A vertical nanometer air channel optoelectronic device with a three-terminal structure

Abstract

This application discloses a three-terminal vertical nano-air channel optoelectronic device, belonging to the field of micro / nanoelectronic and optoelectronic device technology. The device includes a substrate, a first electrode, a semiconductor photocathode, an insulating layer, a second electrode, and a third electrode. The first electrode is located on the upper surface of the substrate; the semiconductor photocathode is located on the upper surface of the first electrode; the insulating layer extends to cover the edge region of the upper surface of the semiconductor photocathode, forming an exposed active region in the center of the semiconductor photocathode; the second electrode is located on the upper surface of the semiconductor photocathode and forms direct electrical contact with the semiconductor photocathode, at least in the active region, and also includes a first independent bias port; the third electrode is suspended above the second electrode and forms a nano-air channel with the second electrode, and also includes a second independent bias port. This application utilizes a three-terminal independent bias architecture to achieve electrical decoupling between the high-speed drift transport of charge carriers within the semiconductor and the efficient electron extraction / emission process of the air channel, thereby obtaining higher emission efficiency, faster response speed, and superior optical stability.

Description

Technical Field

[0001] This application belongs to the field of micro-nano electronics and optoelectronic devices technology, and particularly relates to a three-terminal vertical nano-air channel optoelectronic device. Background Technology

[0002] As a core component that converts optical signals into electrical signals, photodetectors have wide applications in high-speed optical communication, imaging, environmental monitoring, and microwave photonics. In recent years, channel-type optoelectronic devices, which combine the high absorption rate of solid-state semiconductors with the high-speed transport of electrons in free space, have attracted attention.

[0003] Traditional free-space electronic devices rely heavily on high-vacuum environments to prevent electrons from colliding and scattering with gas molecules, resulting in high packaging costs, system complexity, and difficulty in high-density integration with micro / nano chips. In contrast, if the electron transport gap is reduced to the nanoscale, the channel length can be significantly smaller than the mean free path of electrons in air, drastically reducing the probability of inelastic collisions when electrons cross the channel. Therefore, nanoscale air channels can achieve near-ballistic ultrafast electron transit characteristics under ambient pressure, enabling low-cost packaging and on-chip integration.

[0004] However, most existing mainstream vertical nanochannel optoelectronic devices have a two-terminal structure: the photocathode and the suspended anode are directly opposite each other, and the applied voltage simultaneously performs both the functions of carrier transport within the semiconductor and electron extraction / emission through the air channel. Since the equivalent impedance of the nanochannel is typically much larger than that of the semiconductor layer, the applied voltage often drops primarily onto the nanochannel, resulting in insufficient vertical drift electric field within the semiconductor. This makes it difficult for photogenerated carriers to reach saturation drift velocity and they are prone to recombination losses within the semiconductor. Furthermore, photogenerated carriers that fail to be emitted in time tend to remain and accumulate at the semiconductor / air interface, forming a reverse electric field shielding effect that cancels out the applied electric field, reducing carrier collection efficiency and significantly degrading the response speed under strong light excitation, thus limiting the device's high-frequency response and wide dynamic range capabilities. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the prior art by providing a three-terminal vertical nano-air channel optoelectronic device that can achieve independent and adjustable transport electric field in the semiconductor and emission electric field in the air channel while maintaining the high-speed transit advantage of the nano-air channel, and effectively suppress interface charge accumulation and electric field shielding.

[0006] The objective of this application is achieved through the following technical solution: A three-terminal vertical nanochannel optoelectronic device, the device comprising a substrate, and further comprising: A first electrode, the first electrode being located on the upper surface of the substrate; A semiconductor photocathode, wherein the semiconductor photocathode is located on the upper surface of the first electrode; An insulating isolation layer extends to cover the edge region of the upper surface of the semiconductor photocathode, so that an exposed active region is formed in the center of the semiconductor photocathode; The second electrode is located on the upper surface of the semiconductor photocathode and forms a direct electrical contact with the semiconductor photocathode at least in the active region. The second electrode also includes a first independent bias port. The third electrode is suspended above the second electrode and forms a nano-air channel between the third electrode and the second electrode. The third electrode also includes a second independent bias port.

[0007] Furthermore, the device establishes a vertical drift electric field inside the semiconductor photocathode through the bias between the first electrode and the second electrode.

[0008] Furthermore, the device establishes an electron extraction / emission electric field within the nano-air channel through a bias between the second and third electrodes.

[0009] Furthermore, the second electrode includes an ultrathin conductive layer, which comprises a two-dimensional conductive material monolayer structure or an ultrathin conductive film.

[0010] Furthermore, the second electrode includes a hole array structure, which includes multiple micro- and nano-scale through holes.

[0011] Furthermore, the second electrode is one or more of the following: an optically transparent metasurface electrode structure, a nanomesh electrode, a transparent metal mesh electrode, a nanowire electrode, or a periodically perforated electrode.

[0012] Furthermore, a support structure is formed on top of the insulating layer to support the third electrode and define the spacing of the nano-air channels.

[0013] Furthermore, the second electrode clamps the surface potential of the semiconductor photocathode in the active region.

[0014] The beneficial effects of this application are as follows: This application provides independent bias ports for the second and third electrodes, which can establish the internal drift electric field of the semiconductor and the extracted electric field of the nano air channel through two sets of biases: the first electrode-second electrode and the second electrode-third electrode, respectively, thus avoiding the clamping of the internal electric field of the semiconductor by the high-impedance air channel.

[0015] This application divides electron motion into a drift transport stage within a semiconductor and an emission / transfer stage within a nano-air channel, and controls each stage as needed to ensure that each stage is in a better energy and velocity state.

[0016] The second electrode of this application is in direct electrical contact with the semiconductor photocathode in the active region, which can clamp the interface potential and provide a charge discharge channel, significantly weakening or eliminating the reverse shielding electric field caused by the accumulation of photogenerated carriers, thereby improving the response stability and linear dynamic range under strong light.

[0017] The second electrode of this application is in direct electrical contact with the semiconductor photocathode in the active region and its surface potential is clamped by external bias, thereby providing a low-resistance discharge path for photogenerated carriers at the interface, suppressing charge accumulation and reducing the electric field shielding effect.

[0018] The three-terminal vertical nano-air channel optoelectronic device proposed in this application can be used for applications such as high-speed photoelectric detection, photoelectric gating, photoelectron emission, and millimeter-wave / terahertz photoelectric mixing. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a three-terminal vertical nano-air channel optoelectronic device. Figure 2 This is a simulation comparison diagram showing the change of electric field intensity along the vertical direction with position between a three-terminal structure and a traditional two-terminal structure. Figure 3 This is a schematic diagram of the two-dimensional electrostatic field distribution and carrier extraction trajectory when the second electrode is a grid / hole array structure.

[0020] Reference numerals: 11-substrate, 12-first electrode, 13-semiconductor photocathode, 14-insulating layer, 15-second electrode, 16-third electrode. Detailed Implementation

[0021] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0022] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Most current mainstream vertical nanochannel optoelectronic devices have a two-terminal structure: the photocathode and the suspended anode are directly opposite each other, and the applied voltage simultaneously performs both carrier transport within the semiconductor and electron extraction / emission through the air channel. Since the equivalent impedance of the nanochannel is typically much larger than that of the semiconductor layer, the applied voltage often drops primarily across the nanochannel, resulting in insufficient vertical drift electric field within the semiconductor. This makes it difficult for photogenerated carriers to reach saturation drift velocity and they are prone to recombination losses within the semiconductor. Furthermore, photogenerated carriers that fail to be emitted in time tend to remain and accumulate at the semiconductor / air interface, forming a reverse electric field shielding effect that cancels out the applied electric field, reducing carrier collection efficiency and significantly degrading response speed under strong light excitation, thus limiting the device's high-frequency response and wide dynamic range capabilities.

[0024] To address the aforementioned technical problems, the present application proposes the following embodiments of a three-terminal vertical nano-air channel optoelectronic device.

[0025] Reference Figure 1 ,like Figure 1 The diagram shows a three-terminal vertical nano-air channel optoelectronic device.

[0026] The device in this embodiment includes, from bottom to top, a substrate 11, a first electrode 12, and a semiconductor photocathode 13. The semiconductor photocathode 13 can be etched to form a mesa structure; an insulating layer 14 covers its sidewalls and surface edge areas to retain an exposed active region in the center of the semiconductor photocathode 13. A second electrode 15 covers the active region and forms direct electrical contact with the semiconductor photocathode 13; the second electrode 15 extends outward to form an independent bias port. A third electrode 16 is suspended and supported on the insulating layer 14 or its top support structure, maintaining a nanoscale physical gap between the third electrode 16 and the second electrode 15, forming a nanoscale air channel.

[0027] The first electrode 12 is the lower electrode or back electrode, the second electrode 15 is the control electrode, and the third electrode 16 is the upper electrode, anode, or collection electrode.

[0028] In this embodiment, the substrate 11 is an insulating substrate, a semi-insulating substrate, or a combination thereof, and can be made of materials such as SiO2, Al2O3, AlN, SiC, semi-insulating Si, InP, etc. The first electrode 12 can be made of highly doped semiconductors, metals, alloys, semi-metals, two-dimensional conductive materials, or transparent conductive oxides, etc. The semiconductor photocathode 13 can be made of materials such as Si, Ge, InGaAs, GaAs, etc. The insulating isolation layer 14 can be made of materials such as SiO2, Si3N4, Al2O3, etc. The second electrode can be made of materials such as single-layer / few-layer two-dimensional conductive materials, ultrathin conductive films, or metal mesh / hole array electrodes, etc. The third electrode can be made of materials such as highly doped semiconductors, metals, alloys, semi-metals, two-dimensional conductive materials, or transparent conductive oxides, etc.

[0029] During operation, a first bias is applied between the first electrode 12 and the second electrode 15 to establish a vertical drift electric field inside the semiconductor photocathode 13, driving photogenerated carriers to drift at high speed within the bulk. A second bias is applied between the second electrode 15 and the third electrode 16 to establish an extraction electric field within the nano-air channel, enabling electrons to enter the air channel from the interface and rapidly cross over to the third electrode 16. The two biases are independently adjustable, thereby achieving electrical decoupling between the transport and emission processes.

[0030] As an example, the vertical spacing of the nano-air channels can be 1 nm–1000 nm, preferably 20 nm–100 nm; the thickness of the semiconductor photocathode 13 can be 50 nm–1000 nm, preferably 100 nm–500 nm.

[0031] As one implementation method, this embodiment presents a device implementation method and effect verification based on the hot electron near-ballistic penetration mechanism.

[0032] The second electrode 15 is an ultrathin conductive film / two-dimensional conductive material layer, which is a single-layer or few-layer structure of two-dimensional conductive material, or its thickness is 0.3 nm to 10 nm (preferably less than 1 nm), in order to reduce the inelastic scattering and energy relaxation of electrons when passing through the second electrode 15 and increase the probability of electron injection into the nano-air channel.

[0033] The working mechanism can be described as follows: By adjusting the bias between the first electrode 12 and the second electrode 15, a strong vertical drift electric field is formed in the semiconductor photocathode 13, which accelerates the photogenerated electrons toward the surface and gives them higher kinetic energy; at the same time, the extraction electric field between the second electrode 15 and the third electrode 16 forms an ultra-strong field in the nano air channel, which can reduce the interface barrier and increase the probability of electrons being injected into the air channel, so that electrons cross the interface and enter the nano air channel with a higher probability and are collected by the third electrode 16.

[0034] As one implementation method, this embodiment uses multiphysics simulation software to numerically simulate the longitudinal electrostatic field distribution. (Refer to...) Figure 2 ,like Figure 2 The diagram shows a simulation comparison of the electric field intensity along the vertical direction of the three-terminal structure and the traditional two-terminal structure as a function of position.

[0035] In the example model, the semiconductor photocathode 13 has a thickness of 300 nm, is made of Ge, and has a nano-air channel spacing of 50 nm. For conventional two-terminal structures (lacking a second electrode clamping), even with a 5 V or 10 V applied to the third electrode, the electric field inside the semiconductor layer remains significantly weak (example value approximately 0.6 MV / m), making it difficult to drive carriers to reach saturation drift velocity. In contrast, the three-terminal structure of this invention introduces a second electrode 15 to clamp the interface potential and significantly enhances the electric field inside the semiconductor through independent biasing (example value up to approximately 16.4 MV / m), while the nano-air channels maintain a high extraction electric field, thus achieving a balance between high-speed transport and efficient emission within the bulk.

[0036] As one implementation method, this embodiment presents a device implementation method and effect verification based on geometric field emission and "electron lens" mechanism.

[0037] In this embodiment, the second electrode 15 is a mesh structure or a hole array structure with multiple micro-nano scale through holes; the hole diameter is 10 nm to 5 µm, and / or the porosity is 5% to 95%. The second electrode 15 can be one or more of the following: an optically transparent metasurface electrode structure, a nanomesh electrode, a metal mesh transparent electrode, a nanowire electrode, or a periodically perforated electrode, to balance light transmission, electrical conductivity, and electric field distribution modulation.

[0038] Reference Figure 3 ,like Figure 3 The diagram illustrates the two-dimensional electrostatic field distribution and carrier extraction trajectory when the second electrode has a grid / hole array structure. When the second electrode 15 has through holes, the extraction electric field within the nano-air channel can penetrate downwards to the surface of the semiconductor photocathode 13 through the through holes, causing distortion of the equipotential surface near the holes and forming a local focusing field. Under the synergistic push-pull effect of the drift electric field inside the semiconductor and the extraction electric field of the air channel, the three-dimensional trajectory of electrons can be guided and focused through the through-hole region into the nano-air channel, thereby reducing collision scattering and energy loss between electrons and the body material of the second electrode, improving emission efficiency and device stability.

[0039] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A three-terminal vertical nanochannel optoelectronic device, the device comprising a substrate, characterized in that, The device also includes: A first electrode, the first electrode being located on the upper surface of the substrate; A semiconductor photocathode, wherein the semiconductor photocathode is located on the upper surface of the first electrode; An insulating isolation layer extends to cover the edge region of the upper surface of the semiconductor photocathode, so that an exposed active region is formed in the center of the semiconductor photocathode; The second electrode is located on the upper surface of the semiconductor photocathode and forms a direct electrical contact with the semiconductor photocathode at least in the active region. The second electrode also includes a first independent bias port. The third electrode is suspended above the second electrode and forms a nano-air channel between the third electrode and the second electrode. The third electrode also includes a second independent bias port.

2. The vertical nano-air channel optoelectronic device with a three-terminal structure as described in claim 1, characterized in that, The device establishes a vertically drifting electric field inside the semiconductor photocathode through a bias between the first electrode and the second electrode.

3. The vertical nano-air channel optoelectronic device with a three-terminal structure as described in claim 1, characterized in that, The device establishes an electron extraction / emission electric field within the nano-air channel through a bias between the second and third electrodes.

4. The vertical nano-air channel optoelectronic device with a three-terminal structure as described in claim 1, characterized in that, The second electrode includes an ultrathin conductive layer, which comprises a two-dimensional conductive material monolayer structure or an ultrathin conductive film.

5. The vertical nano-air channel optoelectronic device with a three-terminal structure as described in claim 1, characterized in that, The second electrode includes a hole array structure, which includes multiple micro- and nano-scale through holes.

6. The vertical nano-air channel optoelectronic device with a three-terminal structure as described in claim 5, characterized in that, The second electrode is one or more of the following: an optically transparent metasurface electrode structure, a nanomesh electrode, a transparent metal mesh electrode, a nanowire electrode, or a periodically perforated electrode.

7. The vertical nano-air channel optoelectronic device with a three-terminal structure as described in claim 1, characterized in that, A support structure is formed on top of the insulating layer to support the third electrode and define the spacing of the nano-air channels.

8. The vertical nano-air channel optoelectronic device with a three-terminal structure as described in claim 1, characterized in that, The second electrode clamps the surface potential of the semiconductor photocathode in the active region.

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