A hybrid integrated schottky diode terahertz detector and preparation and detection method thereof

Abstract

The application provides a mixed integrated Schottky diode terahertz detector and a preparation and detection method thereof. The detector comprises a waveguide chip and a Schottky diode chip. The waveguide chip comprises a silicon-based dielectric waveguide and a metal antenna coupler. The metal antenna coupler comprises first and second metal coupling units that are electrically insulated from each other and form an antenna gap. The Schottky diode chip is flip-chip mounted on the waveguide chip and electrically connected to the two metal coupling units. A Schottky junction is arranged corresponding to the antenna gap. Terahertz guided modes are coupled to the antenna gap through the coupler, a terahertz voltage is formed between the metal coupling units, and a detection signal is generated through the Schottky junction rectification under the condition of no external direct current bias. The waveguide chip and the Schottky diode chip are prepared separately and mixed integrated through flip-chip micro-assembly. The application realizes local coupling and high-frequency feeding of terahertz guided modes and Schottky junctions, reduces additional high-frequency interconnections and the loss and parasitic effects introduced thereby.

Description

Technical Field

[0001] This invention relates to the field of terahertz detection and integrated device technology, specifically to a hybrid integrated Schottky diode terahertz detector and its fabrication and detection method. Background Technology

[0002] Terahertz technology has important applications in communication, imaging, spectral detection, and sensing. As terahertz systems develop towards miniaturization and integration, utilizing low-loss dielectric waveguides for on-chip transmission of terahertz signals, and further integrating terahertz functional devices on-chip, has become a crucial development direction for terahertz integration technology. High-resistivity silicon exhibits low dielectric loss and good micro / nano fabrication compatibility in the terahertz band, making it suitable for constructing silicon-based terahertz dielectric waveguides and integrated devices.

[0003] Schottky diodes, characterized by room-temperature operation, fast response, and compact structure, can be used for millimeter-wave and terahertz signal detection. Existing Schottky terahertz detectors typically employ free-space antennas, metallic waveguides, or planar transmission lines to couple and feed the terahertz signal to the Schottky junction region. For Schottky detectors integrated with silicon-based dielectric waveguides, further solutions are needed for electromagnetic energy coupling and high-frequency electrical connections between the guided mode of the dielectric waveguide and the Schottky junction. Additional transmission and interconnect structures may introduce additional transmission losses and parasitic effects.

[0004] Furthermore, the mode field scale of silicon-based terahertz dielectric waveguides is typically significantly larger than the micrometer or submicrometer junction scale of Schottky diodes. This substantial difference in spatial scale and mode field distribution makes it difficult for terahertz guided modes propagating in the waveguide to directly interact with the smaller Schottky junction region. Therefore, existing waveguide-integrated detection schemes still face challenges such as scale matching and local coupling between the dielectric waveguide guided modes and the Schottky junction, as well as losses and parasitic effects introduced by additional high-frequency interconnect structures. Summary of the Invention

[0005] The purpose of this invention is to provide a hybrid integrated Schottky diode terahertz detector and its fabrication and detection method, which realizes local coupling and high-frequency feeding between the terahertz guided mode and the Schottky junction in a silicon-based dielectric waveguide, and realizes terahertz signal detection without external DC bias.

[0006] The technical solution to achieve the purpose of this invention is: a hybrid integrated Schottky diode terahertz detector, comprising a waveguide chip and a Schottky diode chip, wherein:

[0007] The waveguide chip includes a silicon-based dielectric waveguide and a metal antenna coupler disposed on the upper surface of the silicon-based dielectric waveguide; the metal antenna coupler includes a first metal coupling unit and a second metal coupling unit that are spaced apart from each other and electrically insulated from each other, and an antenna gap is formed between their opposing ends;

[0008] The Schottky diode chip includes a Schottky junction and a first contact electrode and a second contact electrode electrically connected to both sides of the Schottky junction, respectively. The Schottky diode chip is flip-chip mounted on a waveguide chip with its active surface facing the metal antenna coupler. The first contact electrode is electrically connected to a first metal coupling unit, and the second contact electrode is electrically connected to a second metal coupling unit. The Schottky junction is correspondingly arranged with the antenna gap, so that the first metal coupling unit and the second metal coupling unit, while coupling terahertz guided mode energy to the antenna gap, feed terahertz signals to the Schottky junction through the first contact electrode and the second contact electrode, respectively, and form high-frequency feed terminals on both sides of the Schottky junction.

[0009] A metal antenna coupler is used to couple the terahertz guided mode energy transmitted in a silicon-based dielectric waveguide to the antenna gap, forming a terahertz voltage between the first metal coupling unit and the second metal coupling unit, and applying the terahertz voltage to the Schottky junction through the first contact electrode and the second contact electrode; the Schottky junction uses its nonlinear current-voltage characteristics to rectify the terahertz voltage and generate a rectified output.

[0010] Furthermore, the waveguide chip is formed by processing a high-resistivity silicon substrate, including a silicon substrate, a silicon-based dielectric waveguide located on the silicon substrate, and a first tapered coupling waveguide and a second tapered coupling waveguide disposed at both ends of the silicon-based dielectric waveguide; the silicon-based dielectric waveguide is a high-resistivity silicon ridge waveguide, and the first tapered coupling waveguide and the second tapered coupling waveguide are used to realize the input and output coupling of terahertz signals.

[0011] Furthermore, both the first metal coupling unit and the second metal coupling unit include a connecting pad and an antenna arm with tapered ends, the two tapered ends being arranged facing each other; the total length of the antenna arm is designed according to one-quarter of the equivalent wavelength of the working guided mode in the silicon-based dielectric waveguide at the target operating frequency; the first contact electrode and the second contact electrode are electrically connected to the corresponding connecting pads respectively.

[0012] Furthermore, the first and second metal coupling units are arranged opposite each other along the propagation direction of the silicon-based dielectric waveguide, the antenna arms are arranged along the propagation direction, and the antenna gap is located on the upper surface of the ridge of the silicon-based dielectric waveguide; the silicon-based dielectric waveguide adopts a quasi-transverse magnetic mode as the working guided mode, and the metal antenna coupler has polarization selectivity, is sensitive to the vertical electric field component of the quasi-transverse magnetic mode, and is not sensitive to the horizontal electric field component of the transverse electric mode, so as to effectively couple to the quasi-transverse magnetic mode.

[0013] Furthermore, the center of the Schottky junction is aligned with the center of the antenna gap, and the dimension of the Schottky junction in the antenna gap width direction is smaller than the width of the antenna gap.

[0014] Furthermore, the Schottky diode chip includes a semiconductor material layer, a Schottky anode, an ohmic contact electrode, a floating feed structure, a first contact electrode, and a second contact electrode; the Schottky anode forms a Schottky junction with the semiconductor material layer and is electrically connected to the first contact electrode through the floating feed structure; the ohmic contact electrode forms an ohmic contact with the semiconductor material layer and is electrically connected to the second contact electrode.

[0015] Furthermore, the Schottky diode chip is positioned across the first and second metal coupling units;

[0016] Along the direction of the two antenna arms, the size of the Schottky diode chip is larger than the total span of the two antenna arms and the antenna gap, and smaller than the corresponding size of the metal antenna coupler along that direction;

[0017] Along the direction perpendicular to the arrangement of the two antenna arms, the size of the Schottky diode chip is smaller than the corresponding size of the connection pad along that direction;

[0018] The first contact electrode and the second contact electrode are electrically connected to the first metal coupling unit and the second metal coupling unit respectively through conductive connecting materials, and the Schottky diode chip is fixed on the waveguide chip.

[0019] Furthermore, the semiconductor material layer is made of a semiconductor material that can form a Schottky barrier with the Schottky anode, and the material system can be selected according to the operating frequency band and high-frequency electrical characteristics of the detector.

[0020] Furthermore, the metal material of the metal antenna coupler can be selected based on its conductivity in the terahertz band and its compatibility with micro / nano fabrication.

[0021] Furthermore, the first contact electrode and the second contact electrode are electrically connected to the first metal coupling unit and the second metal coupling unit respectively via conductive connecting materials, and the Schottky diode chip is fixed on the waveguide chip. The conductive connecting material can be selected according to the electrical connection and device assembly requirements.

[0022] Furthermore, under conditions without external DC bias, the Schottky diode chip utilizes the nonlinear current-voltage characteristics of the Schottky junction to rectify the terahertz voltage applied across the Schottky junction, generating a DC signal or a low-frequency signal corresponding to the modulation envelope of the terahertz signal to be detected.

[0023] A method for fabricating the aforementioned hybrid integrated Schottky diode terahertz detector, comprising fabricating waveguide chips and Schottky diode chips separately, and hybrid integrating them via flip-chip microassembly, specifically including the following steps:

[0024] (a) Fabrication of waveguide chip: Micro-nano processing and metal patterning of silicon substrate to form silicon dielectric waveguide and metal antenna coupler disposed on the surface of silicon dielectric waveguide on silicon substrate. The metal antenna coupler includes a first metal coupling unit and a second metal coupling unit that are spaced apart from each other and electrically insulated from each other. An antenna gap is formed between the opposing ends of the first metal coupling unit and the second metal coupling unit.

[0025] (b) Fabrication of Schottky diode chip: Schottky junction, first contact electrode and second contact electrode are formed by semiconductor micro-nano fabrication process, and the first contact electrode and second contact electrode are electrically connected to the two sides of the Schottky junction respectively;

[0026] (c) Micro-assembly: The Schottky diode chip prepared in step (b) is flip-mounted onto the waveguide chip prepared in step (a) with the active surface facing the metal antenna coupler, so that the Schottky junction and the antenna gap are aligned, and the first contact electrode is electrically connected to the first metal coupling unit and the second contact electrode is electrically connected to the second metal coupling unit, thus fixing the Schottky diode chip onto the waveguide chip and completing the hybrid integration of the two.

[0027] A terahertz signal detection method based on the above-mentioned hybrid integrated Schottky diode terahertz detector includes: coupling the terahertz signal to be detected to a silicon-based dielectric waveguide, exciting a quasi-transverse magnetic mode in the silicon-based dielectric waveguide and propagating it along the silicon-based dielectric waveguide; using a metal antenna coupler to couple the terahertz guided mode energy propagating in the silicon-based dielectric waveguide to an antenna gap, forming a terahertz voltage between a first metal coupling unit and a second metal coupling unit, and applying the terahertz voltage to a Schottky junction through a first contact electrode and a second contact electrode; under conditions without external DC bias, rectifying the terahertz voltage using the nonlinear current-voltage characteristics of the Schottky junction to obtain a rectified DC signal or a low-frequency electrical signal corresponding to the modulation envelope of the terahertz signal to be detected.

[0028] Compared with the prior art, the significant advantages of this invention are:

[0029] 1) Achieve cross-scale local coupling between silicon-based dielectric waveguide guided modes and Schottky junction regions. Metallic antenna couplers selectively couple the quasi-transverse magnetic mode energy transmitted in silicon-based dielectric waveguides to the antenna gap, so that the local terahertz electric field acts on the smaller Schottky junction region, realizing local electromagnetic coupling from the silicon-based dielectric waveguide mode field scale to the Schottky junction scale.

[0030] 2) Reduce additional high-frequency interconnects and their introduced parasitic effects. The first and second metal coupling units, while realizing terahertz guided mode coupling, are electrically connected to the two contact electrodes of the Schottky diode chip, respectively, and form the high-frequency feed terminals on both sides of the Schottky junction. This allows the terahertz guided mode coupling and the high-frequency feed of the Schottky junction to be achieved by the same metal coupling structure, thereby helping to reduce additional high-frequency transmission and transition structures, as well as the interconnect losses and parasitic effects introduced therefrom.

[0031] 3) Achieve zero-bias terahertz detection. By utilizing the nonlinear current-voltage characteristics of the Schottky junction, the terahertz voltage can be rectified without an external DC bias, which simplifies the bias circuit and detection system structure.

[0032] 4) It has good process compatibility and integration. The waveguide chip and Schottky diode chip are fabricated separately and then integrated by flip-chip micro-assembly. They can be processed using the corresponding material systems, which helps to reduce the mutual constraints between different material systems and processing technologies, and facilitates further integration with other silicon-based terahertz functional devices. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a hybrid integrated Schottky diode terahertz detector.

[0034] Figure 2 This is a schematic diagram of the dimensions of a hybrid integrated Schottky diode terahertz detector.

[0035] Figure 3 This is a diagram showing the electric field distribution of a hybrid integrated Schottky diode terahertz detector.

[0036] Figure 4 The current-voltage characteristic curve of the hybrid integrated Schottky diode terahertz detector is shown.

[0037] Figure 5 The S-parameter results for the hybrid integrated Schottky diode terahertz detector are shown in the figure.

[0038] Figure 6 The external voltage response curve of the hybrid integrated Schottky diode terahertz detector.

[0039] Figure 7 The time-domain response curve of the hybrid integrated Schottky diode terahertz detector.

[0040] In the figure, 1 is a Schottky diode chip, 2 is a silicon-based dielectric waveguide, 3 is a metal antenna coupler, 4 is a first tapered coupling waveguide, 5 is a second tapered coupling waveguide, and 6 is a silicon substrate. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0042] like Figure 1 As shown, a hybrid integrated Schottky diode terahertz detector includes a waveguide chip and a Schottky diode chip 1. The waveguide chip includes a silicon-based dielectric waveguide 2, a metal antenna coupler 3, a first tapered coupling waveguide 4, a second tapered coupling waveguide 5, and a silicon substrate 6. The silicon-based dielectric waveguide 2 is disposed on the silicon substrate 6 and is used to transmit terahertz guided modes. The first tapered coupling waveguide 4 and the second tapered coupling waveguide 5 are respectively disposed at both ends of the silicon-based dielectric waveguide 2 to realize mode transition and terahertz signal coupling between the external metal rectangular waveguide and the silicon-based dielectric waveguide 2. The metal antenna coupler 3 is disposed on the upper surface of the silicon-based dielectric waveguide 2 and is used to couple the terahertz guided mode energy transmitted in the silicon-based dielectric waveguide 2 to the antenna gap. The Schottky diode chip 1 is flip-chip disposed on the waveguide chip with its active surface facing the metal antenna coupler 3 and is used to rectify and detect the terahertz voltage applied across the Schottky junction.

[0043] In this embodiment, the waveguide chip is formed using a high-resistivity silicon substrate. The silicon-based dielectric waveguide 2 adopts a ridge waveguide structure and is formed from the silicon substrate 6, the first tapered coupling waveguide 4, and the second tapered coupling waveguide 5 using a high-resistivity silicon substrate. The cross-sectional dimensions of the silicon-based dielectric waveguide 2, as well as the lengths, cone angles, and end dimensions of the first tapered coupling waveguide 4 and the second tapered coupling waveguide 5, can be designed according to the device's operating frequency band, waveguide transmission mode, and the mode field distribution of the external metal rectangular waveguide.

[0044] During device packaging, the first tapered coupling waveguide 4 and the second tapered coupling waveguide 5 are respectively placed within their respective metal rectangular waveguide channels to achieve input and output coupling between the terahertz signal and the silicon-based dielectric waveguide 2. The specifications of the metal rectangular waveguides can be selected according to the appropriate standard rectangular waveguide interface based on the device's operating frequency band.

[0045] In this embodiment, the silicon-based dielectric waveguide 2 employs a quasi-transverse magnetic mode as its operating mode. The metal antenna coupler 3 includes a first metal coupling unit and a second metal coupling unit that are spaced apart from each other and electrically insulated from each other. Both the first and second metal coupling units include a connecting pad and an antenna arm with tapered ends. The two tapered ends are arranged facing each other and form an antenna gap between them. The antenna gap is located on the upper surface of the ridge of the silicon-based dielectric waveguide 2.

[0046] The structure and arrangement of the metal antenna coupler 3 match the electric field distribution of the quasi-transverse magnetic working mode in the silicon-based dielectric waveguide 2, exhibiting polarization selectivity and enabling effective coupling of the quasi-transverse magnetic mode. When the quasi-transverse magnetic terahertz mode propagates to the region where the metal antenna coupler 3 is located, induced high-frequency currents and charge redistribution are generated on the first and second metal coupling units, causing the terahertz mode energy to couple to the antenna gap and forming a terahertz voltage between the first and second metal coupling units.

[0047] The structural dimensions of the metal antenna coupler 3 can be designed based on the operating frequency band, the mode field distribution of the silicon-based dielectric waveguide 2, and the size of the Schottky junction. The total length of the antenna arm is determined based on the equivalent wavelength of the working guided mode in the silicon-based dielectric waveguide 2 at the target operating frequency, using a quarter of the equivalent wavelength as the design basis. The antenna arm has a tapered end that gradually narrows towards the antenna gap. The geometry and dimensions of the tapered end can be optimized based on the target operating frequency and the local coupling characteristics at the antenna gap to improve the coupling efficiency of the terahertz guided mode to the antenna gap region. In this embodiment, the tapered end adopts a linear tapering structure. As the total length of the antenna arm increases, the local electric field enhancement peak shifts towards lower frequencies; under the same structural parameters, a smaller antenna gap results in stronger local coupling and a higher degree of electric field enhancement. The metal material of the metal antenna coupler 3 can be selected based on the conductivity of the terahertz band and its compatibility with micro / nano fabrication.

[0048] The Schottky diode chip 1 includes a semiconductor material layer, a Schottky anode, an ohmic contact electrode, a floating feed structure, a first contact electrode, and a second contact electrode. The Schottky anode forms a Schottky junction with the semiconductor material layer and is electrically connected to the first contact electrode through the floating feed structure; the ohmic contact electrode forms an ohmic contact with the semiconductor material layer and is electrically connected to the second contact electrode.

[0049] The semiconductor material system used in the Schottky diode chip 1 can be selected according to the device's operating frequency band and the high-frequency electrical characteristics of the Schottky junction. A semiconductor material system capable of forming a Schottky barrier suitable for the corresponding millimeter-wave or terahertz frequency band can be used. For the Schottky diode chip 1 using a semiconductor substrate, the semiconductor substrate can be thinned according to the device's high-frequency characteristics and assembly requirements to reduce the substrate's influence on the device's high-frequency characteristics.

[0050] The Schottky diode chip 1 is integrated with the waveguide chip using a flip-chip configuration and spans across the first and second metal coupling units. The dimension of the Schottky diode chip 1 along the relative orientation of the two metal coupling units is greater than the total span of the two antenna arms and the antenna gap, but less than the total span of the metal antenna coupler 3. Its width is less than the width of the connecting pads to meet the requirements of chip bridging, electrode connection, and flip-chip alignment. During assembly, the active surface of the Schottky diode chip 1 faces the metal antenna coupler 3, and the Schottky junction is positioned correspondingly to the antenna gap and aligned at the center. The dimension of the Schottky junction in the antenna gap width direction is smaller than the width of the antenna gap, so that the Schottky junction is located in the local strong electric field region of the antenna gap; for a circular Schottky anode, its diameter can be used to characterize the dimension of the Schottky junction in the antenna gap width direction. The first contact electrode and the second contact electrode are electrically connected to the first and second metal coupling units, respectively, so that the two metal coupling units respectively constitute the high-frequency feed terminals on both sides of the Schottky junction. The electrical connection can be achieved through a conductive connection material, and the Schottky diode chip 1 can be fixed to the waveguide chip through a conductive connection material or an independent fixing structure.

[0051] During operation, the terahertz signal to be detected is coupled to a silicon-based dielectric waveguide 2, exciting a quasi-transverse magnetic mode within the waveguide and propagating along it. When the terahertz guided mode propagates to the region where the metal antenna coupler 3 is located, its energy is coupled to the antenna gap, forming a terahertz voltage between the first and second metal coupling units. Since the first and second metal coupling units are electrically connected to the first and second contact electrodes of the Schottky diode chip 1, respectively, the terahertz voltage is applied across the Schottky junction through these electrodes. Without an external DC bias, the Schottky junction uses its nonlinear current-voltage characteristics to rectify the terahertz voltage, generating a DC signal or a low-frequency signal corresponding to the modulation envelope of the terahertz signal to be detected.

[0052] Furthermore, the waveguide chip and Schottky diode chip 1 in this invention are fabricated separately and then hybridized using a flip-chip micro-assembly method, specifically including the following steps:

[0053] (a) Fabrication of waveguide chip: A high-resistivity silicon substrate is selected. First, a metal antenna coupler 3 is formed on the upper surface of the high-resistivity silicon substrate through photolithography, metal deposition and lift-off processes. Then, the waveguide chip outline is formed by back-side overlay and back-side deep silicon etching. Finally, silicon-based dielectric waveguide 2, first tapered coupling waveguide 4 and second tapered coupling waveguide 5 are formed by front-side photolithography and deep silicon etching.

[0054] (b) Fabrication of Schottky diode chip: Schottky anode, ohmic contact electrode, floating feed structure, first contact electrode and second contact electrode are formed on semiconductor material layer by semiconductor micro-nano processing technology, so that Schottky anode forms Schottky junction with semiconductor material layer and ohmic contact electrode forms ohmic contact with semiconductor material layer; for Schottky diode chip using semiconductor substrate, the semiconductor substrate is thinned according to device design requirements and the Schottky diode chip 1 is separated.

[0055] (c) Micro-assembly: The Schottky diode chip 1 is flip-chip mounted on the waveguide chip with the active surface facing the metal antenna coupler 3. The Schottky junction is aligned with the antenna gap by microscopic alignment, and the first contact electrode is aligned with the first metal coupling unit and the second contact electrode is aligned with the second metal coupling unit. The first contact electrode is electrically connected to the first metal coupling unit and the second contact electrode is electrically connected to the second metal coupling unit by conductive connecting material. The Schottky diode chip 1 is then fixed on the waveguide chip, completing the hybrid integration of the Schottky diode chip 1 and the waveguide chip.

[0056] Example

[0057] This embodiment uses a hybrid integrated Schottky diode terahertz detector with a WR-2.2 standard rectangular waveguide interface as an example to illustrate the specific structural parameters and terahertz detection performance of the present invention.

[0058] like Figure 2 As shown, in this embodiment, a high-resistivity silicon substrate with a thickness of 200 μm and a resistivity of approximately 10 kΩ·cm is used to fabricate the waveguide chip. The silicon-based dielectric waveguide 2 adopts a ridge waveguide structure, with a straight waveguide section length l1 of 4000 μm, a ridge width w1 of 150 μm, a ridge height of 150 μm, and a silicon layer thickness of 50 μm below the ridge. The first tapered coupling waveguide 4 and the second tapered coupling waveguide 5 adopt the same structure, with a tapered transition length l2 of 625 μm and a corresponding apex angle of approximately 9.1°.

[0059] A metallic antenna coupler 3 is disposed on the upper surface of the ridge of the silicon-based dielectric waveguide 2. The first and second metallic coupling units adopt the same structure, with both the length l3 and width w3 of the connecting pads being 120 μm. The total length of the antenna arm is designed based on one-quarter of the equivalent wavelength of the working guided mode and optimized using full-wave electromagnetic simulation. The equal-width portion has a length l4 of 50 μm and a width w2 of 12 μm, while the tapered end adopts a linear tapered structure with a length l5 of 10 μm. A 6 μm antenna gap is formed between the two tapered ends. The metallic antenna coupler 3 is made of gold with a gold layer thickness of 100 nm.

[0060] This embodiment uses an indium gallium arsenide (IGaAs) Schottky diode chip 1 on an indium phosphide substrate, with a chip size of 200 μm × 50 μm. Along the relative arrangement direction of the two metal coupling units, the total span of the two antenna arms and the antenna gap is 126 μm, and the total span of the metal antenna coupler 3 is 366 μm. The chip size along this direction is 200 μm, meeting the size requirement of the chip spanning two metal coupling units. Simultaneously, the chip width is 50 μm, smaller than the 120 μm width of the connection pad, thus meeting the size requirements for chip bridging, flip-chip alignment, and electrode connection. The Schottky anode radius is 0.2 μm. For a circular Schottky anode, its size in the antenna gap width direction is characterized by its diameter; therefore, the size of the Schottky junction in the antenna gap width direction is 0.4 μm, smaller than the 6 μm antenna gap width. The Schottky anode and ohmic contact electrodes adopt a titanium / gold laminated metal structure. The indium phosphide substrate is thinned to 100 μm. The waveguide chip and Schottky diode chip 1 were fabricated according to the above method. The Schottky diode chip 1 was flip-chip mounted on the waveguide chip with its active surface facing the metal antenna coupler 3. Microscopic alignment was used to ensure the Schottky junction and antenna gap were aligned, and their centers were aligned. As one embodiment of the conductive connection material, conductive silver paste was used to electrically connect the first contact electrode to the first metal coupling unit and the second contact electrode to the second metal coupling unit, simultaneously achieving mechanical fixation between the Schottky diode chip 1 and the waveguide chip. After micro-assembly, the device was mounted in a metal package structure with a standard WR-2.2 interface.

[0061] To verify the coupling effect of the metal antenna coupler 3 on the transverse magnetic mode terahertz guided mode, a full-wave electromagnetic simulation was performed on the above structure. For example... Figure 3 As shown, the square of the electric field strength |E| 2 The formation of a significant local enhancement near the antenna gap indicates that the metal antenna coupler 3 can couple part of the terahertz guided mode energy in the silicon-based dielectric waveguide 2 to the antenna gap and form a local strong electric field in the antenna gap region.

[0062] To verify the nonlinear electrical characteristics of Schottky diode chip 1, its DC volt-ampere characteristics were tested. For example... Figure 4 As shown, under forward bias, the current of Schottky diode chip 1 increases nonlinearly with the applied voltage, while under reverse bias, the current remains at a low level, exhibiting obvious asymmetric current-voltage characteristics and rectification characteristics.

[0063] To verify the terahertz transmission characteristics of the device, the packaged device was connected to a terahertz vector network analysis system, and its transmission parameter S was measured. 21 and reflection parameter S 11 .like Figure 5As shown, the device S was obtained in the frequency range of 350–450 GHz. 21 and S 11 The frequency-dependent response indicates that the terahertz signal can be coupled into the waveguide chip and transmitted through the packaged device, while also reflecting the combined electromagnetic response after loading the metal antenna coupler 3 and the Schottky diode chip 1.

[0064] To verify the zero-bias terahertz detection performance of the detector, the rectified response voltage generated by Schottky diode chip 1 was measured under conditions without external DC bias. External voltage responsivity R v Defined as: R v = V resp / P in , where V resp P is the rectified response voltage. in This is for calibrating the terahertz input power to the input facet of the device package. For example... Figure 6 As shown, zero-bias rectified response can be obtained in the frequency range of 350–450 GHz, with an average external voltage responsivity of approximately 67 V / W, indicating that the detector can achieve zero-bias terahertz detection in the frequency range of 350–450 GHz. Combined with… Figure 3 The antenna gap local field enhancement and Figure 5 The transmission and loading responses of the packaged device shown further demonstrate that terahertz guided mode energy can act on the Schottky junction via the metal antenna coupler 3 and participate in rectification and detection.

[0065] To verify the detector's dynamic response capability, a square-wave modulated continuous terahertz signal was used for testing. For example... Figure 7 As shown, at a modulation frequency of 1 MHz, the detector output voltage can change accordingly with the periodic switching of the incident terahertz signal, indicating that the detector can achieve zero-biased terahertz dynamic detection at the megahertz level.

[0066] In summary, the hybrid integrated Schottky diode terahertz detector of this embodiment can couple the quasi-transverse magnetic terahertz guided mode energy transmitted in the silicon-based dielectric waveguide 2 to the antenna gap of the metal antenna coupler 3, and apply the terahertz voltage formed between the two metal coupling units to the Schottky junction through the first contact electrode and the second contact electrode, which are electrically connected to the two metal coupling units respectively, thereby realizing the rectification and detection of terahertz signals without external DC bias.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A hybrid integrated Schottky diode terahertz detector, characterized in that, Includes waveguide chips and Schottky diode chips (1), wherein: The waveguide chip includes a silicon-based dielectric waveguide (2) and a metal antenna coupler (3) disposed on the upper surface of the silicon-based dielectric waveguide (2). The metal antenna coupler (3) includes a first metal coupling unit and a second metal coupling unit that are spaced apart from each other and electrically insulated from each other. An antenna gap is formed between the opposing ends of the first metal coupling unit and the second metal coupling unit. The Schottky diode chip (1) includes a Schottky junction and a first contact electrode and a second contact electrode that are electrically connected to both sides of the Schottky junction, respectively; The Schottky diode chip (1) is flip-chip mounted on the waveguide chip with its active surface facing the metal antenna coupler (3). The first contact electrode is electrically connected to the first metal coupling unit, and the second contact electrode is electrically connected to the second metal coupling unit. The Schottky junction is correspondingly arranged with the antenna gap, so that the first metal coupling unit and the second metal coupling unit can couple the terahertz guided mode energy to the antenna gap, and feed the terahertz signal to the Schottky junction through the first contact electrode and the second contact electrode respectively, and form the high-frequency feed terminals on both sides of the Schottky junction. The metal antenna coupler (3) is used to couple the terahertz guided mode energy transmitted in the silicon-based dielectric waveguide (2) to the antenna gap, forming a terahertz voltage between the first metal coupling unit and the second metal coupling unit, and applying the terahertz voltage to the Schottky junction through the first contact electrode and the second contact electrode; the Schottky junction uses its nonlinear current-voltage characteristics to rectify the terahertz voltage and generate a rectified output.

2. The hybrid integrated Schottky diode terahertz detector according to claim 1, characterized in that, The waveguide chip is formed by processing a high-resistivity silicon substrate and includes a silicon substrate (6), a silicon-based dielectric waveguide (2) located on the silicon substrate (6), and a first tapered coupling waveguide (4) and a second tapered coupling waveguide (5) disposed at both ends of the silicon-based dielectric waveguide (2); the silicon-based dielectric waveguide (2) is a high-resistivity silicon ridge waveguide, and the first tapered coupling waveguide (4) and the second tapered coupling waveguide (5) are used for input and output coupling of terahertz signals.

3. The hybrid integrated Schottky diode terahertz detector according to claim 1, characterized in that, Both the first metal coupling unit and the second metal coupling unit include a connecting pad and an antenna arm with tapered ends, with the two tapered ends facing each other; the total length of the antenna arm is designed according to one-quarter of the equivalent wavelength of the working guided mode in the silicon-based dielectric waveguide (2) at the target operating frequency; the first contact electrode and the second contact electrode are electrically connected to the corresponding connecting pads respectively.

4. The hybrid integrated Schottky diode terahertz detector according to claim 3, characterized in that, The first metal coupling unit and the second metal coupling unit are arranged opposite each other along the propagation direction of the silicon-based dielectric waveguide (2), the antenna arm is arranged along the propagation direction, and the antenna gap is located on the upper surface of the ridge of the silicon-based dielectric waveguide (2); the silicon-based dielectric waveguide (2) adopts the quasi-transverse magnetic mode as the working mode, and the metal antenna coupler (3) has polarization selectivity, is sensitive to the vertical electric field component of the quasi-transverse magnetic mode, and is not sensitive to the horizontal electric field component of the transverse electric mode, so as to effectively couple the quasi-transverse magnetic mode.

5. The hybrid integrated Schottky diode terahertz detector according to claim 1, characterized in that, The center of the Schottky junction is aligned with the center of the antenna gap, and the dimension of the Schottky junction in the width direction of the antenna gap is smaller than the width of the antenna gap.

6. The hybrid integrated Schottky diode terahertz detector according to claim 1, characterized in that, The Schottky diode chip (1) includes a semiconductor material layer, a Schottky anode, an ohmic contact electrode, a floating feed structure, a first contact electrode, and a second contact electrode. The Schottky anode forms a Schottky junction with the semiconductor material layer and is electrically connected to the first contact electrode through the floating feed structure. The ohmic contact electrode forms an ohmic contact with the semiconductor material layer and is electrically connected to the second contact electrode.

7. The hybrid integrated Schottky diode terahertz detector according to claim 3, characterized in that, The Schottky diode chip (1) is positioned across the first metal coupling unit and the second metal coupling unit; Along the direction of the two antenna arms, the size of the Schottky diode chip (1) is greater than the total span of the two antenna arms and the antenna gap, and smaller than the corresponding size of the metal antenna coupler (3) along that direction; Along the direction perpendicular to the arrangement of the two antenna arms, the size of the Schottky diode chip (1) is smaller than the corresponding size of the connecting pad along that direction; The first contact electrode and the second contact electrode are electrically connected to the first metal coupling unit and the second metal coupling unit respectively through conductive connecting materials, and the Schottky diode chip (1) is fixed on the waveguide chip.

8. The hybrid integrated Schottky diode terahertz detector according to claim 1, characterized in that, Without external DC bias, the Schottky diode chip (1) uses the nonlinear current-voltage characteristic of the Schottky junction to rectify the terahertz voltage applied to both sides of the Schottky junction, generating a DC signal or a low-frequency signal corresponding to the modulation envelope of the terahertz signal to be detected.

9. A method for fabricating the hybrid integrated Schottky diode terahertz detector of claim 1, characterized in that, Waveguide chips and Schottky diode chips are fabricated separately and then hybridized using a flip-chip microassembly method, including the following steps: (a) Fabrication of waveguide chip: Micro-nano processing and metal patterning of silicon substrate to form silicon dielectric waveguide (2) and metal antenna coupler (3) disposed on the upper surface of silicon dielectric waveguide (2) on silicon substrate. The metal antenna coupler (3) includes a first metal coupling unit and a second metal coupling unit that are spaced apart from each other and electrically insulated from each other. An antenna gap is formed between the opposing ends of the first metal coupling unit and the second metal coupling unit. (b) Fabrication of Schottky diode chip: Schottky junction, first contact electrode and second contact electrode are formed by semiconductor micro-nano fabrication process, and the first contact electrode and the second contact electrode are electrically connected to the two sides of the Schottky junction respectively; (c) Micro-assembly: The Schottky diode chip (1) prepared in step (b) is flip-mounted onto the waveguide chip prepared in step (a) with the active surface facing the metal antenna coupler (3), so that the Schottky junction and the antenna gap are correspondingly set, the first contact electrode is electrically connected to the first metal coupling unit, the second contact electrode is electrically connected to the second metal coupling unit, and the Schottky diode chip (1) is fixed on the waveguide chip to complete the hybrid integration of the Schottky diode chip (1) and the waveguide chip.

10. A method for detecting terahertz signals based on the hybrid integrated Schottky diode terahertz detector of claim 1, characterized in that, Includes the following steps: The terahertz signal to be detected is coupled to a silicon-based dielectric waveguide (2), and a quasi-transverse magnetic permeability mode is excited in the silicon-based dielectric waveguide (2) and propagates along the silicon-based dielectric waveguide (2); The terahertz guided mode energy transmitted in the silicon-based dielectric waveguide (2) is coupled to the antenna gap using a metal antenna coupler (3), forming a terahertz voltage between the first metal coupling unit and the second metal coupling unit, and the terahertz voltage is applied to the Schottky junction through the first contact electrode and the second contact electrode. Without external DC bias, the nonlinear current-voltage characteristic of the Schottky junction is used to rectify the terahertz voltage, and the rectified DC signal or a low-frequency signal corresponding to the modulation envelope of the terahertz signal to be detected is obtained.

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