Tunneling structure and photonic device

Abstract

The invention belongs to the technical field of quantum tunneling, and provides a tunneling structure and a photonic device.The tunneling structure comprises an antenna layer, a first conductive layer, an insulating layer, a second conductive layer and a substrate layer, and the antenna layer, the first conductive layer, the insulating layer, the second conductive layer and the substrate layer are sequentially stacked in the first direction; the antenna layer comprises one or more antenna units stacked on the first conductive layer; the first conductive layer and / or the second conductive layer are / is provided with at least one hole structure, and in the first direction, the projection of each antenna unit on the first conductive layer or the second conductive layer spans and covers the two sides of an orifice contour line of the hole structure. The invention aims to solve the technical problem that the external quantum efficiency is reduced due to destructive interference caused by symmetrical excitation of a tunneling structure in the prior art, and prevents metal bulges from being introduced on a nano antenna and playing a role of a tunneling metal layer at the same time.

Description

Technical Field

[0001] The present application belongs to the field of quantum tunneling technology, and in particular relates to a tunneling structure and a photonic device. Background Art

[0002] Inelastic electron tunneling is a quantum tunneling excitation mechanism that uses low-energy electrons to excite metal surface plasmons and photon emission.

[0003] When inelastic tunneling junctions are used in actual light sources, the proportion of inelastic tunneling electrons is extremely low, and there is a wave vector mismatch problem between near-field plasmons and far-field photon radiation, resulting in extremely low final photon radiation efficiency of the tunneling junction. In recent years, people have found that the internal quantum efficiency and photon radiation efficiency in tunneling junctions can be increased by increasing the local density of optical states (LDOS). And one team has increased the electron-to-photon conversion efficiency to the order of 2% by designing local hotspots introduced by surface plasmon resonance. However, there are still many challenges to truly push tunneling junction light sources to the same status as LEDs and nanolasers: a. Tunneling junctions need to be made with the help of micro-nano manipulation technology or special chemical synthesis processes, which cannot be produced reliably and stably; b. Nanostructures made using compatible processes cannot avoid coherent superposition between multiple modes. Summary of the invention

[0004] The purpose of the present application is to provide a tunneling structure and a photonic device, in particular, an asymmetric electrically excited tunneling structure and a photonic device, which aims to solve the problem of reduced quantum efficiency caused by destructive interference due to the symmetrical excitation of the tunneling structure in the prior art, and avoid the introduction of metal protrusions on the nanoantenna that simultaneously play the role of a tunneling metal layer.

[0005] The first object of the present application is to provide a tunneling structure, including an antenna layer, a first conductive layer, an insulating layer, a second conductive layer and a substrate layer, wherein the antenna layer, the first conductive layer, the insulating layer, the second conductive layer and the substrate layer are stacked in sequence along a first direction; the antenna layer includes one or more antenna units stacked on the first conductive layer; at least one hole structure is opened on the first conductive layer and / or the second conductive layer, and along the first direction, the projection of each antenna unit on the first conductive layer or the second conductive layer covers both sides of the hole mouth contour line of the hole structure.

[0006] In one of the embodiments, when the antenna layer includes a plurality of antenna units, the plurality of antenna units are arranged in an array on the surface of the first conductive layer.

[0007] In one of the embodiments, the antenna layer includes a plurality of the antenna units; the hole opening of the hole structure is rectangular, and the hole opening has two wall edges arranged opposite to each other, and along the first direction, a projection of at least one of the antenna units is projected onto each of the two wall edges.

[0008] In one of the embodiments, a projection of the antenna unit projected onto one of the wall edges and a projection of the antenna unit projected onto another of the wall edges are symmetrically arranged about a midline of the aperture.

[0009] In one of the embodiments, projections of the two antenna units are respectively projected onto the two wall edges.

[0010] In one embodiment, the areas of the antenna units on both sides of the corresponding wall edge are equal.

[0011] In one embodiment, the shape of each of the antenna units includes a rod-shaped, elliptical sheet-shaped, butterfly-shaped and tooth-shaped; when the antenna layer includes multiple antenna units, the shapes of the multiple antenna units include a combination of one or more of the rod-shaped, elliptical sheet-shaped, butterfly-shaped and tooth-shaped.

[0012] In one embodiment, the antenna layer is an antenna layer made of gold material, silver material, copper material or other alloy material, or a combination of one or more of gold material, silver material and copper material; and / or

[0013] The substrate layer is a substrate layer made of SOI, Si, SiC, polydimethylsiloxane or glass; and / or

[0014] The first conductive layer and the second conductive layer are both conductive layers made of two-dimensional conductive materials; and / or

[0015] The insulating layer is an insulating material that is a combination of one or more of hexagonal boron nitride, Al2O3 and SiO2.

[0016] In one embodiment, the two-dimensional conductive material includes a single layer or multiple layers of graphene, molybdenum sulfide or a combination of one or more other two-dimensional conductive materials.

[0017] In one embodiment, the tunneling structure further includes a dielectric layer, and the dielectric layer is located between the antenna layer and the first conductive layer; the dielectric layer is a dielectric layer made of a combination of one or more of SiO2, Si3N4, Si, Al2O3, Air and hexagonal boron nitride.

[0018] In one of the embodiments, the antenna layer is connected to the first conductive layer via an adhesive layer; the adhesive layer is a metal adhesive layer that is a combination of one or more of Ti, Cr, and Pd and is adhesive and conductive.

[0019] In one embodiment, the thickness of the antenna layer is 20nm-60nm; and / or

[0020] The thickness of the adhesion layer is 1 nm-5 nm; and / or

[0021] The thickness of the insulating layer is 1nm-3nm.

[0022] A second object of the present application is to provide a photonic device, comprising a tunneling structure as described in any one of the above items.

[0023] The tunneling structure and photonic device of the present application have the following beneficial effects relative to the prior art: Compared with the prior art, in the tunneling structure and photonic device, when the antenna layer is placed on the outside of the first conductive layer in the basic tunnel structure, the different excitations of the plasma mode in the nanoantenna increase the probability of inelastic tunneling of electrons in the tunneling junction. The asymmetric excitation structure of the nanoantenna can avoid the reduction of quantum efficiency caused by destructive interference, and avoids the introduction of metal protrusions on the nanoantenna and playing the role of the tunneling metal layer at the same time, thereby improving the conversion efficiency of electrons to plasmons, and plasmons to photons. The combination of plasmons and tunneling electrons increases the photocurrent passing through the tunneling junction, making the detection of photons possible. The tunneling junction in this embodiment is a new tunneling structure that includes an antenna, and adopts a vertical stacking method, which is more conducive to the tunneling of electrons. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of the structure of a tunneling structure provided in an embodiment of the present application in the xz plane. Figure 1 ;

[0026] Figure 2 yes Figure 1 Schematic diagram of the electron tunneling process when the tunnel junction in FIG.

[0027] Figure 3 is a simplified energy level diagram of a tunneling structure under a bias voltage provided in an embodiment of the present application;

[0028] Figure 4 This is a schematic diagram of the structure of a tunneling structure provided in an embodiment of the present application in the xz plane. Figure 2 ;

[0029] Figure 5 is a schematic structural diagram of a tunneling structure on the upper surface (xy plane) provided in an embodiment of the present application;

[0030] Figure 6 Schematic diagram of an array structure of antenna units in a tunnel structure provided in an embodiment of the present application Figure 1 ;

[0031] Figure 7 Schematic diagram of an array structure of antenna units in a tunnel structure provided in an embodiment of the present application Figure 2 ;

[0032] Figure 8 Schematic diagram of an array structure of antenna units in a tunnel structure provided in an embodiment of the present application Figure 3 ;

[0033] Fig. 9 is a curve showing the change of normalized local optical state density of a tunnel junction with wavelength provided in an embodiment of the present application;

[0034] Fig.10 is the photon radiation efficiency P of a tunnel junction provided in the embodiment of the present application rad / P tot Curves that vary with wavelength;

[0035] Fig.11 is the normalized photon radiation power P of a tunnel junction provided in an embodiment of the present application rad / P0 curve changing with wavelength.

[0036] Explanation of the reference numerals: 1. antenna layer; 11. antenna unit; 2. first conductive layer; 21. hole structure; 22. hole wall; 3. insulating layer; 4. second conductive layer; 5. substrate layer; 6. dielectric layer. DETAILED DESCRIPTION

[0037] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0038] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "upward", "vertical", "horizontal", "bottom", "inside", "outside", "inner side", "outer side" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0039] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] Tunneling is a concept in quantum mechanics, which means that an electron can have a certain probability of passing through a potential barrier greater than its kinetic energy. A tunneling junction is a light source with an internal quantum tunneling effect based on a three-layer structure of conductor-insulator-conductor or conductor-insulator-semiconductor. When the conductor is made of metal (M) or semiconductor (S), a MIM or MIS structure can be formed. Compared with traditional light sources, tunneling light sources have the advantages of high operating speed, low power consumption, and ultra-small size.

[0042] The original structure of the tunneling light source is the MIM structure, that is, a first metal layer (M), an insulating layer (I) and a second metal layer (M) are sequentially provided on the surface of a substrate layer (referred to as the substrate). Its working mode and principle are: when a bias relative to the first metal layer is applied to the second metal layer; since the insulating layer is very thin (equivalent to the mean free path of electrons), the electrons in the first metal layer will undergo quantum tunneling effect through the insulating layer and enter the second metal layer. In the process of tunneling through the insulating layer, the energy of the electrons is transferred to the surface plasmons or radiated out in the form of photons.

[0043] In the tunneling light source of the MIM structure, electrons tunnel through the insulating layer in elastic and inelastic ways, but only a small proportion of inelastic tunneling electrons can generate surface plasmons and photon radiation; in addition, the plasmons on the metal surface have a wave vector mismatch with the free space, resulting in only a small part of the surface plasmons in the traditional tunneling junction being converted into photons, so the quantum efficiency (ratio of radiation power to input power) is very low. In addition, the destructive interference of multiple modes of the nanoantenna will also reduce the quantum efficiency of the tunneling junction.

[0044] Therefore, it can be seen that the main bottleneck of the application of inelastic tunneling junctions in practical light sources in related technologies lies in the extremely low proportion of inelastic tunneling electrons, the wave vector mismatch between near-field plasmons and far-field photon radiation, and the multi-mode destructive interference in the tunneling junction, which results in the final photon radiation efficiency of the tunneling junction being only 10 -5 -10 -4 .

[0045] Therefore, how to improve the radiation efficiency of photons is a technical problem that needs to be solved in this application.

[0046] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0047] See also Figure 1 and Figure 2 and Figure 3 As shown, an embodiment of the present application provides a tunneling structure, which can also be called a tunneling junction. The tunneling structure includes an antenna layer 1, a first conductive layer 2, an insulating layer 3, a second conductive layer 4 and a substrate layer 5. The antenna layer 1, the first conductive layer 2, the insulating layer 3, the second conductive layer 4 and the substrate layer 5 are stacked in sequence along a first direction; the antenna layer 1 includes one or more antenna units 11 stacked on the first conductive layer 2; at least one hole structure 21 is opened on the first conductive layer 2 and / or the second conductive layer 4, and along the first direction, the projection of each antenna unit 11 on the first conductive layer 2 or the second conductive layer 4 covers (or straddles) both sides of the hole mouth contour line (cross-sectional contour line of the hole wall 22) of the hole structure 21.

[0048] Specifically, refer to Figure 1 As shown, the first direction may refer to the vertical direction, Figure 1 It is a schematic diagram of the structure of the tunneling structure in the xz plane (or vertical plane), in which the first conductive layer 2, the insulating layer 3, and the second conductive layer 4 are stacked in the vertical direction, and the first conductive layer 2, the insulating layer 3 and the second conductive layer 4 form a basic tunneling structure.

[0049] Analyzing the working principle of the basic tunneling structure, inelastic electron tunneling is a quantum tunneling excitation mechanism that uses low-energy electrons to excite metal surface plasmons and photon emission. Different from the slower recombination rate of electron-hole pairs in LEDs and the larger size restrictions in lasers, the electrons in the quantum tunneling junction complete the energy transfer during the inelastic tunneling process. It is essentially a plasmon luminescence mechanism that can break through the optical diffraction limit and does not require the participation of other processes. The electron tunneling rate is in the femtosecond order. The quantum tunneling junction allows electrons to tunnel inelastically from one electrode through a nanoscale oxide barrier layer to the other electrode, accompanied by the collective resonance excitation of free electrons on the metal surface and photon radiation.

[0050] Among them, for plasmons, surface plasmons are electromagnetic oscillations that excite and couple charge density fluctuations at the interface of a conductive layer (such as metal) and a medium, and have the characteristics of near-field enhancement, surface confinement, and short wavelength. The Coulomb interaction between electrons in metals is a long-range interaction, and the fluctuation of electron density will cause the collective motion of the entire electronic system. The oscillation of the free electron gas relative to the uniform positive background is called plasma oscillation. Plasmons are quantized plasma oscillation energy quanta and are body-excited wave-color type quasiparticles.

[0051] The above-mentioned almost unlimited response time and extremely small size that breaks the optical diffraction limit provide a new possibility for realizing an ultra-fast, ultra-compact and CMOS-compatible on-chip integrated light source, and enable it to be used for data transmission, optical computing and biosensing, etc.; among them, CMOS is the abbreviation of Complementary Metal-Oxide-Semiconductor, and its Chinese name is complementary metal oxide semiconductor, which is a description of silicon-based semiconductor technology.

[0052] Research on the application of nanoantennas in quantum tunneling junctions has found that the external quantum efficiency of quantum tunneling junctions can be significantly enhanced by designing high-quality optical nanoantennas. The localized surface plasmon resonance on the nanoantenna tunneling junction will directly increase the probability of electron inelastic tunneling, that is, improve the conversion efficiency of electrons to plasmons.

[0053] Therefore, in this embodiment, the antenna layer 1 is placed on the side of the first conductive layer 2 facing away from the insulating layer 3 , and the antenna layer 1 may be a nano-antenna.

[0054] The setting of the antenna layer 1 has a significant enhancing effect on the inelastic tunneling probability of electrons. Specifically, after applying a bias voltage to the first conductive layer 2 and the second conductive layer 4 of the tunneling junction, the electrons tunnel and generate photons that are transmitted to the surface of the antenna layer 1, so that the surface of the antenna layer 1 can emit localized plasmons. Surface plasmons are electromagnetic oscillations that excite and couple charge density fluctuations at the metal-dielectric interface, and have the characteristics of near-field enhancement, surface confinement, and short wavelength. Localized plasmons can enhance electron tunneling.

[0055] Furthermore, the antenna layer 1 includes one or more antenna units 11 stacked on the first conductive layer 2, and the antenna unit 11 may adopt a nano-antenna structure; at least one hole structure 21 is opened on the first conductive layer 2 and / or the second conductive layer 4, and along the first direction, the projection of each antenna unit 11 on the first conductive layer 2 or the second conductive layer 4 covers both sides of the hole mouth contour line of the hole structure 21 or covers the hole mouth contour line of the hole structure 21, or it can be said that along the first direction, the projection of each antenna unit 11 on the first conductive layer 2 or the second conductive layer 4 covers the cross-sectional contour line of the hole wall 22 of the hole structure 21, or straddles or covers both sides of the single-sided line body of the cross-sectional contour line of the hole wall 22 of the hole structure 21.

[0056] Specifically, the antenna layer 1 may include an antenna unit 11 , and the antenna unit 11 adopts a nano-antenna structure; the antenna layer 1 may also include a plurality of antenna units 11 , and the plurality of antenna units 11 are arranged on the surface of the first conductive layer 2 .

[0057] At least one hole structure 21 is provided on the first conductive layer 2 and / or the second conductive layer 4, which means that at least one hole structure 21 is provided on the first conductive layer 2; or at least one hole structure 21 is provided on the second conductive layer 4; or at least one hole structure 21 is provided on the first conductive layer 2 and at least one hole structure 21 is provided on the second conductive layer 4.

[0058] Along the first direction, the projection of each antenna unit 11 on the first conductive layer 2 or the second conductive layer 4 spans or covers both sides of the hole mouth contour line of the hole structure 21, which means that when a hole structure 21 is provided on the first conductive layer 2, the projection of each antenna unit 11 on the first conductive layer 2 covers both sides of the cross-sectional contour line of the hole wall 22 of the hole structure 21; or when a hole structure 21 is provided on the second conductive layer 4, the projection of each antenna unit 11 on the second conductive layer 4 covers both sides of the cross-sectional contour line of the hole wall 22 of the hole structure 21; or when the hole structure 21 is provided on both the first conductive layer 2 and the second conductive layer 4, the projection of each antenna unit 11 on the first conductive layer 2 can cover both sides of the cross-sectional contour line of the hole wall 22 of the hole structure 21, or the projection of each antenna unit 11 on the second conductive layer 4 can cover both sides of the cross-sectional contour line of the hole wall 22 of the hole structure 21.

[0059] Among them, the projection of the antenna unit 11 on the conductive layer (referring to the first conductive layer 2 or the second conductive layer 4) covers both sides of the hole mouth contour line of the hole structure 21, which means that the antenna unit 11 is projected toward the conductive layer along the first direction, and a part of the projected projection is in the hole mouth space of the hole structure 21, and the other part is on the solid surface of the conductive layer. The line body of the hole mouth contour line (or the hole wall 22) is located in the middle area of ​​the projection. It can also be said that the line body of the hole mouth contour line (or the hole wall 22) divides the projection into two. It can also be said that the projection covers both sides of the wall edge of the hole mouth (or the wall edge line or the contour line body), and the wall edge of the hole mouth is also the hole wall 22 of the hole structure 21. Therefore, in the following, the wall edge of the hole mouth (or the contour line of the hole mouth) is equivalent to the hole wall 22 of the hole structure 21 or the cross-sectional contour line of the hole wall 22.

[0060] The hole shape of the hole structure 21 can be circular, elliptical, polygonal or other regular or irregular closed loop shapes; in addition, the hole structure 21 can be formed by etching.

[0061] The above-mentioned design of the antenna unit 11 enables the antenna unit 11 to form a misalignment and asymmetry with the surface of the first conductive layer 2 or the second conductive layer 4, so that a part of the surface of the antenna unit 11 is in contact with the surface of the first conductive layer 2 and the second conductive layer 4, and another part of the surface is located in the space of the hole structure 21. Another part of the surface of the antenna unit 11 can be directly connected to the insulating layer 3 through the hole structure 21.

[0062] The above-mentioned asymmetric design of the antenna unit 11 is beneficial to enhancing the excitation of local plasmons on the antenna layer 1, so that the total spontaneous radiation efficiency is further increased, the far-field radiation efficiency is further increased, and the local optical state density can be further improved, the photon radiation efficiency is increased, and the internal quantum efficiency in the tunnel junction is increased.

[0063] The working process of this tunnel junction is to apply a bias voltage to the tunnel junction, and the bias voltage is connected between the first conductive layer 2 and the second conductive layer 4, then the tunnel junction generates a tunnel current, in which some electrons lose energy through the inelastic tunneling path and excite localized plasmons on the antenna layer 1, which are then radiated to the substrate layer 5 and the dielectric space in the form of photons. In addition to being coupled to the wave, the radiation power of the tunnel junction light source is also partially scattered to the substrate layer 5 and the free space. The combination of plasmons and tunnel carriers increases the photocurrent passing through the tunnel junction.

[0064] In this embodiment, when the antenna layer 1 is placed outside the first conductive layer 2 in the basic tunnel structure, the different excitations of the plasma mode in the nanoantenna increase the probability of inelastic tunneling of electrons in the tunnel junction, thereby improving the conversion efficiency of electrons to plasmons, and plasmons to photons. The interaction between photons and tunneling current is enhanced, increasing the photocurrent passing through the tunnel junction, making the detection of photons possible. The tunnel junction in this embodiment is a new tunnel structure that includes an antenna, and is vertically stacked, which is more conducive to the tunneling of electrons.

[0065] In one embodiment, referring to Figure 1 , Figure 2 and Figure 5 As shown, when the antenna layer 1 includes multiple antenna units 11, the multiple antenna units 11 are arranged in an array on the surface of the first conductive layer 2, for example, the multiple antenna units 11 are arranged in an array along two mutually perpendicular directions on the surface of the first conductive layer 2.

[0066] Specifically, the array antenna structure can form multiple point-shaped excitation sources, and the array antenna structure can achieve the spontaneous radiation efficiency and far-field directional radiation of the point radiation source in the antenna nanogap. For the antenna parameters, electromagnetic algorithms such as the finite difference time domain method can be used to calculate the far-field distribution diagram of a single point source in the antenna array.

[0067] The array antenna structure has excellent spontaneous radiation efficiency and far-field directional radiation characteristics, which can further improve the local optical state density, increase the photon radiation efficiency, and increase the external quantum efficiency in the tunnel junction.

[0068] In one embodiment, referring to Figure 4-8 As shown, the antenna layer 1 includes multiple antenna units 11; the hole structure 21 has a rectangular opening, and the hole has two oppositely arranged wall edges (i.e., hole walls 22). Along the first direction, the projection of at least one antenna unit 11 is projected on each of the two wall edges.

[0069] Specifically, the hole opening of the hole structure 21 is rectangular, so it can be known that the hole opening of the hole structure 21 has four wall edges, of which two opposite wall edges form a group, and two wall edges in one of the two groups of wall edges are arranged opposite to the antenna unit 11 up and down, that is, when the antenna unit 11 is projected vertically downward to the first conductive layer 2 or the second conductive layer 4, the projections of some antenna units 11 cover one wall edge of the hole opening, and some antenna units 11 cover another opposite wall edge of the hole opening; of course, optionally, it is also possible that the projections of multiple antenna units 11 only cover one wall edge of the hole opening, or, optionally, it is also possible that the projections of multiple antenna units 11 cover three or four wall edges of the hole opening.

[0070] In this embodiment, the shape of the hole is designed to be a regular rectangle, which is convenient for operators to perform processing. In addition, the antenna units 11 are regularly arranged on the wall edge of the hole, which is conducive to improving the local surface plasmon resonance, increasing the probability of electron inelastic tunneling, and improving the electron-to-plasmon conversion efficiency.

[0071] In one embodiment, referring to Figure 4-8 As shown, the projection of the antenna unit 11 projected on one wall edge and the projection of the antenna unit 11 projected on the other wall edge are arranged symmetrically about the midline of the aperture.

[0072] Specifically, the midline of the hole is the midline of the rectangle; it can be understood that the number of antenna units 11 on both sides of the midline of the hole is the same, and the antenna units 11 on both sides are symmetrically arranged about the midline of the hole. Since the first direction is perpendicular to the first conductive layer 2 and the second conductive layer 4, the symmetry of the projection of the antenna unit 11 can be understood as the symmetry of the antenna unit 11.

[0073] See also Figure 4 As shown, projections of two antenna units 11 are respectively projected on the two wall edges. The design of the above quantity can be adaptively designed according to the size of the hole and the size of each antenna unit 11. Through the simulation device, the position where the localized surface plasmon resonance is more obvious is selected for layout.

[0074] In one embodiment, the areas of the antenna units 11 on both sides of the corresponding wall edge are equal, that is, for one antenna unit 11, the area of ​​the antenna unit 11 on one side of the wall edge is equal to the area of ​​the antenna unit 11 on the other side of the wall edge. It can also be said that the area of ​​the portion of the antenna unit 11 attached to the first conductive layer 2 is equal to the area of ​​the portion of the antenna unit 11 located in the hole space (when the hole structure 21 is opened in the first conductive layer 2).

[0075] In this embodiment, by designing the position of the antenna unit 11 relative to the hole and the hole wall, the relative position of the antenna unit 11 and the hole is made more regular, which is beneficial to improving the probability and stability of electron inelastic tunneling.

[0076] In one embodiment, referring to Figure 4-8 As shown, the shapes of each antenna unit 11 include rod-shaped, elliptical sheet-shaped, butterfly-shaped and tooth-shaped; when the antenna layer 1 includes multiple antenna units 11, the shapes of the multiple antenna units 11 include one or more combinations of rod-shaped, elliptical sheet-shaped, butterfly-shaped and tooth-shaped.

[0077] It can be understood that in this embodiment, the antenna layer 1 includes a plurality of antenna units 11 arranged in an array, and the shape of each antenna unit 11 can be a rod; or, the shape of each antenna unit 11 can be an elliptical plate; or, the shape of each antenna unit 11 can be a tooth plate; or, the shape of each antenna unit 11 includes a rod shape, an elliptical plate shape, a butterfly plate shape and a tooth plate shape.

[0078] Among them, the antenna unit 11 is rod-shaped, which means that the antenna unit 11 has a preset thickness or length or height, and the outer contour of the cross section of the antenna unit 11 is circular, elliptical, polygonal, etc. When the antenna unit 11 is rod-shaped, the central axis of the antenna unit 11 is parallel to the surface of the first conductive layer 2 or parallel to the array plane of the antenna layer 1, that is, the rod-shaped antenna unit 11 is placed (or lies) horizontally on the first conductive layer 2; the antenna unit 11 is elliptical sheet-shaped, which means that the antenna unit 11 has a preset thickness, and the outer contour of the cross section of the antenna unit 11 is circular, elliptical, polygonal, etc.; the antenna unit 11 is tooth-sheet-shaped, which means that the antenna unit 11 has a preset thickness, and the outer contour of the cross section of the antenna unit 11 is tooth-shaped.

[0079] When each tooth of the tooth shape is in the shape of a triangle, and one vertex of the triangle is located at the center, the outer contour of the cross section of the antenna unit 11 is in the shape of a butterfly, similar to the shape of a butterfly wing.

[0080] In this embodiment, the antenna unit 11 of the above-mentioned shape and array has a unique localized surface plasmon resonance (LSPR) characteristic; by adding a bias voltage to the tunneling structure, the localized plasmon resonates, the plasmon is combined with the tunneling current, and the external quantum efficiency of the quantum tunneling junction is significantly enhanced.

[0081] In one embodiment, referring to Figure 7 As shown, in the case where the shape of the antenna unit 11 includes a tooth-shaped shape, the tooth-shaped antenna unit 11 includes a plurality of tooth arm bodies, and the plurality of tooth arm bodies are arranged around a preset axis and at intervals; the cross-sectional outer contour shape of the tooth arm body includes a circle, an ellipse or a polygon, wherein the polygon includes a triangle, a quadrilateral, a pentagon, etc.; when the polygon is a triangle, the antenna unit 11 is butterfly-shaped; when the number of tooth arm bodies is 2, and the angle between any two adjacent tooth arm bodies is 180°, the antenna unit 11 is in the shape of a "one"-shaped tooth.

[0082] The antenna layer 1 in this embodiment is an array-type metal nanostructure, which has a unique localized surface plasmon resonance characteristic. Taking the antenna unit 11 with a triangular tooth arm as an example, the antenna unit 11 forms a butterfly structure. Therefore, the structure of the antenna layer 1 can be understood as a metal bowtie nanoantenna (BNA) structure. Its unique triangular structure can generate effective resonant plasma coupling between the tips. By changing the material, geometric parameters and dielectric environment of the BNA structure, its LSPR characteristics can be effectively regulated, thereby generating a huge enhanced electric field in the nanogap region. Its powerful electric field enhancement capability increases the proportion of inelastic tunneling current passing through the tunnel junction, thereby significantly enhancing the external quantum efficiency of the quantum tunnel junction.

[0083] In one embodiment, referring to Figure 4 As shown, a dielectric layer 6 is provided between the antenna layer 1 and the first conductive layer 2; the dielectric layer 6 is a dielectric layer 6 made of a combination of one or more of SiO2, Si3N4, Si, Al2O3, Air and hexagonal boron nitride (hBN).

[0084] During the electron tunneling process, a quantum tunneling current is generated, in which some electrons lose energy through an inelastic tunneling pathway and excite localized plasmons on the antenna array, which are then radiated into the substrate layer 5 and the dielectric layer 6 in the form of photons.

[0085] In one embodiment, the antenna layer 1 is connected to the dielectric layer 6 via an adhesive layer; the adhesive layer is a metal adhesive layer that is a combination of one or more of Ti, Cr, and Pd and is adhesive and conductive.

[0086] In one embodiment, the antenna layer 1 is an antenna layer 1 made of one or more combinations of gold materials, silver materials, copper materials and other alloy materials. The substrate layer 5 is a substrate layer made of SOI, Si, SiC, polydimethylsiloxane or glass. The first conductive layer 2 and the second conductive layer 4 are conductive layers made of two-dimensional conductive materials, and the two-dimensional conductive materials include a single layer or multiple layers of graphene and a combination of one or more molybdenum sulfide. The insulating layer 3 is an insulating layer 3 made of one or more combinations of hexagonal boron nitride, Al2O3 and SiO2.

[0087] It should be noted that SOI stands for Silicon-On-Insulator, which means silicon on an insulating substrate. This technology introduces a buried oxide layer between the top silicon and the back substrate. SOI materials have many advantages. For example, they can achieve dielectric isolation of components in integrated circuits and eliminate the parasitic door lock effect in bulk silicon CMOS circuits. Integrated circuits made of SOI materials also have the advantages of small parasitic capacitance, high integration density, fast speed, simple process, small short channel effect, and are particularly suitable for low-voltage and low-power circuits.

[0088] In addition, the thickness of the antenna layer 1 is 20nm-60nm; the thickness of the adhesion layer is 1nm-5nm; the thickness of the insulating layer 3 is 1nm-3nm. For example, the thickness of the antenna layer 1 can be 30nm, the thickness of the insulating layer 3 can be 2nm, and the thickness of the adhesion layer can be 3nm.

[0089] In a specific implementation, referring to Figure 5 As shown, the first conductive layer 2 is made of graphene material, the second conductive layer 4 is also made of graphene material, the insulating layer 3 is made of hBN material, each antenna unit 11 is rhombus-shaped, the hole is rectangular, four hole structures 21 are provided on the first conductive layer 2, and two antenna units 11 are respectively stacked on two opposite wall edges of each hole; Figure 5 As shown, it is assumed that the length of the antenna unit 11 is a, the width is b, the length direction of the antenna unit 11 is perpendicular to the wall edge of the hole, so that the antenna unit 11 is arranged on both sides of the wall edge of the hole in the length direction, then, a = 200nm, b = 50nm, the thickness of each antenna unit 11 is 30nm, the thickness of the adhesion layer is 3nm, the thickness of the insulating layer 3 is 2nm, and the bias voltage V is added between the first conductive layer 2 and the second conductive layer 4 Bias , a quantum tunneling current is generated, in which some electrons lose energy through the inelastic tunneling path and excite localized plasmons on the antenna layer 1, which are then radiated to the substrate layer 5 and the dielectric space layer in the form of photons.

[0090] With respect to the tunnel junction in the above embodiment, the performance parameters of the tunnel junction are calculated, including detecting the local optical state density, photon radiation efficiency and photon radiation power.

[0091] in, Fig. 9 The normalized local optical state density (LDOS) of the tunnel junction is shown as a function of wavelength. According to the above embodiment, the normalized local optical state density p p / ρ0 shows a clear internal quantum efficiency enhancement at the operating wavelength of 1100nm. In the nanoscale localized plasmon resonance region in the above embodiment, a strong spontaneous radiation enhancement occurs, which is five orders of magnitude stronger than the region without resonance. In this embodiment, the tunneling junction forms a two-dimensional quantum tunneling light source, in which the spontaneous radiation power is mainly determined by ohmic loss and photon radiation attenuation; among them, the spontaneous radiation power from A u The photon energy P radiated by the nanoantenna rad Most of the radiation is collected by the bottom layer and the dielectric layer 6, and the radiation efficiency can be expressed as P rad / P tot .

[0092] Fig.10 The photon radiation efficiency P of the tunnel junction is shown rad / P tot Curve varying with wavelength. According to the above embodiment, the peak radiation efficiency appears at a wavelength of 1100 nm; wherein, the operating wavelength corresponding to the highest radiation efficiency of the light source in the two-dimensional quantum tunneling light source formed by the tunnel junction in this embodiment is the same as the wavelength corresponding to the maximum spontaneous radiation value of the light source.

[0093] Fig.11 shows the normalized photon radiation power P of the tunnel junction rad / P0 curve versus wavelength; compared with the spontaneous radiation power of an electric dipole in free space, the normalized radiation power increases by five orders of magnitude when operating at the resonant frequency, reaching 1.8×10 5 .

[0094] After analysis, it can be seen that by adding antenna layer 1, the plasmons and tunneling carriers are combined, and the external quantum efficiency of the quantum tunneling junction is significantly enhanced.

[0095] In addition, by optimizing the shape, shape size, thickness size, material and other parameters of the first conductive layer 2, the second conductive layer 4, the insulating layer 3, the antenna layer 1, the dielectric layer 6 and the substrate layer 5 in the tunnel junction, the luminous intensity of the tunnel junction light source can be further improved. For example, a low dielectric constant barrier layer (insulating layer 3) and a high dielectric constant substrate layer 5 can be used, or the tunneling current density can be increased by optimizing the barrier layer. For example, the optimized barrier layer includes but is not limited to MgO material, Gd2O3 material or a double-layer tunnel barrier.

[0096] In this embodiment, graphene is modeled as a surface current density model using a local random phase approximation, and the refractive index of hBN in the near-infrared at 1100 nm is n hBN =2.2 / 2.0 (parallel / perpendicular to the plane). When a positive voltage V is applied to the second conductive layer 4 BiasWhen , some electrons inelastically tunnel through the insulating layer 3 into the first conductive layer 2 and the antenna layer 1, accompanied by the excitation of plasmons (where ), and then decays through relaxation paths such as radiation and non-radiation. The combination of plasmon and tunneling current increases the photocurrent passing through the tunneling junction, making the detection of photons possible. The tunneling structure in this embodiment can also be applied to a detector to work as a detector.

[0097] An embodiment of the present application also provides a photonic device, which includes the tunneling structure in the above embodiment, and the above photonic device includes a tunneling light source device, such as a diode, an X-ray tube, a high-power microwave tube, a cathode ray tube, etc.

[0098] In this embodiment, after the photonic device is connected to the bias voltage, the different excitations of the plasma mode in the nanoantenna increase the probability of inelastic tunneling of electrons in the tunneling junction, thereby improving the conversion efficiency of electrons to plasmons and the conversion efficiency of plasmons to photons. The combination of plasmons and tunneling electrons increases the photogenerated current passing through the tunneling junction, making the detection of photons possible.

[0099] The above are only preferred embodiments of the present application, and only specifically describe the technical principles of the present application. These descriptions are only for explaining the principles of the present application and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanation here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application, and other specific implementation methods of the present application that can be associated with the technicians in this field without creative work, should be included in the scope of protection of the present application.

Claims

1. A tunneling structure, characterized in that: It includes an antenna layer, a first conductive layer, an insulating layer, a second conductive layer and a substrate layer, wherein the antenna layer, the first conductive layer, the insulating layer, the second conductive layer and the substrate layer are stacked in sequence along a first direction; the antenna layer includes one or more antenna units stacked on the first conductive layer; at least one hole structure is opened on the first conductive layer and / or the second conductive layer, and along the first direction, the projection of each antenna unit on the first conductive layer or the second conductive layer covers both sides of the hole outline of the hole structure.

2. The tunneling structure according to claim 1, characterized in that: In the case that the antenna layer includes a plurality of antenna units, the plurality of antenna units are arranged in an array on the surface of the first conductive layer.

3. The tunneling structure according to claim 1, characterized in that: The antenna layer includes a plurality of antenna units; the hole opening of the hole structure is rectangular, and the hole opening has two wall edges arranged opposite to each other, and along the first direction, a projection of at least one antenna unit is projected onto each of the two wall edges.

4. The tunneling structure according to claim 3, characterized in that: A projection of the antenna unit projected onto one of the wall edges and a projection of the antenna unit projected onto another of the wall edges are arranged symmetrically with respect to a midline of the aperture.

5. The tunneling structure according to claim 3, characterized in that: The two wall edges are respectively provided with projections of the two antenna units.

6. The tunneling structure according to claim 3, characterized in that: The areas of the antenna units on both sides corresponding to the wall edge are equal.

7. The tunneling structure according to any one of claims 1 to 6, characterized in that: The shapes of each antenna unit include rod-shaped, elliptical plate-shaped, butterfly-shaped and tooth-shaped; when the antenna layer includes multiple antenna units, the shapes of the multiple antenna units include one or more combinations of rod-shaped, elliptical plate-shaped, plate-shaped and tooth-shaped.

8. The tunneling structure according to claim 7, characterized in that: When the shape of the antenna unit includes a tooth-shaped shape, the tooth-shaped antenna units are arranged at intervals.

9. The tunneling structure according to any one of claims 1 to 6, characterized in that: The antenna layer is an antenna layer made of one or more of a gold material, a silver material and a copper material; and / or The substrate layer is a substrate layer made of SOI, Si, SiC, polydimethylsiloxane or glass; and / or The first conductive layer and the second conductive layer are both conductive layers made of two-dimensional conductive materials; and / or The insulating layer is an insulating material that is a combination of one or more of hexagonal boron nitride, Al2O3 and SiO2.

10. The tunneling structure according to claim 9, characterized in that: The two-dimensional conductive material includes a single layer or multiple layers of graphene and a combination of one or more of molybdenum sulfide.

11. The tunneling structure according to any one of claims 1 to 6, characterized in that: The tunneling structure also includes a dielectric layer, which is located between the antenna layer and the first conductive layer; the dielectric layer is a dielectric layer made of a combination of one or more of SiO2, Si3N4, Si, Al2O3, Air and hexagonal boron nitride.

12. The tunneling structure according to any one of claims 1 to 6, characterized in that: The antenna layer is connected to the first conductive layer through an adhesive layer; the adhesive layer is a metal adhesive layer which is a combination of one or more of Ti, Cr, and Pd and has adhesiveness and conductivity.

13. The tunneling structure according to claim 12, characterized in that: The thickness of the antenna layer is 20nm-60nm; and / or The thickness of the adhesion layer is 1 nm-5 nm; and / or The thickness of the insulating layer is 1nm-3nm.

14. A photonic device, characterized in that: Comprising the tunneling structure as described in any one of claims 1-13.

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