This is a schematic cross-sectional view of element 10 according to the first embodiment.

[0022] Figure 4 This is a plan view of the second conductor layer of element 10 according to the first embodiment.

[0023] Figure 5A This is a diagram illustrating the effect of element 10 according to the first embodiment.

[0024] Figure 5B This is a diagram illustrating the effect of element 10 according to the first embodiment.

[0025] Figure 5C It is a graph illustrating the effect of element 10 according to the first embodiment.

[0026] Figure 6A This is a diagram showing element 20 according to the second embodiment.

[0027] Figure 6B This is a diagram showing element 20 according to the second embodiment.

[0028] Figure 7A This is a top schematic diagram showing element 20 according to the second embodiment.

[0029] Figure 7B This is a schematic cross-sectional view showing element 20 according to the second embodiment.

[0030] Figure 8A This is a diagram showing element 30 according to the third embodiment.

[0031] Figure 8B This is a diagram showing element 30 according to the third embodiment.

[0032] Figure 9A This is a diagram showing element 40 according to the fourth embodiment.

[0033] Figure 9B This is a diagram showing element 40 according to the fourth embodiment.

[0034] Figure 10 This is a diagram illustrating a terahertz camera system according to a fifth embodiment.

[0035] Figure 11A This is a top schematic diagram showing element 50 according to the sixth embodiment.

[0036] Figure 11B This is a top schematic diagram showing element 50 according to the sixth embodiment.

[0037] Figure 11C This is an enlarged top view showing element 50 according to the sixth embodiment.

[0038] Figure 11D This is a top schematic diagram showing a modification of element 50 according to the sixth embodiment.

[0039] Figure 12A This is a schematic cross-sectional view showing element 50 according to the sixth embodiment.

[0040] Figure 12B This is a schematic cross-sectional view showing element 50 according to the sixth embodiment.

[0041] Figure 12C This is a schematic cross-sectional view showing element 50 according to the sixth embodiment.

[0042] Figure 13A This is a top schematic diagram showing element 60 according to the seventh embodiment.

[0043] Figure 13B This is a top schematic diagram showing element 70 according to the seventh embodiment.

[0044] Figure 14A This is a top schematic diagram showing the elements according to the eighth embodiment.

[0045] Figure 14B This is a top schematic diagram showing the elements according to the eighth embodiment.

[0046] Figure 15A This is a top schematic diagram showing the elements according to the eighth embodiment.

[0047] Figure 15B This is a top schematic diagram showing the elements according to the eighth embodiment.

[0048] Figure 16A This is a top schematic diagram showing the elements according to the eighth embodiment.

[0049] Figure 16B This is a top schematic diagram showing the elements according to the eighth embodiment.

[0050] Figure 17A This is a top schematic diagram showing the elements according to the eighth embodiment.

[0051] Figure 17B This is a top schematic diagram showing the elements according to the eighth embodiment.

[0052] Figure 18A This is a top schematic diagram showing the elements according to the eighth embodiment.

[0053] Figure 18B This is a top schematic diagram showing the elements according to the eighth embodiment.

[0054] Figure 19A This is a top schematic diagram showing the elements according to the eighth embodiment.

[0055] Figure 19B This is a top schematic diagram showing the elements according to the eighth embodiment.

[0056] Figure 20A This is a top schematic diagram showing the elements according to the eighth embodiment.

[0057] Figure 20B This is a top schematic diagram showing the elements according to the eighth embodiment.

[0058] Figure 21This is a schematic diagram illustrating the elements according to the eighth embodiment. Detailed Implementation

[0059] Embodiments will be described with reference to the accompanying drawings. In the following description, element 10 will be described as being used as a transmitter; however, element 10 can also be used as a receiver. Here, terahertz waves refer to electromagnetic waves with a frequency range of 10 GHz or higher and 100 THz or lower, more preferably, 30 GHz or higher and 30 THz or lower.

[0060] In the description of each embodiment, the description of components that are the same as in another embodiment may be omitted. Each embodiment can be modified as needed or combined with another embodiment as needed.

[0061] (First Embodiment)

[0062] Reference Figure 1A and 2 The following describes element 10 according to this embodiment, up to 5C. Reference will be made to... Figure 1A and 2 Sections 4 describe the construction of element 10. Figure 1A This is a schematic diagram of the top of component 10 when viewed from above. Figure 1A This can be viewed as a top view showing element 10. Figure 1A The X, Y, and Z directions are shown. The X and Y directions only need to intersect each other. Figure 1A In this plane, the X and Y directions are perpendicular to each other. The X and Y directions lie within a single plane. The Z direction is perpendicular to both the X and Y directions and is also called the upward direction. Figure 2 This is a perspective view that schematically shows the appearance of element 10. Figure 3A It is along Figure 1A A schematic cross-sectional view of element 10 taken by line A-A' in the diagram. Figure 3B It is along Figure 1A A schematic cross-sectional view of element 10 taken by line B-B' in the diagram. Figure 4 This is a schematic plan view showing the second conductor layer of element 10.

[0063] like Figure 1A and 2 As shown in Figures 4 to 4, the length of the components of element 10 (i.e., substrate 113, dielectric layer 104, semiconductor layer 115, etc.) in the lamination direction of the components is referred to as thickness or height. The side on which the dielectric layer 104 and semiconductor layer 115 are located relative to the substrate 113 is referred to as the upper side.

[0064] Reference Figure 1AElement 10 is described. Element 10 is a device for oscillating or detecting terahertz waves at a frequency of f THz and is made of semiconductor material. Multiple antennas are deployed in element 10. In this embodiment, element 10 includes an antenna array in which nine antennas 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h, and 100i are arranged in a 3×3 matrix.

[0065] The construction of the antennas will be described. Each of antennas 100a to 100i has a similar construction. In the following description, the construction of antenna 100a will be described in detail, and detailed descriptions of components in other antennas 100b to 100i that are similar to the components of antenna 100a will be omitted. In the description, the letter corresponding to each antenna is added after the reference numerals of the components of each of antennas 100a to 100i. For example, the components of antenna 100a in the second conductor layer 103 will be described in relation to the second conductor layer 103a.

[0066] Antenna 100a serves as a resonator for causing terahertz waves to resonate and as a radiator for transmitting or receiving terahertz waves. The antennas can be deployed at intervals less than or equal to the wavelength of the terahertz wave to be detected or generated, or an integer multiple of that wavelength.

[0067] like Figure 3A As shown, substrate 113, first conductor layer 106, and second conductor layer 103a are laminated in this order. Between the first conductor layer 106 and the second conductor layer 103a, dielectric layers 1042 and 1041 are arranged in this order from the first conductor layer 106 side. Similar to antennas 100a to 100i, each of the second conductor layers 103a to 103i has a similar structure. A third conductor layer 110ab is disposed between the second conductor layers 103a and 103b. Similarly, in antennas 100a to 100i, third conductor layers 110bc, 110cf, etc. are included. The third conductor layer 110bc is disposed between the second conductor layers 103b and 103c. In the following description, for example, the conductor layer connecting antennas 100x and 100y is referred to as conductor layer 110xy, conductor layer 110yx, etc. This is not limited to conductor layers; it also applies to coupling layers, etc.

[0068] Antenna 100a has at least a first conductor layer 106, a second conductor layer 103a, and a semiconductor layer 101a disposed between the first conductor layer 106 and the second conductor layer 103a. Semiconductor layer 101a is a resonant tunneling diode (RTD), which will be described in detail later, and is also referred to as RTD 101a or active layer 101a. Hereinafter, semiconductor layer 101a may also be referred to as RTD 101a. Antenna 100a also includes a semiconductor layer 115a, an electrode 116a for ohmic bonding, and a conductor 117a for connecting the second conductor layer 103a and the RTD 101a. Coupling line 109ab includes a third conductor layer 110ab. Bias line 111x2 is disposed between the third conductor layer 110ab and the first conductor layer 106. Bias line 111x2 is located between dielectric layer 1042 and dielectric layer 1041.

[0069] exist Figure 3B In the middle, the bias line 111y2, etc., are deployed in conjunction with... Figure 3A The bias lines 111x2 shown are deployed in the same layer. The bias lines 111y2 form lines 108g1 and 108d2. The second conductor layer 103a is connected to the second conductor layer 103b via conductor 107g1, lines 108g1, lines 108d2, and conductor 107d2. Figure 2 As shown, the bias line 111y2 is electrically connected to the bias circuit 120. The bias circuit 120 is also called the power supply circuit. The first conductor layer 106 is as follows: Figure 2 The grounding is shown in the diagram. (As shown in the diagram...) Figure 3A and 3B As shown, the layer including the first conductor layer 106 can be referred to as the first wiring layer, the layer including the bias line 111 can be referred to as the second wiring layer, and the layer including the second conductor layer 103 and the third conductor layer 110 can be referred to as the third wiring layer. The conductors included in each wiring layer can also be considered to be at the same level. Level refers to the height from the surface of the substrate 113.

[0070] Figure 4 A schematic diagram of a pattern comprising a second conductor layer 103 and a third conductor layer 110 at the same level is shown. An element having multiple antennas 100 will be described here.

[0071] To increase the antenna gain of element 10, it is considered to deploy multiple antennas 100. As described above, RTD 101 is deployed in each antenna 100. When mutual injection-locking is performed in each antenna 100, the antenna gain increases. To synchronize the multiple antennas 100 with each other, a coupling line is needed to couple adjacent antennas. Here, this coupling line is also referred to as a coupling wire.

[0072] To date, the coupling line has not been studied in detail. Specifically, when two adjacent antennas in an antenna array are connected by a coupling line, it is difficult to satisfy the phase matching condition in either or both of the horizontal (magnetic field direction or H-direction) and vertical (electric field direction or E-direction) directions. Therefore, as the number of antennas increases, injection-locking becomes insufficient in either the vertical or horizontal direction, and the increase in gain decreases. Furthermore, the improvement in directivity is less than expected. Thus, it is impossible to efficiently generate and detect terahertz waves using antenna arrays.

[0073] Reference Figure 4 The coupling lines of multiple antennas 100 are described. First, the coupling of the multiple antennas 100 in the X direction will be described. Antenna 100e is coupled to antenna 100f via coupling line 109ef. The coupling of the antennas in the X direction will be described. Antenna 100e is coupled to antenna 100f via coupling line 109ef and to antenna 100d via coupling line 109de. Antenna 100h is coupled to antenna 100i via coupling line 109hi and to antenna 100g via coupling line 109gh. Antenna 100b is coupled to antenna 100c via coupling line 109bc and to antenna 100a via coupling line 109ab. Figure 4 In this configuration, each antenna is directly connected to a corresponding coupling line in the coupling line, and can also be connected via capacitive coupling. Here, the X-direction is the vertical direction, the direction of the electric field, i.e., the E-direction.

[0074] Next, the coupling of multiple antennas 100 in the Y direction will be described. The coupling of antennas 100 in the Y direction is performed via coupling lines 109fi, 109cf, 1091he, 1091eb, 1092he, 1092eb, 109dg, and 109ad. Coupling line 1091he couples coupling line 109hi to coupling line 109ef, and coupling line 1091eb couples coupling line 109ef to coupling line 109bc. Coupling line 1092he couples coupling line 109gh to coupling line 109de, and coupling line 1092eb couples coupling line 109de to coupling line 109ab.

[0075] When focusing on antenna 100e, the structure will be described as follows. For antenna 100e, antennas 100f and 100d are deployed adjacent to each other on both sides of antenna 100e in a first direction (vertical direction). Antenna 100e is connected to antenna 100f via a coupling line 109ef extending in the first direction (vertical direction), and connected to antenna 100d via a coupling line 109ed extending in the first direction (vertical direction). Similarly, antennas 100h and 100b are deployed adjacent to each other on both sides of antenna 100e in a second direction (horizontal direction) intersecting the first direction. Here, in the case of the patch antenna used in this embodiment, the first direction is the terahertz wave resonance direction (resonant electric field propagation direction, electric field direction, or E direction), and the second direction is a direction orthogonal to the first direction (magnetic field direction or H direction). This invention is applicable not only to antennas radiating horizontally polarized waves or vertically polarized waves, but also to antennas radiating circularly polarized waves.

[0076] When focusing on antenna 100e, the configuration will be described as follows. Antennas 100d, 100e, and 100f are arranged in this order in a first direction (vertical direction). Antennas 100h, 100e, and 100b are arranged in this order in a second direction (horizontal direction) intersecting the first direction. Antennas 100e and 100f are coupled via a coupling line 109ef extending in the first direction, and antennas 100e and 100d are coupled via a coupling line 109de extending in the first direction. Antennas 100e and 100b are coupled via a coupling line 1091eb extending in the second direction, and antennas 100e and 100h are coupled via a coupling line 1091he extending in the second direction.

[0077] Here, we assume the first antenna is antenna 100e, the second antenna is antenna 100f, the third antenna is antenna 100d, the fourth antenna is antenna 100h, and the fifth antenna is antenna 100b. When the first direction is assumed to be the X direction and the second direction to be the Y direction, the configuration will be described as follows: The second, first, and third antennas are arranged in this order in the first direction. The fourth, first, and fifth antennas are arranged in this order in the second direction. The second conductor layer of the second antenna is connected to the second conductor layer of the first antenna via a first coupling line extending in the first direction, and the second conductor layer of the first antenna is connected to the second conductor layer of the third antenna via a second coupling line extending in the first direction. The second conductor layer of the fourth antenna is connected to the second conductor layer of the first antenna via a third coupling line extending in the second direction, and the second conductor layer of the first antenna is connected to the second conductor layer of the fifth antenna via a fourth coupling line extending in the second direction. Here, the first coupling line is coupling layer 109ef, and the second coupling line is coupling line 109de. The third coupling line is coupling line 1091he or coupling line 1092he, and the fourth coupling line is coupling line 1091eb or coupling line 1092eb.

[0078] like Figure 4 As shown, element 10 also includes coupling lines 1091he, 1092he, 1091eb, and 1092eb extending in a second direction (horizontal direction) intersecting the first direction (vertical direction). The coupling lines 1091he and 1091eb extending in the second direction are connected to coupling lines 109hi, 109ef, and 109bc extending in the first direction. The coupling lines 1092he and 1092eb extending in the second direction are connected to coupling lines 109gh, 109de, and 109ab extending in the first direction. Through this connection, multiple antennas 100 are coupled. Furthermore, through this connection, the antenna gain is increased. When the coupling lines are connected to each other, the coupling lines can be constructed from conductors in which the coupling lines are continuously formed (i.e., a single conductor body).

[0079] The coupling lines are preferably connected as follows. The coupling lines preferably have a length such that the electrical length between adjacent RTDs of the antenna is an integer multiple of 2π. When, for example, the X direction is taken as the first direction, the coupling line 109de extending in the X direction has a length such that the electrical length between RTD 100e and RTD 100d is 2π. When the Y direction is taken as the second direction, the coupling line 1091eb or coupling line 1092eb extending in the Y direction has a length such that the electrical length between RTD 100e and RTD 100b is 4π. Here, the electrical length is a wiring length that takes into account the propagation speed of the radio frequency wave propagating in the coupling line. Phase injection-locking can be easily performed from RTDs 101a to 101i of the antenna. The error in the length range is ±1 / 4π.

[0080] The coupling will be described. Figure 5A and 5B This is a schematic diagram illustrating element 10 according to this embodiment. Figure 5A and 5B It is a diagram that schematically illustrates the relationship between the antenna and the coupling line. Figure 5C This is a graph showing the correlation between the number of antennas and the radiation angle of electromagnetic waves.

[0081] Figure 5A The element 10 in which the antenna is coupled in the X and Y directions is shown. Figure 5B The configuration of element 10', in which the antenna is coupled only in the X direction, is shown. Here, "+" and "-" in the figure indicate the antinodes and polarities of the resonant electric field residing in the antenna array at a frequency of f THz, while "×" indicates the nodes of the resonant electric field. Element 10' does not couple the central antenna 100e to the two adjacent antennas (i.e., antennas 100h and 100b) in the Y direction via coupling lines, therefore the synchronization between the antennas in the Y direction is insufficient. Since antenna 100e of element 10 is connected to the adjacent antennas 100h and 100b in the Y direction via coupling lines, the antennas are fully synchronized in the Y direction. Therefore, the antenna gain is increased.

[0082] Furthermore, to satisfy the phase matching condition between antennas, the coupling lines in the X direction and the coupling lines in the Y direction are connected at a position where the axis of symmetry between adjacent antennas in the X direction is shifted in the X direction. In other words, the coupling lines in the X direction and the coupling lines in the Y direction are connected at a position where the center between adjacent antennas in the X direction is shifted in the X direction. For example, for antennas 100e and 100d adjacent in the X direction, the construction will be described as follows. When antennas 100e and 100d are linearly symmetrical with respect to a line segment extending in the Y direction, the point where this line segment intersects the X direction is taken as the point of symmetry. The coupling line 109de in the X direction and the coupling line 1092he in the Y direction are connected at a position shifted in the X direction from the point of symmetry. The coupling line 109de in the X direction and the coupling line 1092eb in the Y direction are connected at a position shifted in the X direction from the point of symmetry. The shift amount is, for example, 30µm. Figure 1A In this example, assume that the distance between the two antennas 100 in the X direction is a length LX1, and the distance between the two antennas 100 in the Y direction is a length LY1. Here, the connection between coupling lines 109ab and 1092eb is shifted from the center of length LX1 towards antenna 100a. This shift is also referred to as offset.

[0083] More preferably, the coupling lines in the X and Y directions are connected at locations outside the nodes of the resonant electric field residing in the coupling lines at terahertz wave frequencies. In other words, the coupling lines in the X and Y directions are preferably connected at locations shifted from the electrical symmetry center of the terahertz wave frequency f THz between adjacent antennas in the X direction. This is because when the two coupling lines are connected at locations outside the nodes of the resonant electric field residing in the coupling lines at terahertz wave frequencies, the phase matching conditions between vertically arranged antennas contradict those between horizontally arranged antennas. Therefore, destructive interference between outputs may occur. Directivity may change.

[0084] Figure 5C This is a graph showing the correlation between the number of antennas and the radiation angle. The solid and dashed lines on the graph represent calculated values ​​(calculated using HFSS generated by ANSYS), and the plotted points represent measured data for 2x2, 4x4, 5x5, and 6x6 arrays. It appears that for element 10', where the antennas are coupled only in the vertical direction, synchronization in the horizontal direction is insufficient in 3x3 or larger antenna arrays. The effect of improving directivity then seems to saturate. For the configuration of element 10, where the antennas are coupled in two directions (i.e., vertical and horizontal), improved directivity is confirmed on both the calculated and measured sides, and the radiation angle sharpens in both the vertical and horizontal directions as the number of antennas increases. This indicates that, due to the effect of the coupling lines connected in the horizontal direction, synchronization between antennas is sufficiently achieved in both the vertical and horizontal directions even in 3x3 or larger antenna arrays with an increased number of antennas, such as antenna 100e. In other words, the phase-matching condition is met between the antennas. Therefore, for the element according to this embodiment, even an antenna surrounded by adjacent antennas in an M×N array (M and N are natural numbers), enhanced coupling and phase matching are achieved at least in the vertical direction and in both the vertical and horizontal directions. Therefore, with Figure 5B Compared to the case shown where only element 10' synchronizes the antenna in the vertical direction, Figure 5A The element 10 shown is intended to enhance the strength of the antenna output. Improved directivity is expected.

[0085] The construction of deploying coupling lines between antennas in the vertical and horizontal directions is a suitable construction to minimize the number of coupling lines in order to reduce the loss in terahertz waves due to coupling; however, the construction is not limited to this.

[0086] The detailed construction of the antenna will be described below. Figure 3A and 3BAs shown, antenna 100a has a first conductor layer 106, a second conductor layer 103a, and a dielectric layer 104. The dielectric layer 104 is located between the two conductor layers (wiring layers) (i.e., the first conductor layer 106 and the second conductor layer 103a). The above-described configuration of antenna 100a is referred to as a microstrip antenna using microstrip lines of finite length, etc. In this embodiment, an example of a patch antenna using a microstrip resonator will be described.

[0087] like Figure 3A and 3B As shown, the second conductor layer 103a is a patch conductor of the antenna 100a, deployed opposite the first conductor layer 106 across the dielectric layer 104 (semiconductor layer 115a). The second conductor layer 103a is electrically connected to the semiconductor layer 115a. The antenna 100a is configured to operate as a resonator with a width of λTHz / 2 in the A-A' direction (resonance direction) of the second conductor layer 103a. The first conductor layer 106 is an electrically grounded conductor. λTHz is the effective wavelength of the terahertz wave in the dielectric layer 104 resonating in the antenna 100a. λTHz is defined as the wavelength of the terahertz wave in vacuum being λ0 and the effective dielectric constant of the dielectric layer 104 being εr.

[0088] =λ0 × εr-1 / 2.

[0089] like Figure 3A and 3B As shown, antenna 100a has a semiconductor structure. The semiconductor structure is, for example, a mesa structure. The semiconductor structure includes semiconductor layer 115a and semiconductor layer 101a. Furthermore, the semiconductor structure has a third electrode 116a as an ohmic electrode. Semiconductor layer 115a is located within antenna 100a and is constructed to oscillate or detect terahertz waves. Figure 1A As shown, only the semiconductor layer 101a is shown in the antenna 100a; however, the semiconductor layer 115a is also deployed between the semiconductor layer 101a and the second conductor layer 103a.

[0090] In the following description, semiconductor layer 101a will be described. Semiconductor layer 101a is composed of a nonlinear semiconductor layer having electromagnetic wave gain or terahertz wave gain. A typical semiconductor layer having electromagnetic wave gain in the terahertz wave band is a resonant tunneling diode (RTD), and is also called an active layer. In this embodiment, an example using an RTD as semiconductor layer 101a will be described. In the following description, semiconductor layer 101a may also be referred to as RTD 101a.

[0091] RTD 101a features a multi-quantum-well structure, providing a resonant tunneling structure layer comprising multiple tunneling barrier layers, quantum well layers between these tunneling barrier layers, and terahertz waves generated by carrier migration between subbands. RTD 101a exhibits electromagnetic wave gain within the frequency range of terahertz waves based on photon-assisted tunneling within the differential negative resistance range of the current-voltage characteristics, and self-oscillates within the differential negative resistance range.

[0092] Antenna 100a is an active antenna in which RTD 101a, semiconductor layer 115a, and patch antenna are integrated. The frequency f THz of the terahertz wave oscillating solely from antenna 100a is determined by the resonant frequencies of all parallel resonant circuits obtained by combining the reactance of the patch antenna with that of semiconductor layer 115a. Specifically, according to the equivalent circuit of the oscillator described in NPL 1, the frequency satisfying the amplitude condition of expression (1) and the phase condition of expression (2) is determined as the oscillation frequency f THz of the resonant circuit used to combine the RTD with the antenna admittance (YRTD and Yaa).

[0093] Re[YRTD]+Re[Yaa]≤0(1)

[0094] Im[YRTD]+Im[Yaa]=0(2)

[0095] Here, YRTD is the admittance of semiconductor layer 115a, Re represents the real part, and Im represents the imaginary part. Since semiconductor layer 115a includes RTD 101a as a negative resistive element, Re[YRTD] has a negative value. Yaa represents the admittance of the overall structure of patch antenna 100a as viewed from semiconductor layer 115a.

[0096] A quantum cascade laser (QCL) with a multilayer semiconductor structure of hundreds to thousands of layers can be used as semiconductor layer 101a. In this case, semiconductor layer 115a is a semiconductor layer including the QCL structure. Alternatively, negative resistance elements such as Gunn diodes and IMPATT diodes, commonly used in the millimeter-wave band, can be used as semiconductor layer 101a. Radio frequency elements, such as transistors whose one end is terminated, can be used as semiconductor layer 101a. Heterojunction bipolar transistors (HBTs), compound semiconductor layer FETs, high electron mobility transistors (HEMTs), etc., can be suitable as transistors. Differential negative resistance, such as Josephson devices using superconducting layers, can be used as semiconductor layer 101a.

[0097] The dielectric layer 104 consists of two layers: a first dielectric layer 1041 and a second dielectric layer 1042. Microstrip resonators, such as patch antennas, have a thick dielectric layer 104, thus reducing conductor losses and improving radiation efficiency. It is desirable that the dielectric layer 104 allow for the formation of a thick film (typically 3 μm or greater) to provide low loss and low dielectric constant in the terahertz band, and to have good micromachinability (planarization and etching). Here, radiation efficiency increases with increasing dielectric layer 104 thickness; however, if the dielectric layer 104 is too thick, multimode resonance may occur. Therefore, the thickness of the dielectric layer 104 is preferably designed to be less than or equal to 1 / 10 of the oscillation wavelength, which serves as an upper limit. On the other hand, for high-frequency, high-power oscillators, miniaturization and high current density of the diode are required; therefore, it is desirable that the dielectric layer 104 act as an insulating structure for the diode to suppress leakage current and take measures to prevent migration. In this embodiment, in order to achieve the above two objectives, the first dielectric layer 1041 and the second dielectric layer 1042 are respectively made of two different materials.

[0098] As a specific example of the material for the first dielectric layer 1041, organic dielectric materials such as benzocyclobutene (BCB, manufactured by Dow Chemical Company, εr1 = 2), polytetrafluoroethylene, and polyimide are suitably used. Here, εr1 is the dielectric constant of the first dielectric layer 1041. For the first dielectric layer 1041, inorganic dielectric materials with low dielectric constants that can form relatively thick films can be used, such as TEOS oxide films and spin-coated glass.

[0099] Insulation properties (the ability to function as an electrical insulator and a high-resistance electrode, and to not conduct current under DC voltage), barrier properties (the ability to prevent the diffusion of metallic materials used for electrodes), and processability (the ability to be processed with submicron precision) are desirable for the second dielectric layer 1042. As specific examples of materials that satisfy these properties, inorganic electrical insulating materials such as silicon oxide (εr² = 4), silicon nitride (εr² = 7), aluminum oxide, and aluminum nitride are suitable. εr² is the dielectric constant of the second dielectric layer 1042.

[0100] Here, when the dielectric layer 104 has a two-layer structure as in this embodiment, the dielectric constant εr of the dielectric layer 104 is the effective dielectric constant determined by the thickness and dielectric constant εr1 of the first dielectric layer 1041 and the thickness and dielectric constant εr2 of the second dielectric layer 1042. From the perspective of impedance matching between the antenna and space, the smaller the difference in dielectric constant between the antenna and air, the better. Therefore, a material different from the material of the second dielectric layer 1042 and having a lower dielectric constant (εr1 < εr2) should be used as the first dielectric layer 1041. In element 10, the dielectric layer 104 does not need to have a two-layer structure and can have a structure consisting of only one layer selected from the above materials.

[0101] A semiconductor layer 115a is disposed on a first conductor layer 106 formed on a substrate 113. The semiconductor layer 115a and the first conductor layer 106 are electrically connected to each other. To reduce ohmic losses, the semiconductor layer 115a and the first conductor layer 106 are preferably connected with low resistance. An electrode 116a is disposed on the side of the semiconductor layer 115a opposite to the side where the first conductor layer 106 is disposed. The electrode 116a and the semiconductor layer 115a are electrically connected to each other. The semiconductor layer 115a and the electrode 116a are embedded in and covered by a second dielectric layer 1042.

[0102] As long as electrode 116a is an ohmic conductor connected to semiconductor layer 115a, electrode 116a is suitable for reducing ohmic losses and RC delay due to series resistance. When electrode 116a is used as an ohmic electrode, materials such as Ti / Pd / Au, Ti / Pt / Au, AuGe / Ni / Au, TiW, Mo, and ErAs are suitable. When the region of semiconductor layer 115a in contact with electrode 116a is a heavily doped semiconductor, the contact resistance is further reduced, which is suitable for high power and high frequency applications. The absolute value of the negative resistance, representing the gain of RTD 101a used in the terahertz wave band, is approximately on the order of 1Ω to 100Ω, so electromagnetic wave losses are appropriately suppressed to less than or equal to 1%. Therefore, as a target, the contact resistance of the ohmic electrode should be suppressed to less than or equal to 1Ω. To operate in the terahertz frequency band, the width of the semiconductor layer 115a (which is almost equal to that of the electrode 116a) is typically between approximately 0.1 μm and approximately 5 μm. For this purpose, by setting the resistivity to less than or equal to 10 Ω·μm², the contact resistance is appropriately suppressed to the range of 0.001 Ω to a few Ω.

[0103] It is conceivable to use a non-ohmic connection, but rather a Schottky connection, to the metal of electrode 116a. In this case, the contact interface between electrode 116a and semiconductor layer 115a has rectifying characteristics, and antenna 100a has a suitable configuration as a terahertz wave detector. In the following, in this embodiment, a configuration using an ohmic electrode as electrode 116a will be described.

[0104] like Figure 3A As shown, in the antenna 100a deployed on the upper and lower sides of RTD 101a, the substrate 113, the first conductor layer 106, the semiconductor layer 115a, the electrode 116a, the conductor 117a, and the second conductor layer 103a are laminated in this order.

[0105] Conductor 117a is formed in dielectric layer 104, and the second conductor layer 103a and electrode 116a are electrically connected to each other via conductor 117a. Here, if the width of conductor 117a is too large, the resonant characteristics of the patch antenna 100a deteriorate, and the radiation efficiency decreases due to increased parasitic capacitance. Therefore, the width of conductor 117a is preferably set to a degree that does not interfere with the resonant electric field, and is generally suitably less than or equal to 1 / 10 of the effective wavelength λ of the terahertz wave residing in antenna 100a with an oscillation frequency of f THz. The width of conductor 117a can be small enough that the series resistance does not increase, and as a target, it can be reduced to approximately twice the skin depth. When considering reducing the width of conductor 117a to a level where the series resistance does not exceed 1 Ω, as a target, the width of conductor 117a is generally in the range of greater than or equal to 0.1 μm and less than or equal to 20 μm.

[0106] exist Figure 1A In the circuit, the second conductor layer 103a is electrically connected to line 108a1 via conductor 107a1 and to line 108a2 via conductor 107a2. Lines 108a1 and 108a2 are extensions electrically connected to the bias circuit 120 via a bias line 111 formed within the chip as a common wiring. Line 108 extends from each antenna. The bias circuit 120 is a power supply for supplying a bias signal to the RTD 101a of antenna 100a. Therefore, when the bias line 111 is connected to lines 108 extending from adjacent antennas respectively, the bias signal is supplied to the semiconductor layer 115 of the antenna. Since sufficient wiring width is ensured by the common bias line 111, the operating voltage variation between antennas due to changes in wiring resistance is reduced, thus ensuring stable synchronization even when the number of antennas increases. Furthermore, the structure of the area around each antenna can be made symmetrical, so the radiation pattern is not distorted.

[0107] Conductor 107a1 is a connection portion for electrically and mechanically connecting wire 108a1 to the second conductor layer 103a, and conductor 107a2 is a connection portion for electrically and mechanically connecting wire 108a2 to the second conductor layer 103a. Structures electrically interconnecting the upper and lower layers, such as conductors 117a and 107a1, 107a2, are referred to as vias. Each of the first conductor layer 106 and the second conductor layer 103a serves not only as a component of the patch antenna assembly but also as an electrode for injecting current into the RTD 101a when connected to these vias. Conductors 117a and 107a1, 107a2, which serve as vias, have a resistivity less than or equal to 1 × 10⁻⁶. -6 Materials with an Ω·m content are preferred. Specifically, metals or metal compounds, such as Ag, Au, Cu, W, Ni, Cr, Ti, Al, AuIn alloys, and TiN, are suitable as materials.

[0108] The width of each of conductors 107a1 and 107a2 is smaller than the width of the second conductor layer 103a. Here, the width is the width in the electromagnetic wave resonance direction (=A-A' direction) of the antenna 100a. The width of the portion of line 108a1 (line 108a2) connecting to conductor 107a1 (conductor 107a2) (connection portion) is smaller (narrower) than the width of the second conductor layer 103a (antenna 100a). These widths are suitably less than or equal to 1 / 10 (less than λ / 10) of the effective wavelength λ of the terahertz wave residing in the antenna 100a with an oscillation frequency of f THz. This is because it is preferable to deploy conductors 107a1 and 107a2 and lines 108a1 and 108a2 at a dimension such that conductors 107a1 and 107a2 and lines 108a1 and 108a2 do not interfere with the resonant electric field in the antenna 100a, in order to improve radiation efficiency.

[0109] The conductors 107a1 and 107a2 are preferably positioned at nodes of the electric field residing in the terahertz wave with an f THz oscillation frequency in the antenna 100a. In this case, conductors 107a1 and 107a2 and lines 108a1 and 108a2 are components with impedances in the frequency band near the f THz oscillation frequency that are significantly higher than the absolute value of the differential negative resistance of the RTD 101a. In other words, each of lines 108a1 and 108a2 is connected to an antenna other than the antenna 100a to have high impedance when viewed from the RTD at the f THz oscillation frequency. In this configuration, the other antenna and antenna 100a are isolated (separated) via the path of bias line 111 at the f THz frequency. Therefore, the current induced in each antenna with the f THz oscillation frequency does not affect adjacent antennas through bias line 111 and bias circuit 120. Furthermore, interference between the electric field residing in antenna 100a and these power supply components, which has an oscillation frequency of f THz, is suppressed. The other antennas 100b to 100i in element 10 are similar to antenna 100a.

[0110] Bias line 111 is a shared bias wiring line (wiring layer) for antennas 100a to 100i. Antennas 100a to 100i are connected to bias line 111 via lines 108a1, 108a2 to lines 108i1, 108i2, respectively. In bias line 111, the wiring in the A-A' direction (resonance direction)... Figure 3A The wiring is shown as lines 111x1 to 111x4, and the wiring in the B-B' direction is... Figure 3B The lines are shown as 111y1 to 111y4. In the description, the entire bias common wiring line of component 10 is referred to as bias line 111.

[0111] exist Figure 2 In this circuit, bias circuit 120 is deployed outside the chip to supply a bias signal to the RTDs 101a to 101i. Bias circuit 120 includes a shunt resistor 121, wiring line 122, power supply 123 connected in parallel with each of the RTDs 101a to 101i, and a capacitor 124 connected in parallel with the shunt resistor 121.

[0112] Wiring line 122 definitely has a parasitic inductance component, therefore wiring line 122 in Figure 2 The circuit is shown as an inductor. Power supply 123 supplies the required current to drive each of the RTDs 101a to 101i and adjusts the bias voltage applied to each of the RTDs 101a to 101i. The bias voltage is typically selected from the range of the differential negative resistance of the RTDs 101a to 101i. Bias circuit 120 is connected to bias line 111, which is an in-chip wiring. In the case of antenna 100a, the bias voltage from bias circuit 120 is supplied to RTD 101a in antenna 100a through lines 108a1 and 108a2. The other antennas 100b to 100i are similar to antenna 100a.

[0113] Shunt resistor 121 and capacitor 124 are used to suppress parasitic oscillations at relatively low frequencies (typically from DC to 10 GHz) due to bias circuit 120. The value of shunt resistor 121 is chosen to be equal to or slightly less than the absolute value of the differential negative resistance of the combined resistance of the parallel-connected RTDs 101a to 101i. Capacitor 124 and shunt resistor 121 are also configured such that the impedance of the components is equal to or less than the absolute value of the combined differential negative resistance of the parallel-connected RTDs 101a to 101i. In other words, using these shunt structures, bias circuit 120 is configured with an impedance lower than the absolute value of the combined negative resistance corresponding to the gain in the DC to 10 GHz frequency band. Generally, capacitor 124 is preferably larger within the aforementioned range, and in this example embodiment, capacitor 124 is approximately tens of picofarads. Capacitor 124 is a decoupling capacitor and can, for example, be a metal-insulator-metal (MIM) structure in which antenna 100a and a substrate are integrated.

[0114] Element 10 is an antenna array with nine antennas 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h, and 100i deployed in a 3x3 matrix. Each of antennas 100a to 100i oscillates only a terahertz wave with a frequency of f THz. Adjacent antennas are coupled to each other via coupling line 109 and are mutually injected-locked (synchronized) at the oscillation frequency of the terahertz wave at f THz.

[0115] Here, mutual injection-locking refers to the synchronization of multiple self-excited oscillators due to their interaction. For example, antennas 100a and 100b are coupled to each other via coupling line 109ab, and antennas 100a and 100d are coupled to each other via coupling line 109ad. This also applies to other adjacent antennas. The term "coupled to each other" refers to the phenomenon where the current induced in one antenna acts on another adjacent antenna to change their mutual transmission and reception characteristics. By synchronizing the mutually coupled antennas in phase or out of phase, the mutual injection-locking phenomenon causes an enhancement or disruption of the electromagnetic field between the antennas. Therefore, the increase or decrease of antenna gain can be adjusted. In the description, when referring to the entire coupling line of the antenna of coupling element 10, the coupling line is called coupling line 109. The letter corresponding to each antenna is used to indicate the coupling line of two adjacent antennas in the coupled antenna and is a component of coupling line 109. For example, the coupling line that couples antennas 100a and 100b is called coupling line 109ab.

[0116] The oscillation condition of element 10 is determined by the mutual injection-lock condition in the construction in which two or more individual RTD oscillators described in J. Appl. Phys., Vol. 103, 124514 (2008) (NPL 2) are coupled. Specifically, consider the oscillation condition of an antenna array in which antennas 100a and 100b are coupled via coupling line 109ab. At this time, two oscillation modes appear, namely, mutual injection-lock and anti-mutual injection-lock. The oscillation condition of the mutual injection-lock oscillation mode (even mode) is expressed by mathematical expressions (4) and (5), while the oscillation condition of the anti-mutual injection-lock oscillation mode (odd mode) is expressed by mathematical expressions (6) and (7).

[0117] In-phase (even mode): Frequency f = feven

[0118] Yeven=Yaa+Yab+YRTD

[0119] Re(Yeven)≤0(4)

[0120] Im(Yeven)=0(5)

[0121] Inverted (odd mode): Frequency f = fodd

[0122] Yodd = Yaa + Yab + YRTD

[0123] Re(Yodd)≤0(6)

[0124] Im(Yodd)=0(7)

[0125] Here, Yab is the mutual admittance between antennas 100a and 100b. Yab is proportional to the coupling constant indicating the coupling strength between the antennas, and ideally, preferably, Yab has a large real part and a zero imaginary part. In element 10 according to this embodiment, the antennas are coupled under the condition that the antennas are subject to mutual injection-lock and the oscillation frequency f THz ≈ feven. Similarly, for other antennas, any two adjacent antennas are coupled in the coupling line 109 to satisfy the above-described mutual injection-lock condition.

[0126] The coupling line 109 is a microstrip line sandwiched between the third conductor layer 110 and the first conductor layer 106 by the dielectric layer 104. For example, as... Figure 3A As shown, coupling line 109ab has a dielectric layer 104 sandwiched between the third conductor layer 110ab and the first conductor layer 106. Similarly, coupling line 109bc is formed such that the dielectric layer 104 is sandwiched between the third conductor layer 110bc and the first conductor layer 106, coupling line 109ad is formed such that the dielectric layer 104 is sandwiched between the third conductor layer 110ad and the first conductor layer 106, and coupling line 109cf is formed such that the dielectric layer 104 is sandwiched between the third conductor layer 110cf and the first conductor layer 106.

[0127] exist Figure 4 In this configuration, any two adjacent antennas of element 10 are coupled via DC coupling. The third conductor layer 110ab, which serves as the upper conductor layer of the coupling line 109ab connecting antenna 100a to antenna 100b, is directly connected to the second conductor layers 103a and 103b. (Example...) Figure 3A , 3B As shown in Figure 4, in element 10, the third conductor layer 110ab and the second conductor layers 103a and 103b are formed in the same layer. Similarly, the third conductor layer 110ae, which serves as the upper conductor layer of the coupling line 109ae that couples antenna 100a to antenna 100e, is directly connected to the second conductor layers 103a and 103e. The third conductor layer 110ae is formed in the same layer as the second conductor layers 103a and 103e.

[0128] With this structure, each of antennas 100b and 100e is coupled to antenna 100a and operates synchronously with each other at the frequency f THz of the oscillating terahertz wave. Antenna arrays using this DC-coupled synchronization can synchronize adjacent antennas with strong coupling; therefore, the array is easy to pull-in synchronization and is less susceptible to frequency and phase variations of each antenna.

[0129] In component 10, coupling line 109 and bias line 111 are deployed in different layers. For example, as Figure 3AAs shown, the third conductor layer 110ab, which serves as a component of the coupling line 109ab coupling antenna 100a to antenna 100b, and the fourth conductor layer 111x2, which serves as a component of the bias line 111, are deployed in different layers. Similarly, the third conductor layer 110ad, which serves as a component of the coupling line 109ad coupling antenna 100a to antenna 100d, and the fourth conductor layer 111x1, which constitutes the bias line 111, are deployed in different layers. In other words, the wiring layer having a portion of the coupling line 109 extending in the in-plane direction (perpendicular to the lamination direction) of the substrate 113 and the wiring layer having a portion of the bias line 111 extending in the in-plane direction of the substrate 113 are deployed in different layers. Here, the wiring layer having the portion of the coupling line 109 extending in the in-plane direction is the third conductor layer 110 and the first conductor layer 106. On the other hand, the wiring layer having the portion of the bias line 111 extending in the in-plane direction is the fourth conductor layer 111. In this embodiment, all third conductor layers 110 and first conductor layers 106 in all antennas are deployed in a different layer than any of the fourth conductor layers 111.

[0130] In this way, the coupling line 109 for transmitting high frequencies (f THz) and the bias line 111 for transmitting low frequencies (DC to tens of GHz) are deployed in different layers. This allows for freedom in setting the width, length, and layout of the transmission lines in each layer, such as their installation.

[0131] In component 10, substrate 113, first conductor layer 106, and second conductor layer 103a are laminated in this order, starting from substrate 113. At least one of coupling line 109 and bias line 111 is disposed in the layer between first conductor layer 106 and second conductor layer 103a. For example, as Figure 3A As shown, the fourth conductor layers 111x2 and 111x1 are deployed in the layer between the first conductor layer 106 and the second conductor layer 103.

[0132] In addition, such as Figure 1A As shown, when viewed from above (in a plan view), coupling line 109 and bias line 111 intersect each other. For example, in a plan view, third conductor layer 110ab intersects with fourth conductor layer 111x2, and third conductor layer 110ad intersects with fourth conductor layer 111y3. Figure 3A and 3B As shown, the intersecting conductor layers are located at different levels.

[0133] In this way, by laying the wiring so that the coupling line 109 and the bias line 111 intersect each other, a layout with further space-saving design is achieved. Therefore, using this configuration, the number of antennas deployed in an antenna array with an m x n matrix (m ≥ 2, n ≥ 2) increases. According to this embodiment, even when the number of antennas increases, physical interference between the coupling line (coupling line 109) used for synchronization between antennas and the power supply line (bias line 111) used to supply bias voltage to each RTD 101 is suppressed. Therefore, in element 10, the upper limit on the number of antennas arranged is relaxed, and thus, a significant improvement in directivity and frontal strength due to the increased number of antennas is expected.

[0134] A space-saving layout configuration is achieved by deploying at least one of the coupling line 109 and the bias line 111 in a layer between two conductor layers of the antenna component. Specifically, the coupling line 109 and / or the bias line 111 are embedded in a redundant region of the dielectric layer 104, which is the component of antennas 100a to 100i, excluding the antennas. With this configuration, multiple transmission lines can be deployed in a relatively small space between adjacent antennas spaced at approximately wavelengths, thus being fully compatible with the increase in the number of lines caused by an increase in the number of antennas.

[0135] Since the resistance increases due to the skin effect in the terahertz band, the conductor loss generated by high-frequency transmission between antennas cannot be ignored. The conductor loss per unit length (dB / mm) increases with increasing current density between conductor layers. In the case of microstrip lines, the conductor loss per unit length (dB / mm) is inversely proportional to the square of the dielectric thickness. Therefore, to improve the radiation efficiency of the antenna array, it is appropriate to reduce conductor loss by increasing not only the thickness of the antenna but also the thickness of the dielectric component serving as the coupling line 109. In contrast, in element 10 according to this embodiment, the bias line 111 is deployed on the side of the first conductor layer 106 in the first dielectric layer 1041, and the third conductor layer 110 through which the radio frequency at a frequency of f THz is transmitted is deployed in an upper layer above the dielectric layer 104. With this configuration, the reduction in radiation efficiency of the antenna array caused by conductor loss in the terahertz band is suppressed. In this configuration, in antenna 100a, substrate 113, first conductor layer 106, fourth conductor layers 111x1, 111x2, second conductor layer 103a, and third conductor layers 110ad, 110ab are laminated sequentially from the substrate 113 side. This also applies to the relationship between coupling line 109 and bias line 111 that couple other antennas.

[0136] From the viewpoint of conductor loss, the thickness of the dielectric material of the component serving as coupling line 109 is preferably greater than or equal to 1 μm, and more preferably, when the dielectric thickness is set to be greater than or equal to 2 μm, the loss due to conductor loss in the terahertz band is suppressed to approximately 20%. Similarly, from the viewpoint of conductor loss, the distance in the thickness direction between the third conductor layer 110 and the first conductor layer 106, which serve as the component of coupling line 109, is preferably wider as much as possible. The distance in the thickness direction between the third conductor layer 110, which serves as the component of coupling line 109, and the fourth conductor layer 111, which serves as the component of bias line 111, is preferably wider as much as possible. For bias line 111, when the dielectric material is set to be less than or equal to 2 μm, preferably less than or equal to 1 μm, bias line 111 can be used as a low-impedance line up to the gigahertz band. Even when the dielectric is set to be thick, i.e., greater than or equal to 2 μm, the bias line 111 can be used as a low impedance line by connecting the shunt assembly to the bias line, as in the case of element 30.

[0137] In element 10 according to this embodiment, adjacent antennas are powered via a common bias line 111 deployed between the antennas. For example, as Figure 3B As shown, antenna 100a is connected to bias line 111y3 via conductor 107a2 and line 108a2, and antenna 100d is connected to bias line 111y3 via conductor 107d1 and line 108d1. Similarly, since antennas 100a and 100b are adjacent to each other, both antennas are connected to a common bias line 111x2 deployed between the antennas and supplied with bias signals. This also applies to the bias lines 111 of the other antennas 100b to 100i. In this way, when a common bias line 111, which is a wiring in the chip, is used between two adjacent antennas, the antennas are allowed to be driven by the same channel, thus simplifying the driving mode. Since the number of wiring lines is reduced, and therefore the thickness of a single wiring line can be increased, the increase in wiring resistance due to the increase in the number of antennas and the difference in operating points between two adjacent antennas can be suppressed accordingly. Thus, the frequency difference and phase difference between antennas caused by the increase in the number of antennas are suppressed, making it easier to obtain the synchronization effect of the array.

[0138] The shared bias line 111 is not an essential component. For example, multiple bias lines 111 can be prepared for each antenna to provide individual power by utilizing multilayering and miniaturization. In this case, the isolation between antennas through the bias line 111 is enhanced, thus reducing the risk of low-frequency parasitic oscillations. In element 10, lines 108a1, 108a2 to lines 108i1, 108i2 and bias line 111 preferably have an impedance lower than the negative resistance of RTDs 101a to 101i in the low-frequency band below the oscillation frequency f THz. More preferably, the impedance should be equal to or less than the absolute value of the combined differential negative resistance of the RTDs 101a to 101i connected in parallel. Therefore, multimode oscillations at low frequencies are suppressed.

[0139] As described above, according to this embodiment, by synchronizing the antenna array, oscillation or detection is performed with higher accuracy than in the prior art.

[0140] Reference Figure 1A and 2 The specific construction of the element 10 for oscillating terahertz waves according to the first embodiment is described. Element 10 is a semiconductor device capable of performing single-mode oscillation in a frequency band of 0.45 THz to 0.50 THz. The substrate 113 is an InP substrate. RTDs 101a to 101i are fabricated from a multi-quantum-well structure of a matched InGaAs / AlAs lattice on the substrate 113, and in this embodiment, an RTD with a double-barrier structure is used. This is also referred to as a semiconductor layer heterostructure of the RTD.

[0141] The current-voltage characteristics of each of RTDs 101a to 101i result in a peak current density of 9 mA / μm in the measured values. 2 Furthermore, the differential negative conductance per unit area is 10 mS / μm. 2 In antenna 100a, a mesa structure is formed, consisting of a semiconductor layer 115a including RTD 101a and a third electrode 116a serving as an ohmic electrode. In this embodiment, the mesa structure has a circular shape with a diameter of 2 μm. The differential negative resistance of RTD 101a is approximately -30 Ω per diode. In this case, the differential negative conductance (GRTD) of the semiconductor layer 115a including RTD 101a is estimated to be approximately 30 mS, and the diode capacitance (CRTD) of RTD 101a is estimated to be approximately 10 fF.

[0142] Antenna 100a is a patch antenna having a structure in which dielectric layer 104 is sandwiched between a second conductor layer 103a, which serves as a patch conductor, and a first conductor layer 106, which serves as a ground conductor. A semiconductor layer 115a, including RTD 101a, is integrated into antenna 100a. Antenna 100a is a square patch antenna, wherein one side of the second conductor layer 103a is 150 μm, and the resonator length (L) of the antenna is 150 μm.

[0143] For the second conductor layer 103a, which serves as a patch conductor, and the first conductor layer 106, which serves as a ground conductor, metal layers with low resistivity, primarily composed of Au thin films, are used. The second conductor layer 103a is composed of a metal containing Ti / Au (=5 / 300nm). A dielectric layer 104 is deployed in the layer between the second conductor layer 103a and the first conductor layer 106. The dielectric layer 104 consists of two layers (i.e., a first dielectric layer 1041 made of 5μm thick benzocyclobutene (BCB, produced by Dow Chemical Company, εr1=2) and a second dielectric layer 1042 made of 2μm thick SiO2 (plasma CVD, εr2=4).

[0144] The first conductor layer 106 consists of a Ti / Pd / Au layer (20 / 20 / 200nm) and an electron concentration of 1x10⁻⁶. 18 cm -3 It is composed of a semiconductor layer consisting of a larger n+-InGaAs layer (100nm), and the metal and semiconductor layers are connected to each other by a low-resistance ohmic contact.

[0145] Electrode 116a is an ohmic electrode composed of a Ti / Pd / Au layer (20 / 20 / 200nm). Electrode 116a is coupled with an electron concentration of 1x10⁻⁶. 18 cm -3 Or a higher n+-InGaAs layer (100nm) is formed in the semiconductor layer 115a to form a low-resistance ohmic contact connection.

[0146] Around RTD 101a, substrate 113, first conductor layer 106, semiconductor layer 115a, electrode 116a, conductor 117a made of Cu-containing conductor, and second conductor layer 103a are laminated and electrically connected in this order from the substrate 113 side. RTD 101a is positioned 40% (60 μm) off one side of the second conductor layer 103a in the resonant direction (A-A' direction) from the center of gravity of the second conductor layer 103a. Here, the input impedance when supplying radio frequency from the RTD to the patch antenna is determined according to the position of RTD 101a in the antenna 100a. The second conductor layer 103a is connected to line 108a1 deployed in the lower layer through conductor 107a1, which is a through-hole made of Cu, and is connected to line 108a2 deployed in the lower layer through conductor 107a2, which is a through-hole made of Cu.

[0147] Lines 108a1 and 108a2 are constructed from a Ti / Au (=5 / 300nm) metal layer laminated on the second dielectric layer 1042. Lines 108a1 and 108a2 are connected to the bias circuit 120 via a bias line 111, which serves as a common wiring trace formed within the chip. The bias line 111 is constructed from a Ti / Au (=5 / 300nm) metal layer laminated on the second dielectric layer 1042. The antenna 100a is designed to oscillate at a frequency of f THz = 0.5THz when biased to the negative resistance region of the RTD 101a.

[0148] Each of conductors 107a1 and 107a2 has a cylindrical structure with a diameter of 10 μm. Each of lines 108a1 and 108a2 is formed by a pattern of a metal layer containing Ti / Au (=5 / 300nm), wherein the width in the resonant direction (=A-A' direction) is 10 μm and the length is 75 μm. The end of each of conductors 107a1 and 107a2 in the B-B' direction is connected to a second conductor layer 103a at the center in the resonant direction (=A-A' direction). The connection position corresponds to a node of the electric field residing in antenna 100a with a terahertz wave of f THz.

[0149] Element 10 is an antenna array in which nine antennas 100a to 100i are deployed in a 3x3 matrix. Each antenna is designed to oscillate a terahertz wave with a frequency f THz individually, and the antennas are deployed at a spacing of 340 μm in both the A-A' and B-B' directions. Adjacent antennas are coupled to each other via coupling lines 109 comprising a third conductor layer 110 made of Ti / Au (=5 / 300nm). For example, antennas 100a and 100b are coupled to each other via coupling line 109ab. The center antenna 100e is connected to antenna 100f via coupling line 109ef extending in the first direction (vertical direction), and is connected to antenna 100d via coupling line 109ed extending in the first direction (vertical direction). Similarly, antenna 100e is connected to adjacent antennas 100h and 100b via coupling lines 1091he, 1092he, 1091eb, and 1092eb extending in the second direction (horizontal direction), respectively. Here, in the case of antennas 100e and 100d, the vertical coupling line 109de and the horizontal coupling lines 1092he and 1092eb are connected at a position shifted 30 μm from the vertical center of symmetry of antennas 100e and 100d in the A-A' direction. In other words, the vertical coupling line 109de and the horizontal coupling lines 1092he and 1092eb are connected at a position outside the center of the line segment connecting antennas 100e and 100d. The second conductor layer 103a and the second conductor layer 103b are directly connected via a third conductor layer 110ab formed in the same layer, with a width of 5 μm and a length of 190 μm. Antennas 100a and 100d are coupled to each other via coupling line 109ad. The second conductor layer 103a and the second conductor layer 103d are directly connected via a third conductor layer 110ad, which is 5 μm wide and 440 μm long and formed in the same layer. This also applies to the other antennas. Antennas 100a to 100i undergo mutual injection-locking and oscillate at an oscillation frequency of f THz = 0.5 THz in a phase-matched (in-phase) state.

[0150] The bias line 111, which is a common wiring line formed in the chip, is a bias wiring line shared by the antenna and is connected to the lines 108a1, 108a2 to 108i1, 108i2 respectively connected to the antennas 100a to 100i.

[0151] In component 10, similar to the relationship between the third conductor layer 110ab of coupling line 109ab and the fourth conductor layer 111x1 of bias line 111, coupling line 109 and bias line 111 are deployed in different layers. In component 10, substrate 113, first conductor layer 106, and second conductor layer 103a are laminated in this order starting from substrate 113. Similar to the third conductor layer 110ab and fourth conductor layer 111x1, bias line 111 is deployed in the layer between the first conductor layer 106 and the second conductor layer 103a. Coupling line 109 and bias line 111 intersect each other. This also applies to the relationship between coupling line 109 and bias line 111 coupling other antennas 100b to 100i. With this configuration, physical interference between the coupling line (coupling line 109) used for synchronization between antennas and the power supply line (bias line 111) used to supply bias voltage to each RTD 101 is reduced. Therefore, the upper limit of the number of antennas that can be deployed is increased, and the expected effect of increased antenna number is a significant improvement in directivity and frontal strength.

[0152] (Component manufacturing method)

[0153] Next, a method for manufacturing (preparation method) of element 10 according to this embodiment will be described.

[0154] (1) First, an InGaAs / AlAs semiconductor multilayer film structure comprising semiconductor layers 115a to 115i, each including RTDs 101a to 101i, is epitaxially grown on a substrate 113 made of InP. This is formed by molecular beam epitaxy (MBE), metal-organic vapor phase epitaxy (MOVPE), or the like.

[0155] (2) A Ti / Pd / Au layer (20 / 20 / 200 nm) is deposited on the semiconductor layers 115a to 115i by sputtering as a component of the electrodes 116a to 116i, which serve as ohmic electrodes.

[0156] (3) Electrodes 116a to 116i and semiconductor layers 115a to 115i are each formed into a circular mesa shape with a diameter of 2 μm to form a mesa structure. Here, photolithography and dry etching using inductively coupled plasma (ICP) are used to form the mesa shape.

[0157] (4) On the etched surface, after forming the first conductor layer 106 on the substrate 113 by a stripping method, silicon oxide with a thickness of 2 μm is deposited by plasma CVD to serve as the second dielectric layer 1042.

[0158] (5) A Ti / Au layer (=5 / 300nm) is formed on the second dielectric layer 1042 as the fourth conductor layer 111, which is a component of lines 108a1 to 108i2 and bias line 111. (6) A 5μm thick BCB is embedded and planarized as the first dielectric layer 1041 by spin coating and dry etching.

[0159] (7) By photolithography and dry etching, the BCB and silicon oxide at the portions forming conductors 117a to 117i and conductors 107a1 to 107i2 that will serve as vias are removed to form via holes (contact holes). At this time, when photolithography including grayscale exposure is used, the taper angle of the via holes used to form the first dielectric layer 1041, the second dielectric layer 1042 and the coupling line 109 is selectively controlled.

[0160] (8) Conductors 117a to 117i and conductors 107a1 to 107i2, which are through holes, are formed in the through holes by Cu-containing conductors. The through holes are buried with copper and planarized by sputtering, electroplating and chemical mechanical polishing to form conductors 117a to 117i and conductors 107a1 to 107i2.

[0161] (9) An electrode Ti / Au layer (=5 / 300nm) is deposited by sputtering, which will serve as the second conductor layer 103a to 103i and the third conductor layer 110 as a component of the coupling line 109 in the antenna.

[0162] (10) The second conductor layers 103a to 103i and the third conductor layer 110, which is a component of the coupling line 109, are patterned by using photolithography and dry etching with inductively coupled plasma (ICP).

[0163] (11) Finally, the shunt resistor 121 and the capacitor 124 are formed and connected to the wiring line 122 and the power supply 123 by wire bonding or the like, thereby completing component 10. The capacitor 124 is, for example, a metal-insulator-metal (MIM) capacitor.

[0164] Power is supplied to element 10 from bias circuit 120. When a bias voltage, which typically causes a differential negative resistance range, is applied to supply bias current, element 10 operates as an oscillator.

[0165] The element 10 according to this embodiment has a suitable antenna array. Therefore, it is possible to provide an antenna array that achieves at least one of improved antenna gain and improved directivity.

[0166] It is possible Figure 1B Each antenna 100 of the modified element 10 shown. Figure 1B It is shown Figure 1A A top schematic diagram showing a modification of the antenna 100a of element 10 shown. Figure 1B In the antenna 100a, there are at least two semiconductor layers, namely semiconductor layer 101a1 and semiconductor layer 101a2. Semiconductor layer 101a1 and semiconductor layer 101a2 each have a structure equivalent to that of semiconductor layer 101. This structure further improves the gain of the antenna.

[0167] Antenna 100a is a square patch antenna. Figure 1B In the diagram, the line segments connecting the centers of the two opposite sides of each patch antenna are represented by dashed lines. The intersection of these dashed lines is the center of the patch antenna. Each of conductors 107a1 and 107a2 is located at the center of both sides of the patch antenna, extending in the X direction. Semiconductor layers 101a1 and 101a2 are located within the dashed lines connecting the centers of the two sides of the patch antenna, extending in the Y direction. Semiconductor layers 101a1 and 101a2 are equidistant from the center of the patch antenna. With this configuration, the antenna operation becomes stable.

[0168] (Second Embodiment)

[0169] Figure 6A , 6B Figures 7A and 7B are schematic structural diagrams and schematic cross-sectional views of element 20 according to the second embodiment. Components and structures in element 20, except those described below, are similar to the components of the same name in element 10 according to the first embodiment, and therefore detailed descriptions are omitted. Figure 6A It is the same as the first embodiment Figure 4 The corresponding diagram, Figure 6B It is the same as the first embodiment Figure 5A The corresponding diagram will be provided, and redundant descriptions will not be repeated. Figure 6B It is used for illustration. Figure 6A A schematic diagram showing the positions of nodes and antinodes in the resonant electric field of the structure. Figure 7A and Figure 7B These are respectively the first embodiment Figure 3A and Figure 3B The corresponding view will be provided, and redundant descriptions will no longer be repeated.

[0170] Element 20 is an antenna array in which nine antennas 200a to 200i are deployed in a 3x3 matrix. Unlike the first embodiment, antenna 200a includes two semiconductor layers that have electromagnetic wave gain or nonlinearity for terahertz waves within an antenna. Specifically, as... Figure 7A As shown, antenna 200a includes a semiconductor layer 215a1 containing RTD 201a1 and a semiconductor layer 215a2 containing RTD 201a2.

[0171] exist Figure 7AIn this configuration, electrode 216a1 is disposed on the side of semiconductor layer 215a1 opposite to the side where the first conductor layer 206 is disposed, and electrode 216a2 is disposed on the side of semiconductor layer 215a2 opposite to the side where the first conductor layer 206 is disposed. Semiconductor layer 215a1 is disposed between the first conductor layer 206 and electrode 216a1, and semiconductor layer 215a2 is disposed between the first conductor layer 206 and electrode 216a2. Electrode 216a1 is electrically connected to semiconductor layer 215a1, and electrode 216a2 is electrically connected to semiconductor layer 215a2. A bias signal is supplied from bias circuit 120 to two RTDs 201a1 and 201a2 through conductor 217a1, which serves as a through-hole connecting electrode 216a1 and the second conductor layer 203a, and conductor 217a2, which serves as a through-hole connecting electrode 216a2 and the second conductor layer 203a.

[0172] like Figure 6A As shown, RTD 201a1 is deployed at a position 40% of the length of the second conductor layer 203a shifted from its center of gravity in the resonant direction (i.e., the A-A' direction) to one side of the second conductor layer 203a. On the other hand, RTD 201a2 is deployed at a position -40% of the length of the second conductor layer 203a shifted from its center of gravity in the resonant direction (i.e., the A-A' direction) to one side of the second conductor layer 203a. In other words, RTD 201a1 and RTD 201a2 are deployed at positions symmetrical about an axis symmetrical about a straight line (centerline) passing through the center of gravity of the second conductor layer 203a and perpendicular to the resonant and lamination directions. In this case, RTD 201a1 and RTD 201a2 undergo mutual injection-locking and oscillate in a state where their phases are reversed (out of phase). In this way, the configuration of the RTDs symmetrical in both the left-right and up-down directions of the antenna more easily provides the effect of increased directivity and frontal strength resulting from the increased number of antennas.

[0173] The coupling line 209 is formed by a microstrip line in which dielectric layers 204 and 218 are sandwiched between a first conductor layer 206 and a fifth conductor layer 210 laminated on the dielectric layer 218, with the dielectric layer 218 laminated on the dielectric layer 204. For example, as... Figure 7A As shown, the coupling line 209ab has a structure in which the dielectric layer 204 and the dielectric layer 218 are sandwiched between the fifth conductor layer 210ab and the first conductor layer 206.

[0174] Similarly, coupling line 209bc has a structure in which dielectric layer 204 and dielectric layer 218 are sandwiched between first conductor layer 206 and fifth conductor layer 210bc provided as upper conductor layer, and coupling line 209ad has a structure in which dielectric layer 204 and dielectric layer 218 are sandwiched between first conductor layer 206 and fifth conductor layer 210ad provided as upper conductor layer.

[0175] Element 20 is an antenna array having a configuration in which the antennas are coupled via AC coupling (capacitive coupling). For example, the fifth conductor layer 210ab, which is the upper conductor layer of the coupling line 209ab that couples antennas 200a and 200b, overlaps with the second conductor layers 203a and 203b by 5 μm in a plan view with the radiating end as the center. This also applies to the coupling between any two adjacent antennas of the other antennas 200b to 200i.

[0176] In the overlapping sections of the conductor layers, the second conductor layers 203a and 203b, the dielectric layer 218, and the fifth conductor layer 210ab are laminated in this sequence to form a metal-insulator-metal (MIM) capacitor structure. Here, the second conductor layer 203a and the second conductor layer 203b are open-circuited in DC. Because the coupling strength is low in the low-frequency range below f THz, isolation between components is ensured. On the other hand, in the frequency band of the oscillation frequency f THz, the coupling strength between antennas can be adjusted using capacitors. This structure significantly reduces the coupling between antennas, thus suppressing transmission loss between antennas, and as a result, the radiation efficiency of the antenna array is expected to improve.

[0177] Element 20 according to this embodiment is an example in which two coupling lines extending in the second direction (horizontal direction) are deployed between an antenna 200e deployed at the center and an antenna adjacent to antenna 200e in the second direction (horizontal direction). Specifically, coupling lines 2091he, 2092fi, 2092cf, and 2091eb extending in the second direction (horizontal direction) are deployed between antennas 200e and 200f and connected to coupling line 209ef extending in the first direction. Coupling lines 2092he, 2091dg, 2091ad, and 2092eb extending in the second direction (horizontal direction) are deployed between antennas 200e and 200d and connected to coupling line 209de extending in the first direction.

[0178] The coupling lines in element 20 are arranged in a stepped configuration between the rows of antennas 200i, 200f, and 200c and the rows of antennas 200h, 200e, and 200b. Between these rows, coupling lines 209bc, 209hi, and 209ef are deployed in the X direction. Furthermore, between these rows, coupling lines 2092fi, 2092cf, 2091he, and 2091eb are deployed in the Y direction. Coupling lines 2092fi and 2092cf connect coupling line 209bc and coupling line 209hi. Coupling lines 2092fi and 2092cf are connected at coupling line 209ef. Coupling lines 2091he and 2091eb connect coupling line 209bc and coupling line 209hi. Coupling lines 2091he and 2091eb are connected at coupling line 209ef. The coupling line can be made from a single electrical conductor. Antenna 200 and the coupling line are connected via AC coupling.

[0179] Couplers are further arranged in a stepped shape between the rows of antennas 200h, 200e, and 200b and the rows of antennas 200g, 200d, and 200a. Couplers 209gh, 209de, and 209ab are arranged in the X direction between these rows. Additionally, couplers 2092he, 2092eb, 2091dg, and 2091ad are arranged in the Y direction between these rows. Couplers 2092he and 2092eb are connected to couplers 209gh and 209ab. Couplers 2092he and 2092eb are connected at coupler 209de. Couplers 2091dg and 2091ad are connected to couplers 209gh and 209ad. Couplers 2091dg and 2091ad are connected at coupler 209de. The coupling line can be made from a single electrical conductor. Antenna 200 and the coupling line are connected via AC coupling.

[0180] Here, to satisfy the phase matching condition between the antennas, a coupling line extending in the second direction (horizontal direction) is connected to a coupling line in the first direction at a position shifted a predetermined distance from the symmetrical center between adjacent antennas in the first direction. In the example of this embodiment, the coupling lines in the first and second directions are connected at a position shifted 30 μm upwards and downwards from the nodes of the resonant electric field residing in the coupling line at terahertz wave frequencies. By deploying the two coupling lines in the second direction in this way, the coupling between the antennas in the horizontal direction is enhanced, thus achieving a higher mutual injection-locking effect. Therefore, the antenna gain is improved. The symmetry of the connection arrangement between the coupling line and the antenna is better than in the case of a single coupling line, thus a better radiation pattern effect is expected.

[0181] (Third Embodiment)

[0182] Figure 8A and 8B This is a diagram illustrating the construction of element 30 according to this embodiment. Element 30 is an antenna array in which nine antennas 300a to 300i are deployed in a 3x3 matrix. Similar to element 10 according to the first embodiment, each of the antennas 300a to 300i includes a semiconductor layer that has electromagnetic gain or nonlinearity for terahertz waves in an antenna. Figure 8A It is the same as the first embodiment Figure 4 The corresponding diagram, Figure 8B It is the same as the first embodiment Figure 5A The corresponding diagram will be provided, and the description will not be redundant.

[0183] Element 30 has a configuration that allows the coupling lines of the antennas deployed at the ends of the array to extend outward. For example, lines 3091a, 3092a, 3091c, 3092c, 3091g, 3092g, 3091i, and 3092i are connected horizontally to antennas 300a, 300c, 300g, and 300i at the four corners, and the coupling lines are extended. Similarly, lines 3093a, 3093c, 3093g, and 3093i are connected vertically to antennas 300a, 300c, 300g, and 300i at the four corners, and the coupling lines are extended. Furthermore, lines 3093d and 3093f are connected in the vertical direction, and lines 3091b, 3092b, 3091h, and 3092h are connected in the horizontal direction to antennas 300b, 300d, 300f, and 300h at the array ends and outside the four corners, and the coupling lines are extended. With this configuration, even at the array ends, the same relationship between the antenna and at least one of the coupling lines deployed in the vertical and horizontal directions is achieved. In other words, the relationship between antenna 300e and the coupling lines is consistent in layout with the relationship between each of the other antennas 300 and the coupling lines. Therefore, unwanted reflections and phase mismatches caused by the end effect are reduced, and thus enhanced phase locking and a good radiation pattern are expected. Furthermore, since the antenna and coupling lines are symmetrical in both the vertical and horizontal directions in each unit antenna, it is advantageous to simplify and facilitate the design of the antenna array. In this embodiment, symmetry between the coupling lines and the antenna in the X direction and symmetry between the coupling lines and the antenna in the Y direction are ensured. Alternatively, only one of the symmetries can be improved.

[0184] By electrically terminating the coupling lines at the ends of the single antenna and the array, the construction of element 30 can further reduce unwanted reflections and phase mismatches caused by end effects, thus further enhancing phase locking and adjusting the radiation pattern.

[0185] (Fourth Embodiment)

[0186] Figure 9A and 9B This is a diagram illustrating the construction of element 40 according to this embodiment. Figure 9A It is the same as the first embodiment Figure 4 The corresponding diagram, Figure 9B It is the same as the first embodiment Figure 5A The corresponding diagram will be provided, and redundant descriptions will not be repeated.

[0187] Component 40 has a configuration in which independent coupling lines extend from the unit antenna in both the vertical and horizontal directions. For example, coupling lines 409ef and 409de extend from antenna 400e in the vertical direction and are connected to antennas 400f and 400d, respectively. Coupling lines 4091he and 4092he extend in the horizontal direction and are connected to antenna 400h. Coupling lines 4091eb and 4092eb extend in the horizontal direction and are connected to antenna 400b. The coupling lines are adjusted such that the electrical length between the oscillators of adjacent antennas becomes an integer multiple of 2π to perform mutual injection-locking of RTDs 401a to 401i, which are oscillators of the antennas. In other words, when assuming the electrical length between the semiconductor layers of the two antennas is L1, the length L1 of the coupling lines should be set to satisfy L1 = 2π × k (k is an integer). The coupling line 409de in the first direction (vertical direction) is adjusted such that the electrical length between RTDs 401e and 401d becomes a length of 2π. The coupling lines 4091eb and 4092eb extending in the second direction are adjusted so that the electrical length between RTDs 401e and 401b becomes 4π. In this case, with coupling lines branching in the upward, downward, and leftward directions as in element 40, the electrical length between antennas can be adjusted by separately adjusting the length of each coupling line. This configuration allows for separate design of vertical and horizontal coupling lines, thereby increasing design flexibility. The configuration of element 40 further reduces unwanted reflections and phase mismatches caused by end effects by electrically terminating the coupling lines at the ends of individual antennas and the array, making this configuration further beneficial for enhancing phase locking and adjusting the radiation pattern.

[0188] (Fifth Embodiment)

[0189] In this embodiment, the application of any one of the elements according to the first to fourth embodiments to a terahertz camera system will be described. Reference will be made below. Figure 10 The terahertz camera system 1100 includes a transmitting section 1101 that radiates terahertz waves and a receiving section 1102 that detects terahertz waves. The terahertz camera system 1100 also includes a controller 1103 for controlling the operation of the transmitting section 1101 and the receiving section 1102 based on signals from an external source, and for processing images based on the detected terahertz waves or outputting images to an external source. According to any embodiment, the element may be either the transmitting section 1101 or the receiving section 1102.

[0190] The terahertz wave from the transmitting section 1101 is reflected on the subject 1105 and detected by the receiving section 1102. A camera system including the transmitting section 1101 and the receiving section 1102 is also referred to as an active camera system. In a passive camera system without the transmitting section 1101, an element according to any embodiment can be used as the receiving section.

[0191] Therefore, a camera system using elements with high antenna gain according to any one embodiment can obtain high detection sensitivity and high-quality images.

[0192] (Sixth Embodiment)

[0193] Reference Figures 11A to 12C The construction of element 50 according to this embodiment is described. Figure 11A and 11B This is a top view of component 50. Figure 11C This is an enlarged top view of a relevant part of the antenna of element 50. Figure 11D This is a modification to a part of the antenna of component 50. Figure 12A , 12B And 12C is with Figure 11A A schematic cross-sectional view of the corresponding element 50. The components and structures in element 50, except those described below, are similar to those of the antenna 100 according to the first embodiment, and therefore detailed descriptions are omitted.

[0194] like Figure 11A As shown, element 50 is an antenna array in which nine antennas 500a to 500i are deployed in a 3x3 matrix. Element 50 is an antenna array in which antenna 500a is assumed to be a unit antenna, and the unit antennas are arranged at a spacing of 0.6 wavelengths.

[0195] Component 50 has capacitors 530 deployed in the Y direction. Twelve capacitors 530 are shown in component 50. In the Y direction, capacitors 530 deployed between two antennas are referred to using the reference numerals for the two antennas, such as capacitor 530ad, etc. Figure 11A Six capacitors 530 are shown. In the Y direction, the capacitors 530 deployed around the antenna array are referred to as capacitors 530a, etc., by using the reference numerals of adjacent antennas, and the six capacitors 530 are... Figure 11A As shown in the image.

[0196] Element 50 has capacitors 531 and 532 deployed in the X direction. Capacitor 531 is deployed between any two adjacent antennas 500a to 500i, and capacitor 532 is deployed around each of antennas 500a to 500i. Capacitor 531 is located between two antennas and is referred to as capacitor 531ab, etc., using the reference numerals of the two antennas. Six capacitors 531 are shown in element 50. Capacitor 532 is located on the periphery of the antenna array and is referred to as capacitor 532a, etc., using the reference numerals of adjacent antennas. Six capacitors 521 are shown in element 50.

[0197] Antenna 500a includes multiple coupling lines serving as transmission lines for performing power transmission between adjacent antennas in the X and Y directions at an oscillation frequency of f THz. These coupling lines are also referred to as coupling lines. At least one antenna includes multiple coupling lines. At least one antenna is connected to at least three or more coupling lines. At least one antenna is connected to at least four or more different antennas via coupling lines. Here, the coupling of the coupling line to the antenna includes the case where the antenna and the coupling line are electrically connected via a capacitor, the case where the antenna and the coupling line are directly connected, and the case where the antenna and the coupling line consist of a single electrical conductor. The coupling line has a microstrip line structure. The microstrip line structure has a conductor layer, a dielectric layer, and another conductor layer. In the following description, for ease of understanding, the same reference numerals will be used to describe a conductor layer and the coupling line.

[0198] Antennas 500i, 500f, and 500c are deployed in the first row of the antenna array in this order along the Y direction. Antennas 500h, 500e, and 500b are deployed in the second row of the antenna array in this order along the Y direction. Antennas 500g, 500d, and 500a are deployed in the third row of the antenna array in this order along the Y direction. Assuming the X direction is upward, the antennas in the second row are deployed above the third row, and the antennas in the first row are deployed above the second row.

[0199] The coupling lines will be described. Initially, there are multiple conductor layers 5091, multiple conductor layers 509, and multiple conductor layers 5092, as follows: Figure 11AAs shown, each can be used as a coupling line. For ease of description, when focusing on the second row, conductor layers 5091 and 509 are deployed between the first row antennas and the second row antennas 500h, 500e, and 500b. Conductor layers 5092 and 509 are deployed between the third row antennas and the second row antennas 500h, 500e, and 500b. Here, the reference numerals for the two antennas are assigned to the conductor layers coupling the two antennas. For example, focusing on antenna 500e, antennas 500h and 500e are coupled through conductor layers 5091he and 5092he. Antennas 500e and 500b are coupled through conductor layers 5091eb and 5092eb. Antennas 500e and 500f are coupled through conductor layer 509ef. Antennas 500e and 500d are coupled through conductor layer 509de.

[0200] In other words, antenna 500h is coupled to conductor layer 5091he and conductor layer 5092he. Antenna 500e is coupled to conductor layer 5091he and conductor layer 5092he. Antenna 500e is coupled to antenna 500h via conductor layers 5091he and 5092he. Antenna 500e is coupled to conductor layer 5091eb and conductor layer 5092eb. Antenna 500b is coupled to conductor layer 5091eb and conductor layer 5092eb. Antenna 500e is coupled to antenna 500b via conductor layers 5091eb and 5092eb. Antenna 500e is coupled to conductor layer 509ef. Antenna 500f is coupled to conductor layer 509ef. Antenna 500e is coupled to antenna 500f via conductor layer 509ef. Antenna 500e is coupled to conductor layer 509de. Antenna 500d is coupled to conductor layer 509de. Antenna 500e is coupled to antenna 500d via conductor layer 509de.

[0201] when Figure 11A In the diagram, the antenna reference numerals are assumed to be xy, where x ≠ y ≠ z, and x, y, and z are each any one from a to i. Conductor layer 5091xy is located above the antenna and provides coupling in the Y direction. Conductor layer 5092xy is located below the antenna and provides coupling in the Y direction. Conductor layer 509xz is deployed between conductor layers 5091xy and conductor layer 5092xy. Here, "above" and "below" refer to positions in the X direction and respectively. Figure 11A The top and bottom sides of the paper.

[0202] This will describe one end of the antenna array. Figure 11AIn the antenna array shown, no targets are shown for the antennas at the ends, so those antennas are assigned, for example, 5091h or 5091i. However, conductor layers can be similarly deployed for other antennas. For example, when focusing on antenna 500d, conductor layer 5093d coupled to antenna 500d is not coupled to another antenna. Conductor layer 5093d can be coupled to capacitor 532d. Conductor layer 5093d can also be considered terminated.

[0203] The arrangement of the conductor layers is similar to that of antenna 500e. In other words, with this configuration, the relationship between the antennas at the ends of the antenna array and the conductor layers is equivalent to the relationship between the antennas and conductor layers inside the antenna array. In other words, antenna 500a, used as a unit element, can be considered to be repeatedly deployed between antennas 500b to 500i. This configuration increases the symmetry of the antenna array.

[0204] The relationship between the antenna and the capacitors will be described. Capacitors 530, 531, and 532 can each be used as shunt elements. Multiple capacitors 531 and 532 deployed in the X direction are coupled to the upper conductor layer of the antenna via a conductor layer serving as a coupling line. Multiple capacitors 530 deployed in the Y direction are each coupled to the upper conductor layer of the antenna. With this configuration, parasitic oscillations in the coupling line are reduced. In this specification, coupling can include capacitive coupling and direct connection.

[0205] Capacitor 531 can be coupled to multiple conductor layers. In other words, a capacitor 531 can be shared among multiple conductor layers. For example, it will be described using capacitor 531ab. Conductor layers 509ab, 5091a, 5091ad, 5092b, and 5092eb are coupled to capacitor 531ab. The same applies to capacitor 532. A capacitor 532 can be shared among multiple conductor layers. For example, conductor layers 5092a, 5092ad, and coupling line 5093a are coupled to capacitor 532a. With this configuration, it is possible to achieve a reduction in component area due to component sharing. Capacitor 530 can be coupled to multiple antennas. In other words, a capacitor 530 is shared among multiple antennas. For example, it will be described using capacitor 530ad. The conductor layers of antenna 500a and antenna 500d are coupled to capacitor 530ad. It is possible to share capacitors connected to antennas, thus reducing component area is possible. Reference will be made later. Figures 12A to 12C Describes these capacitors 530 to 532 and the configuration of the connection between the conductor layer and the capacitor.

[0206] Antenna 500a has RTDs 501a1 and 501a2 that constitute oscillating elements. Antenna 500b has RTDs 501b1 and 501b2. Antenna 500d has RTDs 501d1 and 501d2. This also applies to other antennas.

[0207] Figure 11B yes Figure 11A The image shows a top view of antenna 500a as a unit antenna of an antenna array. Antenna 500a is a patch antenna. Antenna 500a has at least a conductor layer 503a. Conductor layer 503a is biased and can be considered as the upper conductor layer because it is located at the top in a cross-section taken along the Z direction. Antenna 500a internally includes at least one or more active layers having electromagnetic wave gain or nonlinearity for terahertz waves. Specifically, antenna 500a has two active layers and a semiconductor layer 515a1 including RTD 501a1 and a semiconductor layer 515a2 including RTD 501a2. Antenna 500a is designed to oscillate at an oscillation frequency of f THz, even individually. Figure 11B In this configuration, RTD501a1, RTD501a2, conductor layer 503a, bias line 511a, and conductor layer 509a are ideally constructed symmetrically about the center of antenna 500a in both the left-right and up-down directions. Here, the left-right and up-down directions refer to... Figure 11A and 11B The X direction (A-A' direction) and Y direction (B-B' direction) in the diagram.

[0208] Capacitor 530a has a resistor 5212, a conductor layer 5224 as a component of a MIM capacitor, a wire 508a2, and a conductor layer 507a2. Capacitor 530ad has a resistor 5211, a conductor layer 5223 as a component of a MIM capacitor, a wire 508a1, and a via 507a1. Openings 505a and 505ad are openings disposed in the conductor layers. The conductor layers include bias wires 511a, 508a1, and 508a2. Hereinafter, the wires and vias may be considered as conductor layers.

[0209] Capacitor 532a has conductor layer 5221, conductor layer 5071, resistor 5191, resistor 5192, and conductor layer 5072. Capacitor 531ab has at least conductor layer 5222, resistor 5193, and resistor 5194. Here, conductor layer 5071 and conductor layer 5082 can also be considered as through-holes.

[0210] exist Figure 11BThe conductor layer 5091ad is partially shown in the figure. The conductor layer 5091ad has resistors 5511 and 5233. The conductor layer 5091ad also has another portion. This other portion is configured such that the portion shown in the figure is symmetrically arranged on the antenna 500d side with respect to the resistor 5511 line. The conductor layer 5091a has resistors 5512 and 5234. The conductor layer 5091ad is coupled to the capacitor 531ab via resistor 5233, and the conductor layer 5091a is coupled to the capacitor 531ab via resistor 5234.

[0211] Similarly, in Figure 11B The conductor layer 5092ad is partially shown in the figure. The conductor layer 5092ad has resistors 5513 and 5231. The conductor layer 5092ad also has another portion. This other portion is configured such that the portion shown in the figure is symmetrically arranged on the antenna 500d side with respect to the line of resistor 5513. The conductor layer 5092a has resistors 5514 and 5232. The conductor layer 5092ad is coupled to capacitor 532a via resistor 5231, and the conductor layer 5092a is coupled to capacitor 532a via resistor 5232.

[0212] like Figure 11B As shown, the arrangement of the components of antenna 500a is highly symmetrical. The arrangement of the components coupled to antenna 500a is also highly symmetrical. This configuration suppresses the reduction of radiated power.

[0213] Figure 11C yes Figure 11B The diagram shows a partially enlarged view of the coupling lines and capacitors of the antenna 500a. A portion of conductor layer 509ab, conductor layer 5091a, and conductor layer 5091ad are shown. A portion of conductor layer 5093a, conductor layer 5092a, and conductor layer 5092ad are also shown. The length of a portion of conductor layer 509ab is equal to the length of conductor layer 5093a, the length of conductor layer 5091a is equal to the length of a portion of conductor layer 5091ad, and the length of conductor layer 5092a is equal to the length of a portion of conductor layer 5092ad. The length of conductor layer 5091a is equal to the length of conductor layer 5092a, and the length of a portion of conductor layer 5091ad is equal to the length of a portion of conductor layer 5092ad. This configuration improves the symmetry of the antenna 500a.

[0214] Reference Figures 12A to 12C Description and Figure 11B The corresponding cross-sectional structure. Figure 12A It is along Figure 11B A schematic cross-sectional view of the line A-A' in the diagram. Figure 12BIt is along Figure 11B A schematic cross-sectional view of the line B-B' in the diagram. Figure 12C It is along Figure 11B A schematic cross-sectional view of the line C-C' in the diagram.

[0215] like Figure 12A As shown, component 50 includes a substrate 513, conductor layer 506, conductor layer 5222, conductor layer 5221, conductor layer 503a, conductor layer 509ab, and conductor layer 5093a. Component 50 has a semiconductor layer 515a1 including RTD 501a1, a semiconductor layer 515a2 including RTD 501a2, conductor layers 516a1, 516a2, 517a1, 517a2, and 514. Component 50 has dielectrics 5043, 5042, 501, and 5044. Conductor layers 517a1, 517a2, and 514 can also be considered as vias or plugs. Conductor layer 506 provides, for example, ground or ground voltage.

[0216] Conductor layer 509ab, conductor layer 506, and the dielectric between conductor layer 509ab and conductor layer 506 together form a coupling line. Conductor layer 5093a, conductor layer 506, and the dielectric between conductor layer 5093a and conductor layer 506 together form a coupling line. Conductor layer 503a, conductor layer 506, the dielectric between conductor layer 503a and conductor layer 506, RTD 501a1, and RTD 501a2 together serve as a resonator. Conductor layer 5222, conductor layer 506, and the dielectric between conductor layer 5222 and conductor layer 506 together form capacitor 531ab. Conductor layer 5221, conductor layer 506, and the dielectric between conductor layer 5221 and conductor layer 506 together form capacitor 532a. Conductor layers 509ab and 503a are arranged to overlap in the Z direction, and the length of the overlap is L1. Conductor layers 5093a and 503a are deployed overlapping in the Z direction, and the length of the overlapping portion is L2. In other words, two coupling lines and an antenna are coupled to each other. Conductor layer 509ab is connected to capacitor 531ab, and conductor layer 5093a is connected to capacitor 532a.

[0217] Reference Figure 12C Describe the connection. In Figure 12C In the figures, the same reference numerals indicate the same as... Figure 12A Similar components to those in [the document], with descriptions omitted. For example... Figure 12CAs shown, component 50 includes resistors 5191 and 5192, conductor layers 5071, 5072, 514, and 5093a. Conductor layer 5093a is connected to capacitor 532a via conductor 514. Conductor layer 5093a is connected in series with conductor layer 514, resistors 5191, 5071, and conductor layer 5221. Conductor layer 5093a is also connected in series with conductor layer 514, resistors 5192, 5072, and 5221. Conductor layers 5071, 5072, and 514 are also referred to as through-holes, plugs, etc.

[0218] exist Figure 12B In the figures, the same reference numerals indicate the same as... Figure 12A and 12C Similar components are omitted from the description. Component 50 has conductor layers 507a1, 507a2, 508a1, 508a2, 511a, 512, 5223, and 5224. Component 50 has resistors 5211 and 5212. Conductor layers 507a1, 507a2, and 512 are also referred to as through-holes or plugs. Conductor layer 503a is connected to conductor layer 5223 via conductor layers 507a1, 508a1, resistor 5211, and conductor layer 512. In other words, conductor layer 503a is connected to capacitor 530ad. Conductor layer 503a is connected to conductor layer 5224 via conductor layers 507a2, 508a2, resistor 5212, and conductor layer 512. In other words, conductor layer 503a is connected to capacitor 530a. Here, in two regions, conductor layer 511 is deployed separately from conductor layer 512. Conductor layer 511a is connected to at least one of conductor layers 508a1 and conductor layer 508a2 at least on the proximal and distal sides of the paper. The proximal and distal sides of the paper are positions in the X direction. In other words, in a cross-section including the Y and Z directions, conductor layer 511a has openings 505ad and 505a.

[0219] The distances between the aforementioned conductor layers and the top surface of the substrate 513 vary. For example, Figures 12A to 12CThe relevant components are constructed as follows: The first layer includes conductor layer 506. The second layer includes conductor layers 5221, 5222, 5223, and 5224. The third layer includes conductor layers 512, 5071, and 5072. The fourth layer includes conductor layers 508a1, 508a2, 5191, 5192, and 511a. The fifth layer includes conductor layers 508a1, 508a2, 5191, 5192, and 511a. The sixth layer includes conductor layers 507a1 and 507a2. The seventh layer includes conductor layer 503a. The eighth layer includes conductor layer 514. The ninth layer includes conductor layers 509ab and 5093a. The position of the components can be changed by selecting optional manufacturing methods.

[0220] exist Figures 12A to 12C In this configuration, conductor layer 506 is configured to be shared by components including capacitors, coupling lines, etc. Conductor layer 506 is a single conductor layer capacitor deployed across the entire surface of element 50. By using conductor layer 506 configured in this way, fluctuations in the supplied voltage are reduced.

[0221] Reference Figures 11A to 12C The construction of element 50 is further described. As described above, multiple coupling lines have a microstrip structure. Each coupling line consists of a conductor layer, a dielectric layer, and another conductor layer. Each coupling line is, for example, a microstrip line with the following structure, wherein dielectrics 504 and 5044 are sandwiched between conductor layers 509a, 509ab, 5093a, 5091ad, 5091a, 5092ad, and 5092a, as well as conductor layers 506 and 511a. Conductor layer 511a can also be considered as a bias line operating as a ground conductor at f THz. Antenna 500a consists of a patch antenna and microstrip lines connected to the patch antenna, and is designed to oscillate even individually at an oscillation frequency of f THz. Conductor layer 506 can be considered as the first conductor layer.

[0222] The patch antenna of antenna 500a is coupled to conductor layer 509a via AC coupling (capacitive coupling). For example, as Figure 11B and 12AAs shown in the plan view, the conductor layers 503a and 509ab of antenna 500a overlap each other around the radiating end of antenna 500a, separated by an insulator. The overlap length is L1. The length L1 is assumed to be, for example, 5 μm. The overlapping portion of the conductor layers is a metal-insulator-metal (MIM) capacitor structure, laminated in the order of conductor layer 503a, dielectric layer 5044, and conductor layer 509ab. The capacitance value is, for example, 20 fF. Conductor layers 503a and 509ab are open-circuited in the DC and low-frequency range below f THz (below or equal to 10 GHz), and isolation between antennas is ensured. On the other hand, in the frequency band of the oscillation frequency f THz, the coupling strength between antennas is adjusted by adjusting the impedance using capacitors. This also applies to the other conductor layers 5091ad, 5091a, 5092ad, 5092a, and 5093a.

[0223] like Figure 11B As shown, in antenna 500a, the coupling line branches into three directions—upward, rightward, and leftward—at each radiating end, and each branch of the coupling line is independently connected to one of the six conductor layers. These six conductor layers are conductor layers 5091ad, 5091a, 5092ad, 5092a, 509ab, and 5093a. Therefore, two antennas and one coupling line are connected in a one-to-one relationship. This configuration allows for individual and independent adjustment of the length and width of the group consisting of two antennas and one coupling line, making it suitable for separately adjusting the electrical length and impedance between any two adjacent antennas in the antenna array. Thus, the vertical and horizontal coupling lines are allowed to be adjusted separately, increasing design flexibility. Figure 11C As shown, the connecting portion of the conductor layer 509a at the radiating end of the antenna is presumably configured such that multiple coupling lines merge and connect at a single point, or configured to increase the coupling amount by increasing the area of ​​the connecting portion in the antenna. The configuration can be selected according to the application requirements.

[0224] The width of conductor layer 509a is a parameter for adjusting the impedance of the microstrip line and is designed from the viewpoint of matching with antenna 500a and reducing transmission loss. The length of conductor layer 509a is preferably designed such that the electrical length between RTDs located at the same position in adjacent antennas is an integer multiple of 2π. In the case of antenna 500a, conductor layer 509ab extending in the X direction has a length such that the electrical length between RTD 501a1 and RTD 501b1 becomes 2π. Therefore, Figure 11CA portion of conductor layer 509ab shown is set to half the length of conductor layer 509ab (electrical length π). A portion of conductor layer 509ab is set to the same length as conductor layer 5093a. Similarly, the Y-direction extending portion of conductor layer 5091ad and the length of conductor layer 5092ad are set to half the electrical length 4π between RTD 501a1 and RTD 501d1 and between RTD 501a2 and RTD 501d2, i.e., the electrical length becomes 2π. The length of conductor layer 5091a can be set to at least one of the lengths of half conductor layer 5091ad and half conductor layer 5092ad. Conductor layer 5092a can be set to at least one of the lengths of half conductor layer 5091ad and half conductor layer 5092ad.

[0225] Conductor layer 509a includes a shunt assembly connected to a node of a resonant electric field having an oscillation frequency of f THz for mode stabilization. For example... Figure 11C As shown, conductor layer 509a and the shunt assembly are connected to each other via via 514. The shunt assembly has resistors and capacitors. The shunt assembly is, for example, a snubber circuit. Resistors 5191, 5192, 5231, 5232 and capacitor 532a are connected in series. Resistors 5193, 5194, 5233, 5234 and capacitor 531ab are connected in series. The resistors have, for example, 20Ω and are made of a thin film such as TiW. The capacitors have, for example, 20pF and are MIM capacitors. Capacitor 532a has a capacitor structure in which dielectric 5043 is sandwiched between conductor layers 5221 and 506. Capacitor 531ab has a capacitor structure in which dielectric 5043 is sandwiched between conductor layers 5222 and 506. Therefore, it is possible to suppress multimode oscillations in the antenna array by performing an AC short circuit on the radio frequency outside the oscillation frequency f THz to provide low impedance. In conductor layer 509a, resistors 5511, 5512, 5513, and 5514 are connected at the nodes of the resonant electric field with an oscillation frequency of f THz. Each of these resistors has a resistance value of, for example, 20 Ω and is made of a TiW thin film. Therefore, the mode is stabilized by losing frequency and phase difference components other than the oscillation frequency f THz.

[0226] These components, deployed at the nodes and antinodes of the resonant electric field with an oscillation frequency of f THz, also serve as electrical terminals at the ends of conductor layer 509a of antenna 500a, which is a unit antenna. For example, the case where no antenna is connected to antenna 500a in the vertical direction (X direction) will be described. The end of conductor layer 509ab not connected to conductor layer 503a is an open-circuit terminal. Furthermore, the end of conductor layer 5093a not connected to conductor layer 503a is also an open-circuit terminal. When an open-circuit terminal is present, the resonant characteristics are affected. Similar to the case of antenna 500a, by AC short-circuiting this end using a shunt component connected at the node of the resonant electric field at f THz to terminate it, unwanted reflections and phase mismatch are reduced, resulting in stable resonance at frequency f THz. This also applies to the case where no antenna is connected in the left-right direction (Y direction). Resistors connected to conductor layers 5091ad, 5091a, 5092ad, and 5092a, respectively, serve as terminals for adjusting impedance. The resistor is located at a node of the resonant electric field with an oscillation frequency of f THz. This embodiment can be a configuration suitable for at least one of stabilizing oscillation, enhancing phase locking, and adjusting the radiation pattern by electrically terminating the coupling lines at the ends of a single antenna and array to reduce the effects at the ends.

[0227] Next, the bias lines used to power RTDs 501a1 and 501a2 will be described. The bias lines are conductor layers 511. In antenna 500a, the bias lines are also constructed to be symmetrical about the vertical and horizontal directions of the paper with respect to the center (centroid) of antenna 500a. The vertical and horizontal directions are the X and Y directions, and can be considered as A-A' and B-B' directions. Conductor layers 507a1 and 507a2, connected at the nodes of the resonant electric field with f THz in conductor layer 503a, are connected to conductor layer 511a, which serves as a common wiring line, via lines 508a1 and 508a2. Each of lines 508a1 and 508a2 has a pencil-like tapered shape, resulting in a narrower wiring width at the connection point with the corresponding conductor layer 507a1 or 507a2. The wiring width of each of lines 508a1 and 508a2 widens as it approaches the conductor layer 511a, which serves as a common wiring line. The length of the narrow portion of the wiring width is less than or equal to λTHz / 10. When the connection width of each of conductor layers 507a1 and 507a2 is narrow, interference and loss between the bias line and the resonant electric field with fTHz in the antenna are reduced. Due to the gradually widening wiring width, the wiring resistance decreases from DC to the low-frequency band (<100MHz), thus suppressing variations in the operating voltage of each antenna. This wiring structure effectively suppresses operating voltage variations caused by the decrease in wiring resistance in the low-frequency band and suppresses interference and loss in the antenna array at fTHz. Therefore, this wiring structure is suitable for stable operation of the antenna array with mutual injection-locking. Lines 508a1 and 508a2 are connected to a buffer circuit. The buffer circuit has a structure in which the conductor layer 5223 of resistor 5211 and capacitor 530a are connected in series. The buffer circuit has a structure in which the conductor layer 5224 of resistor 5212 and capacitor 530ad are connected in series. Resistors 5211 and 5212 each have, for example, a capacitance of 15Ω and are each made of a TiW thin film. Capacitor 530ad is composed of conductor layer 5223, conductor layer 506 and dielectric 5043 therebetween. Capacitor 530a is composed of conductor layer 5224, conductor layer 506 and dielectric 5043 therebetween. The capacitance values ​​of capacitors 530a and 530ad are each, for example, 10pF. Using the buffer circuit, conductor layer 511a, lines 508a1 and 508a2 near the RTD are AC short-circuited and have low impedance in a frequency band below or equal to 100GHz. Therefore, parasitic oscillations below or equal to 100 GHz caused by the inductance of the bias line can be reduced.

[0228] Figure 11BThis is an antenna array in which antennas 500a, acting as unit antennas, are arranged in a 3x3 configuration with a constant spacing of 0.6 wavelengths, and adjacent antennas are connected via coupling lines. Through the connection of the coupling lines, the RTDs 501a1 and 501a2 of each antenna undergo phase injection-locking. All adjacent conductor layers 511a are also connected to form a common conductor layer 511, i.e., a common bias line. Using the common bias line, a bias signal can be supplied to the RTDs of the antennas from a common power supply. Preferably, buffer circuits are connected for adjacent antennas to maintain symmetry. For example, for antennas 500a and 500d, a buffer circuit 530ad is connected to improve symmetry. The buffer circuit 530ad consists of resistors and MIM capacitors. The buffer circuit 530ad is connected to and connected to the common conductor layer 511 for each antenna. The buffer circuit 530ad is deployed between adjacent antennas. Similar to the case of the buffer circuit 530ad, capacitors can be shared between adjacent antennas to increase integration by reducing component layout. The common conductor layer 511 of the antenna array is AC short-circuited in the frequency band below or equal to 100 GHz, wherein a buffer circuit 530ad is deployed for each antenna, including the buffer circuit 530ad to provide low impedance, which results in the suppression of low-frequency oscillations between antennas. In other words, at least one buffer circuit is connected to multiple antennas.

[0229] Antenna 500e is coupled to each of four different antennas 500f, 500d, 500h, and 500b in both the vertical and horizontal directions via coupling lines. Antenna 500e is connected one-to-one with each of the antennas 500f and 500d arranged in the vertical direction via independent coupling lines. Antenna 500e is connected one-to-one with each of the antennas 500h and 500b arranged in the horizontal direction via two independent coupling lines. In other words, antenna 500e is connected to a total of six coupling lines. Coupling line 5091eb extending from antenna 500e is connected unbranched to the adjacent antenna 500b. In this way, using an antenna array in which each has symmetrically deployed antenna components and coupling lines arranged regularly, large-scale M-by-N arrays (M and N are the number of antennas and are natural numbers) can be designed with high accuracy and efficiency by using the impedance of the unit antenna as a basis. Because the coupling lines are routed in both the vertical (X-direction) and horizontal (Y-direction) directions, mutual injection-locking between adjacent antennas is enhanced, making directional control via antenna array synchronization easy.

[0230] Figure 11D This is a schematic plan view illustrating a modification of this embodiment. Components 51 and 52 each represent... Figure 11BAntenna 500a is located at the upper part in the X direction. In other words, elements 51 and 52 each represent the coupling portion between conductor layer 503a, coupling line 5091ad, coupling line 509ab, and coupling line 5091a. Figure 11B In element 51, the ends of the three coupling lines are arranged separately from each other; while in element 52, the ends of the three coupling lines are integrated. In other words, a coupling line coupled to antenna 500a can be considered to branch into two or more lines, such as three. In element 52, compared to element 51, the three branches are spaced apart from each other. In other words, Figure 11B The ends of the three coupling lines can be considered as being connected by another conductor layer extending in the Y direction.

[0231] In each of elements 51 and 52, in a plan view, a coupling line can be considered to be positioned inside the outer edge of the antenna to be coupled and can be considered to branch into three coupling lines outside the outer edge. The construction of each of elements 51 and 52 can be considered, for example, the antenna and the three coupling lines connected at a single connection point. Figure 11B In the plan view, three coupling lines are positioned inside the outer edge of the antenna to be coupled, and these coupling lines are spaced apart from each other. In other words, in Figure 11B In this configuration, the antenna and three coupling lines can be considered as being connected at three connection points. Here, a connection point can be a coupling point, and a connection can be a coupling. Using this configuration, the three coupling lines can be synchronized.

[0232] about Figure 11A The antenna array layout is not limited to 3x3, but can be expanded to 4x4, 5x5, etc.

[0233] (Seventh Embodiment)

[0234] Figure 13A This is a top view of element 60 modified according to the sixth embodiment. Components other than those labeled with reference numerals are... Figure 11A The components shown are equivalent.

[0235] exist Figure 13A In the antenna array, the antenna 600e at the center has two or more connectable adjacent antennas in the vertical direction (X direction) and two or more connectable adjacent antennas in the horizontal direction (Y direction). Therefore, antenna 600e is connected to each adjacent antenna via a corresponding coupling line from among the coupling lines 609ef, 609df, 6091he, 6092he, 6091eb, and 6092eb extending in the horizontal and vertical directions. The construction of antenna 600e is similar to... Figure 11AThe antenna 500e shown is similar. On the other hand, antennas 600a to 600d, 600f to 600i at the array ends do not have coupling lines in the direction where adjacent antennas are not deployed. The length and impedance of each coupling line of element 60 can be adjusted so that the oscillation frequency f THz is stably synchronized even when no coupling lines are deployed at nodes or antinodes. Therefore, even if the number of coupling lines in each antenna is reduced, the fluctuation of the resonant characteristics of frequency f THz is reduced. In element 60, for example, at the upper and lower ends of the antenna, two adjacent antennas and coupling lines are connected in a one-to-one relationship and are connected independently. The upper and lower ends of the antenna are the two ends of the antenna in the X direction. Therefore, unnecessary coupling lines can be omitted without changing the resonant characteristics of f THz. In element 60, for example, at the right and left ends of the antenna, two adjacent antennas and coupling lines are connected in a one-to-two-to-one relationship. The right and left ends of the antenna are the antenna ends in the Y direction.

[0236] In antennas deployed on the periphery of an antenna array, since no coupling lines are deployed on the periphery of the antenna array, the end of each coupling line is coupled to any one of the nine antennas. Utilizing a THz band microstrip line structure, conductor losses occur due to the skin effect and dielectric losses due to increased tanδ, thus increasing power transmission losses. Therefore, as the power transmission used for coupling increases, a trade-off can arise between synchronization and loss. Using the construction according to this embodiment, coupling lines that do not contribute to coupling are reduced, thus reducing losses. It is possible to achieve both injection-locked directional control and increased frontal gain due to reduced transmission losses. By eliminating the open ends of each coupling line, the integration of the aforementioned termination components becomes unnecessary. Therefore, it is possible to reduce characteristic variations due to manufacturing errors and lower manufacturing costs.

[0237] Figure 13B This is an enlarged top view of element 70, where the antenna array layout of element 60 is extended to a 4x4 array. Figure 13B Only the components are shown Figure 13A The antenna's conductor layer and the conductor layer constituting the coupling line. By using, for example... Figure 13A The unit antenna shown, consisting of highly symmetrical antennas and coupling lines, can be extended to an M-by-N array (where M and N are natural numbers), using the same design rules as low-order antenna arrays, whether odd or even. Here, it is assumed that the centroid of the antenna array is indicated by point O.

[0238] exist Figure 13B In this context, element 70 includes antennas 700a to 700p. For example... Figure 13AAs shown, in element 70, multiple antennas are coupled via coupling lines 709, 7091, and 7092. This configuration also reduces losses when the antennas are synchronized.

[0239] (Eighth Embodiment)

[0240] In this embodiment, modifications to element 70, which is a modification of the seventh embodiment, will be described. Figures 14A to 20B It shows Figure 13B The coupling line of element 70 shown is modified. (With) Figure 13B The situation is the same. Figures 14A to 20B Only the conductor layer constituting the antenna and the conductor layer constituting the coupling line are shown.

[0241] Figures 14A to 15B This configuration differs from element 70 in that it alters the number of coupling lines provided in the Y direction. This configuration allows for injection-locking due to coupling between antennas and reduces transmission loss. The reduction in transmission loss increases radiated power.

[0242] Figure 14A This is a top schematic diagram showing element 71. Six coupling lines extending in the Y direction are reduced from element 70. Specifically, coupling lines 7092dh, 7092hl, 7092lp, 7091ae, 7091ei, and 7091im of element 70 are not deployed in element 71. Assuming the unit array is a 2x2 array, unit array UA1 includes antennas 700d, 700c, 700g, and 700h. Antennas 700d, 700c, 700g, and 700h are ring-coupled via coupling lines 7091dh, 709cd, 7092cg, and 709gh. Furthermore, antennas 700c and 700g are ring-coupled via coupling line 7091cg. Unit array UA2 includes antennas 700a, 700b, 700e, and 700f. Antennas 700a, 700b, 700e, and 700f are ring-coupled via coupling lines 7091bf, 709ab, 7092ae, and 709ef. Furthermore, antennas 700f and 700b are ring-coupled via coupling line 7092bf. The arrangement of the antennas and coupling lines in unit array UA1 can be considered a mirror-symmetric arrangement with that in unit array UA2. This also applies to other unit arrays, thus the antenna arrays exhibit high symmetry.

[0243] Figure 14BThis is a top schematic diagram showing element 72. Six coupling lines extending in the Y direction are further reduced from element 71. Specifically, coupling lines 7092bf, 7092fj, 7092jn, 7091cg, 7091gk, and 7091ko of element 71 are not deployed in element 72. Assuming the unit array is a 2x2 array, the unit array UA1 includes antennas 700d, 700c, 700g, and 700h. Antennas 700d, 700c, 700g, and 700h are ring-coupled via coupling lines. Antennas 700h, 700g, 700k, and 700l are ring-coupled via coupling lines. Antennas 700l, 700k, 700o, and 700p are ring-coupled via coupling lines. This also applies to other unit arrays, thus the antenna array has high symmetry.

[0244] Figure 15A This is a top schematic diagram showing element 73. Six coupling lines extending in the Y direction are further reduced from element 71. Specifically, coupling lines 7092cg, 7092gk, 7092ko, 7091bf, 7091fj, and 7091jn of element 71 are not deployed in element 73. Assuming the unit array is a 2x2 array, the unit array UA1 includes antennas 700d, 700c, 700g, and 700h. Antennas 700d and 700c are coupled via coupling line 709cd, and antennas 700g and 700h are coupled via coupling line 709fh. Antennas 700c and 700g are coupled via coupling line 7091cg, and antennas 700h and 700d are coupled via coupling line 7091dh. Unit array UA2 includes antennas 700a, 700b, 700e, and 700f. Antennas 700a and 700b are coupled via coupling line 709ab, and antennas 700e and 700f are coupled via coupling line 709ef. Antennas 700a and 700e are coupled via coupling line 7092ae, and antennas 700b and 700f are coupled via coupling line 7092bf. The arrangement of antennas and coupling lines in unit array UA1 and unit array UA2 can be considered as a mirror image of each other. This also applies to other unit arrays, thus the antenna arrays exhibit high symmetry.

[0245] Figure 15BThis is a top schematic diagram showing element 74. The six coupling lines extending in the Y direction are further reduced from element 73. Specifically, coupling lines 7092bf, 7092fj, 7092jn, 7091cg, 7091gk, and 7091ko of element 73 are not deployed in element 74. For element 74, a unit array can also be defined as in other examples. The arrangement of the antennas and coupling lines in unit array UA1 can be considered a mirror-symmetric arrangement with that in unit array UA2. This also applies to other unit arrays, thus the antenna array has high symmetry.

[0246] For example, Figure 15A This illustrates an arrangement that balances synchronization and loss by deploying the same number of coupling lines in both the X and Y directions and reducing the difference in the number of coupling lines connecting the antennas at the ends and the center of the antenna array. Figures 14A to 15B In this context, when the centroid of the antenna array is taken, the arrangement of the antenna array and the coupling lines can be symmetrical.

[0247] Figures 16A to 18A These are further modifications. These modifications can be achieved by extending the design rules for unit arrays to M x N arrays (where M and N are both even numbers). In this modification, one antenna is responsible for constructing the coupling between the unit arrays, for example, Figure 16A , 17A Examples include 18A. This construction reduces the number of coupling lines that facilitate coupling, thus potentially reducing changes in synchronization between the ends and center of the array.

[0248] Figure 16AThis is a top schematic diagram showing element 75. Coupling lines extending in the X and Y directions decrease from element 70. Element 75 includes four unit arrays UA1 to UA4. Unit array UA1 includes antennas 700c, 700d, 700g, and 700h. Unit array UA2 includes antennas 700a, 700b, 700e, and 700f. Unit array UA3 includes antennas 700i, 700j, 700m, and 700n. Unit array UA4 includes antennas 700k, 700l, 700o, and 700p. Each of unit arrays UA1 to UA4 includes one coupling line 7091, one coupling line 7092, and two coupling lines 709. For example, unit array UA1 will be described. Antennas 700c and 700d are coupled via coupling line 709cd, and antennas 700d and 700h are coupled via coupling line 7091dh. Antennas 700h and 700g are coupled via coupling line 709gh, and antennas 700g and 700c are coupled via coupling line 7092cg. In other words, the four antennas are ring-coupled by four coupling lines. This also applies to the other unit arrays UA2 through UA4. One antenna in each unit array is ring-coupled. Specifically, antennas 700g and 700f are coupled via coupling line 709fg, and antennas 700f and 700j are coupled via coupling line 7092fj. Antennas 700j and 700k are coupled via coupling line 709jk, and antennas 700k and 700g are coupled via coupling line 7091gk.

[0249] Figure 16B This is a top schematic diagram showing element 76. The coupling lines extending in the X and Y directions decrease from element 70. Specifically, coupling lines 7091hl, 7092hl, 7091ei, and 7092ei of element 70 are not deployed in element 76. In element 76, the unit array is 1x2 (1 row, 2 columns), and the two antennas are ring-coupled via coupling lines. Unit array UA1 includes antennas 700d and 700h. Antennas 700d and 700h are ring-coupled via coupling lines 7091dh and 7092dh. Unit array UA2 includes antennas 700c and 700g. Antennas 700c and 700g are ring-coupled via coupling lines 7091cg and 7092cg. Antennas 700d and 700c are coupled via coupling line 709cd, and antennas 700g and 700h are coupled via coupling line 709gh. This also applies to the connection relationships of another 1x2 unit array and another 2x2 unit array. Figure 16ASimilarly, in this configuration, one antenna in each unit array is ring-coupled. Specifically, antennas 700g and 700f are coupled via coupling line 709fg, and antennas 700f and 700j are coupled via coupling line 7092fj. Antennas 700j and 700k are coupled via coupling line 709jk, and antennas 700k and 700g are coupled via coupling line 7091gk. Furthermore, antennas 700g and 700k are coupled via coupling line 7092gk, and antennas 700f and 700j are coupled via coupling line 7091fj. Using this configuration, the unit array is coupled while maintaining the symmetry of a 1x2 unit array.

[0250] Figure 17A This is a top schematic showing element 77. The coupling lines extending in the X and Y directions decrease from element 70. In element 77, the unit array is 1x2, and the two antennas are circumcoupled via coupling lines. Unit array UA1 includes antennas 700d and 700h. Antennas 700d and 700h are circumcoupled via coupling lines 7091dh and 7092dh. Unit array UA2 includes antennas 700c and 700g. Antennas 700c and 700g are circumcoupled via coupling lines 7091cg and 7092cg. Antennas 700g and 700h are coupled via coupling line 709gh; however, antennas 700d and 700c are not coupled via coupling line 709cd. This also applies to the connection relationships of another 1x2 unit array and another 2x2 unit array. One antenna in each unit array is circumcoupled with each other. Specifically, antennas 700g and 700f are coupled via coupling line 709fg, and antennas 700f and 700j are coupled via coupling line 7092fj. Antennas 700j and 700k are coupled via coupling line 709jk, and antennas 700k and 700g are coupled via coupling line 7091gk. Furthermore, antennas 700g and 700k are coupled via coupling line 7092gk, and antennas 700f and 700j are coupled via coupling line 7091fj. The arrangement of the antennas and coupling lines in the antenna array can be point-symmetric with respect to the centroid of the antenna array.

[0251] Figure 17B This is a top view showing component 78. In component 78, with... Figure 16ASimilar to element 75, the unit array is 2x2, and the four antennas are ring-coupled via coupling lines. Antennas 700g, 700f, 700j, and 700k are coupled via coupling lines 7091gk, 709fg, 709jk, and 7092fj shown in element 75. Furthermore, antennas 700g, 700f, 700j, and 700k are coupled via coupling lines 7092gk and 7091fj.

[0252] Figure 18A This is a top view showing component 79. In component 79, with... Figure 16A Similar to element 75, the unit array is 2x2, and the four antennas are ring-coupled via coupling lines. Furthermore, as with element 75, antennas 700g, 700f, 700j, and 700k in each unit array are coupled via coupling lines. The difference from element 75 is that in each of unit arrays UA1 to UA4, coupling lines 7091 and 7092 are interchanged. Specifically, in unit array UA1, antennas 700d and 700h are coupled via coupling line 7092dh, and antennas 700c and 700g are coupled via coupling line 7091cg. Antennas 700g and 700k are coupled via coupling line 7092gk, and antennas 700j and 700f are coupled via coupling line 7091fj. Using this configuration, it is also possible to provide antenna arrays with high symmetry.

[0253] Here, in Figure 17A and 17B In this case, it is possible to reduce the variation in coupling at the ends and center of the antenna array by changing the number of coupling lines coupled to the selected antennas located at the ends or center.

[0254] Figures 18B to 20B This is a further modification. The inventors discovered through research that the following three conditions are important. One condition is that the number of coupling lines connected in the X direction is close to the number of coupling lines connected in the Y direction. Another condition is that the difference between the number of coupling lines connected to the antennas at the ends of the antenna array and the number of coupling lines connected to the antennas at the center of the antenna array is reduced. A third condition is that the difference between the number of coupling lines connected to the two radiating ends of the antenna is reduced. Using these configurations, the coupling in the vertical direction is balanced with the coupling in the horizontal direction, and the synchronous change between the ends and the center of the antenna array is reduced. For example, Figure 18B , 19A The 19B and 19B are constructed with priority given to symmetry in the X and Y directions to provide good orientation, while Figure 20A and 20BThe preferred design is one that reduces losses due to a reduction in the number of coupling lines.

[0255] Figure 18B This is a top schematic diagram showing element 80. In element 80, the unit array is 1x2. The antenna array includes unit arrays UA1 to UA12. In element 80, the antennas included in the unit arrays include the antennas of adjacent unit arrays and are deployed such that multiple unit arrays overlap each other. Unit array UA1 includes antennas 700d and 700h. Unit array UA2 includes antennas 700c and 700g. Unit array UA3 includes antennas 700b and 700f. Unit array UA4 includes antennas 700a and 700e. Unit array UA5 includes antennas 700h and 700l. Unit array UA6 includes antennas 700g and 700k. Unit array UA7 includes antennas 700f and 700j. Unit array UA8 includes antennas 700e and 700i. Unit array UA9 includes antennas 700l and 700p. Unit array UA10 includes antennas 700k and 700o. Unit array UA11 includes antennas 700j and 700n. Unit array UA12 includes antennas 700i and 700m. Unit arrays UA2, UA3, UA6, UA7, UA10, and UA11 are coupled via two coupling lines 709, 7091, and 7092, which are coupled to the upper and lower sides of each antenna. This configuration is consistent with... Figure 13B The structures are similar. However, for unit arrays UA1, UA5, and UA9, a coupling line 709 coupled to the lower end of the antenna is coupled to a coupling line 7092 coupled to the adjacent antenna. For unit arrays UA4, UA8, and UA12, a coupling line 709 coupled to the upper end of the antenna is coupled to a coupling line 7091 coupled to the adjacent antenna.

[0256] Figure 19A This is a top view showing element 81. In element 81, the unit array is 1x2, as shown below. Figure 18B The case of element 80 is shown. Similar to element 80, the antenna array comprises unit arrays UA1 to UA12. In element 81, the antenna is coupled in the X direction via coupling line 709. Coupling of the antenna in the Y direction is performed via either coupling line 7091 or coupling line 7092. In other words, either coupling line 7091 or coupling line 7092 is deployed between adjacent antennas in the Y direction. With this configuration, it is also possible to provide an antenna array with high symmetry.

[0257] Figure 19BThis is a top view showing component 82. In component 82, with... Figure 19A The same applies to element 81, where the unit array is 1x2, and the antenna coupling in the Y direction is performed through either coupling line 7091 or coupling line 7092.

[0258] Figure 20A This is a top view showing component 83. In component 83, with... Figure 19A The same applies to element 81, where the unit array is 1x2, and the antenna coupling in the Y direction is performed through either coupling line 7091 or coupling line 7092.

[0259] Figure 20B This is a top view showing component 84. In component 84, with... Figure 19A Similar to element 81, the unit array is 1x2, and the antennas in the Y direction are coupled via either coupling line 7091 or coupling line 7092. However, some of the coupling lines for coupling the antennas in the Y direction are omitted. For example, in each of unit arrays UA2, UA4, UA5, UA7, UA10, and UA12, the two antennas deployed in the Y direction are coupled via coupling line 7091 or coupling line 7092. However, in each of unit arrays UA1, UA3, UA6, UA8, UA9, and UA11, the two antennas deployed in the Y direction are not coupled.

[0260] Figure 21 This is a schematic diagram illustrating the correlation between the degree of synchronization between antennas in the aforementioned 4x4 antenna array and the radiated power of each antenna. The horizontal axis, "degree of synchronization," represents the frontal gain of the antenna array increasing proportionally to the power of the number of antennas. The vertical axis, "radiated power / antenna," represents the magnitude of the oscillating power radiated from a single antenna in all directions. For example, in the case of an ideal antenna array with lossless coupling lines, mutual injection-locking can be achieved losslessly, thus realizing both the maximum radiated power of each antenna and the frontal gain enhancement (square law) resulting from directivity sharpening. For example, the radiated power is 0.3 mW. This is shown as Comparative Example 2.

[0261] In practice, power transmission through microstrip lines incurs losses, which are particularly significant in the THz band. Therefore, as with connection examples 4, 5, and 1, transmission losses increase with the number of coupling lines. The radiated power of each antenna tends to decrease with the amount of loss. On the other hand, increasing the number of coupling lines enhances the coupling between antennas, thus sharpening the directivity due to mutual injection-locking of the antenna array. Therefore, by increasing the number of coupling lines, the frontal gain can be increased approximately in a square law-like manner with respect to the number of antennas. The case without coupling lines is shown as Comparative Example 1. In this case, there is no loss in the power transmitted between antennas via the coupling lines, thus maximizing the radiated power of each antenna. However, the coupling between antennas is weak, and mutual injection-locking does not occur, so no sharpening of directivity occurs. Therefore, the increase in frontal gain is proportional to the number of antennas, and thus the "degree of synchronization" follows a power-law. The aforementioned antenna array can achieve both the desired radiated power and directivity by adjusting and designing the number of coupling lines in the X and Y directions. Increasing the frontal gain is possible. Here, Connection Example 1 is... Figure 13A The construction, connection example 4 is Figure 15B The construction, connection example 5 is Figure 15A The structure of.

[0262] (Other embodiments)

[0263] The embodiments of the present invention have been described above; however, the present invention is not limited to these embodiments. Various modifications and variations can be made within the scope of the present invention.

[0264] For example, the above embodiments are described with the premise that the carrier is an electron; however, the configuration is not limited to this. Holes can be used as carriers. The materials of the substrate and dielectric can be selected according to the application. Semiconductor layers such as silicon, gallium arsenide, indium arsenide, and gallium phosphide, glass, ceramics, and resins such as polytetrafluoroethylene and polyethylene terephthalate can be used.

[0265] Furthermore, in the above embodiments, a square patch antenna is used as a terahertz wave resonator; however, the shape of the resonator is not limited to this. For example, a resonator with a structure using patch conductors of polygonal, circular, or elliptical shapes, such as rectangles and triangles, can be used.

[0266] The number of differential negative resistive elements integrated into the component is not limited to one, and the resonator can have multiple differential negative resistive elements. The number of lines is not limited to one, and multiple lines can be provided. By using the components described in the above embodiments, oscillation and detection of terahertz waves are possible.

[0267] In each of the above embodiments, a double-barrier RTD made of InGaAs / AlAs grown on an InP substrate is described as an RTD. However, the construction is not limited to these structures and materials. The element according to the invention can even have other combinations of structures and materials. For example, an RTD with a triple-barrier quantum well structure or an RTD with a quadruple or more barrier quantum wells can be used.

[0268] The following combinations can each be used as materials for RTDs.

[0269] • GaAs / AlGaAs, GaAs / AlAs, and InGaAs / GaAs / AlAs are formed on a GaAs substrate.

[0270] • InGaAs / InAlAs, InGaAs / AlAs, and InGaAs / AlGaAsSb are formed on an InP substrate.

[0271] • InAs / AlAsSb and InAs / AlSb are formed on an InAs substrate.

[0272] • SiGe / SiGe, formed on a Si substrate

[0273] The aforementioned structures and materials should be selected as needed based on the desired frequency, etc.

[0274] The construction of this embodiment eliminates the upper limit on the number of antennas arranged in the antenna array and provides a significant improvement in directivity and frontal intensity due to the increase in the number of antennas. Therefore, using the construction of the above embodiment, it is possible to provide suitable components capable of generating and detecting terahertz waves with higher efficiency.

[0275] The embodiments of the present invention are not limited to those described above. Various changes or modifications may be applied without departing from the spirit and scope of the invention. Therefore, the following claims are appended to illustrate the scope of the invention.

[0276] This application claims priority to Japanese Patent Application No. 2020-179542, filed on October 27, 2020, and Japanese Patent Application No. 2021-171694, filed on October 20, 2021, which are incorporated herein by reference.

Claims

1. An element comprising an antenna array in which a plurality of antennas are deployed, each antenna comprising: First conductor layer, A semiconductor layer, electrically connected to the first conductor layer, generates or detects terahertz waves. The second conductor layer is electrically connected to the semiconductor layer and is opposite to the first conductor layer across the semiconductor layer. The dielectric layer is located between the first conductor layer and the second conductor layer, wherein The antenna array includes a first antenna, a second antenna, a third antenna, a fourth antenna, and a fifth antenna. The second, first, and third antennas are arranged in this order along the first direction. The fourth, first, and fifth antennas are arranged in this order along a second direction intersecting the first direction. The second conductor layer of the second antenna is connected to the second conductor layer of the first antenna via a first coupling line extending in a first direction. The second conductor layer of the first antenna is connected to the second conductor layer of the third antenna via a second coupling line extending in the first direction. The second conductor layer of the fourth antenna is connected to the second conductor layer of the first antenna via a third coupling line extending in the second direction, and The second conductor layer of the first antenna is connected to the second conductor layer of the fifth antenna via a fourth coupling line extending in the second direction. The first coupling line and the third coupling line are connected at a position shifted from the center of the line segment connecting the first antenna and the second antenna.

2. An element comprising an antenna array in which a plurality of antennas are deployed, each antenna comprising: First conductor layer, A semiconductor layer, electrically connected to the first conductor layer, generates or detects terahertz waves. The second conductor layer is electrically connected to the semiconductor layer and is opposite to the first conductor layer across the semiconductor layer. A dielectric layer, located between the first conductor layer and the second conductor layer, and A bias line is used to connect the second conductor layer to a bias circuit for supplying a bias signal to the semiconductor layer, wherein... The antenna array includes a first antenna, a second antenna, a third antenna, a fourth antenna, and a fifth antenna. The second, first, and third antennas are arranged in this order along the first direction. The fourth, first, and fifth antennas are arranged in this order along a second direction intersecting the first direction. The second conductor layer of the second antenna is connected to the second conductor layer of the first antenna via a first coupling line extending in a first direction. The second conductor layer of the first antenna is connected to the second conductor layer of the third antenna via a second coupling line extending in the first direction. The second conductor layer of the fourth antenna is connected to the second conductor layer of the first antenna via a third coupling line extending in the second direction. The second conductor layer of the first antenna is connected to the second conductor layer of the fifth antenna via a fourth coupling line extending in the second direction, and The first coupling line and the bias line are deployed in different layers.

3. The element according to claim 1 or 2, wherein The first and second antennas are injected-locked to the frequency of terahertz waves via a first coupling line, and The first and fourth antennas are injected-locked to the frequency of terahertz waves via a third coupling line.

4. The element according to claim 1 or 2, wherein the first coupling line and the third coupling line are composed of a single conductor body.

5. The element according to claim 1 or 2, wherein the first coupling line and the third coupling line are connected at a position outside the node of the resonant electric field in the coupling line at the frequency of the terahertz wave.

6. The element according to claim 1 or 2, wherein the first coupling line and the third coupling line are connected at locations where they satisfy phase matching conditions with some adjacent antennas in the antenna at the frequency of the terahertz wave.

7. The element according to claim 1 or 2, wherein The third and fifth coupling lines, extending in the second direction, are deployed between the first and fourth antennas. The first and third coupling lines are connected at locations outside the nodes of the resonant electric field at the terahertz wave frequency; the first and fifth coupling lines are connected at locations outside the nodes of the resonant electric field at the terahertz wave frequency; and The nodes of the resonant electric field at the frequency of terahertz waves are located between the position where the first and third coupling lines are connected and the position where the first and fifth coupling lines are connected.

8. The element according to claim 1 or 2, wherein the first direction is the resonant direction of the resonant electric field at the frequency of a terahertz wave.

9. The element according to claim 1 or 2, wherein the second direction is orthogonal to the first direction.

10. The element according to claim 1 or 2, wherein the second direction is the direction of the magnetic field induced by the resonant electric field at the frequency of the terahertz wave.

11. The element according to claim 1 or 2, wherein each antenna radiates a circularly polarized wave.

12. The element according to claim 1 or 2, further comprising a bias line for connecting the second conductor layer to a bias circuit for supplying a bias signal to the semiconductor layer.

13. The element of claim 12, wherein the bias line is disposed in a layer between the first conductor layer and the second conductor layer.

14. The element according to claim 12, wherein The antenna array is deployed on the substrate. The first and third coupling lines are composed of a third conductor layer. The bias line consists of a fourth conductor layer, and The third and fourth conductor layers are deployed in layers different from the surface of the substrate.

15. The element of claim 14, wherein the substrate, the first conductor layer, the fourth conductor layer and the third conductor layer are laminated in this order.

16. The element of claim 14, wherein the substrate, the first conductor layer, the third conductor layer and the fourth conductor layer are laminated in this order.

17. The element according to claim 12, wherein, In frequency bands lower than terahertz waves, the bias line has a lower impedance than the semiconductor layer.

18. The element according to claim 1 or 2, wherein, In an antenna array, the antennas are arranged as an m-n matrix (m and n are integers, m≥2 and n≥2).

19. The element of claim 18, wherein the antennas of the antenna array are arranged at a spacing less than or equal to the wavelength of a terahertz wave.

20. The element according to claim 1 or 2, wherein the antenna is a patch antenna.

21. The element according to claim 1 or 2, wherein the semiconductor layer comprises a negative resistive element.

22. The element according to claim 21, wherein the negative resistive element is a resonant tunneling diode.

23. The element according to claim 1 or 2, wherein, in the case that the electrical length of each of the semiconductor layers of the first antenna and the second antenna is L1, L1 = 2π × k (k: an integer).

24. The element according to claim 1 or 2, wherein each antenna in the antenna comprises a second semiconductor layer that operates in opposite phase to the semiconductor layer.

25. An element comprising: An antenna array comprising multiple antennas, each antenna including a first conductive layer, a semiconductor layer electrically connected to the first conductive layer and generating or detecting terahertz waves, a second conductive layer electrically connected to the semiconductor layer and positioned opposite the first conductive layer via the semiconductor layer, and a dielectric layer located between the first and second conductive layers. The antenna array includes coupling lines, each connecting two adjacent antennas to transmit terahertz waves, and At least one antenna in the antenna array is connected to at least three or more coupling lines. The coupling lines extending in the first direction and the coupling lines extending in the second direction are connected at a position where the center of the antenna array between adjacent antennas in the first direction is shifted in the first direction.

26. The element of claim 25, wherein the three or more coupling lines are connected to the antenna at a connection portion.

27. The element of claim 25, wherein the three or more coupling lines are connected to the antenna at three or more different connection points.

28. The element of claim 25, wherein the three or more coupling lines are respectively connected to the antenna at separate connection points.

29. The element according to claim 25, wherein The first antenna is connected to at least two antennas via coupling lines, and The first antenna is connected to each of the at least two antennas via a single independent coupling line.

30. The element of claim 25, wherein two or more coupling lines are connected to each radiating end of at least one antenna in the antenna array.

31. The element of claim 25, wherein in a plan view, the at least three or more coupling lines are a single line inside the outer edge of the antenna, and the single line branches into two or more lines outside the outer edge.

32. The element of claim 25, wherein, in a plan view, the at least three or more coupling lines are arranged to be spaced apart from each other on the outer side of the outer edge of the antenna.

33. The element of claim 25, wherein the end of each coupling line is electrically terminated at the frequency of a terahertz wave.

34. The element of claim 25, wherein the antenna at the end of the antenna array does not have a coupling line on the outer edge side of the antenna array.

35. The element of claim 25, wherein the coupling line is connected to the antenna symmetrically about the centroid of the antenna.

36. An element comprising: An antenna array comprising multiple antennas, each antenna including a first conductive layer, a semiconductor layer electrically connected to the first conductive layer and generating or detecting terahertz waves, a second conductive layer electrically connected to the semiconductor layer and positioned opposite the first conductive layer across the semiconductor layer, a dielectric layer located between the first and second conductive layers, and a bias line for connecting the second conductive layer to a bias circuit for supplying a bias signal to the semiconductor layer. The antenna array includes coupling lines, each connecting two adjacent antennas to transmit terahertz waves, and At least one antenna in the antenna array is connected to at least three or more coupling lines in the coupling lines, and The first coupling line and the bias line are deployed in different layers.

37. A terahertz camera system, comprising: The transmitting section has the element according to any one of claims 1 to 36 and radiates terahertz waves; as well as The receiving section detects the terahertz wave.

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