A gallium oxide deep ultraviolet photodetector and a preparation method thereof

Abstract

The application discloses a gallium oxide deep ultraviolet photodetector and a preparation method thereof. The gallium oxide deep ultraviolet photodetector comprises a super-thin wide-band-gap barrier layer between a gallium oxide layer and an electrode or between an N-type gallium oxide layer and a P-type semiconductor layer; the super-thin wide-band-gap barrier layer is formed of at least one material selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide and aluminum nitride in a single layer or a multi-layer laminated structure. The gallium oxide deep ultraviolet photodetector can not only effectively saturate the dangling bonds on the surface of the gallium oxide, reduce the interface trap state density and inhibit the leakage caused by defect-assisted tunneling, but also can form a tunnel heterojunction together with the gallium oxide layer and other layers, thereby maintaining a high photocurrent response, reducing the dark current, improving the light-to-dark current ratio of the device and the signal-to-noise ratio.

Description

Technical Field

[0001] This application relates to the field of deep ultraviolet light detection technology, and in particular to a gallium oxide deep ultraviolet photodetector and its fabrication method. Background Technology

[0002] Deep ultraviolet (DUV) photodetector technology has significant application value and broad market prospects in fields such as flame early warning, ozone layer monitoring, space communication, biochemical analysis, and high-voltage corona detection. Compared to the complex schemes of traditional silicon-based photodetectors that require filtering systems to achieve DUV detection, ultrawide bandgap semiconductor gallium oxide (GaO) has become an ideal candidate material for constructing high-sensitivity DUV detectors due to its natural matching characteristics to the DUV band, high radiation resistance, good chemical stability, high breakdown electric field strength, and low-cost growth capabilities.

[0003] Currently, gallium oxide deep ultraviolet photodetectors can be classified into three types according to their device structure: metal-semiconductor-metal (MSM) detectors, thin-film transistor (TFT) detectors, and PN junction detectors. Among them, MSM detectors have advantages such as simple structure, good process compatibility, and fast response speed, and have been widely studied. TFT structures, compared to MSM structures, have an additional gate electrode control terminal, adjustable gain, and are convenient for pixelated arrays and active matrix addressing, making them the preferred structure for imaging arrays. However, gallium oxide inherently possesses a high oxygen vacancy defect density and abundant surface defect states, resulting in severe Fermi level pinning and defect-assisted tunneling at the metal / semiconductor interface. This leads to a large leakage current in dark conditions, severely limiting the improvement of the photocurrent-to-dark-current ratio. PN junction gallium oxide detectors utilize a built-in electric field to separate photogenerated carriers, enabling self-powered operation under zero bias. However, gallium oxide lacks effective p-type doping capability, making the fabrication of homogeneous PN junctions extremely difficult. To overcome this difficulty, researchers have attempted to construct heterojunctions with n-type gallium oxide by combining p-type oxide semiconductors, such as nickel oxide (NiO), copper aluminum oxide (CuAlO2), and cuprous oxide (Cu2O). However, due to factors such as lattice mismatch and interfacial chemical reactions, a large number of interface states are often introduced at the heterojunction, becoming carrier recombination centers and leakage channels, which also limits the device's photocurrent-to-dark-current ratio and detection sensitivity.

[0004] Therefore, how to solve the technical problems of large dark current, low photocurrent-to-dark-current ratio and high surface and interface defect density of existing gallium oxide deep ultraviolet detectors remains the research focus and difficulty in the field of gallium oxide deep ultraviolet photodetector technology. Summary of the Invention

[0005] The purpose of this application is to provide an improved gallium oxide deep ultraviolet photodetector and its fabrication method.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] This application discloses a gallium oxide deep ultraviolet photodetector, comprising adding an ultrathin wide bandgap barrier layer between a gallium oxide layer and an electrode, or between an N-type gallium oxide layer and a P-type semiconductor layer; wherein the ultrathin wide bandgap barrier layer is formed into a single-layer or multi-layer stacked structure of at least one material selected from aluminum oxide, zirconium oxide, hafnium oxide, and aluminum nitride. The single-layer or multi-layer stacked structure can be, for example, a single-layer or multi-layer stacked structure formed of a single material, or a single-layer or multi-layer stacked structure formed of a mixture of multiple materials, or a multi-layer stacked structure in which each layer uses a different material.

[0008] It should be noted that the key to this application lies in adding an ultrathin, wide-bandgap barrier layer formed from at least one of the following materials: aluminum oxide, zirconium oxide, hafnium oxide, and aluminum nitride, to the existing gallium oxide deep ultraviolet photodetector. This ultrathin, wide-bandgap barrier layer serves a dual function as an interface passivation and tunneling barrier. On one hand, the ultrathin, wide-bandgap barrier layer effectively saturates the dangling bonds on the gallium oxide surface, reduces the density of interface trap states, and suppresses leakage current caused by defect-assisted tunneling. On the other hand, the ultrathin, wide-bandgap barrier layer, the gallium oxide layer, and the electrode or P-type semiconductor layer together constitute a tunnel heterojunction. Under dark conditions, the ultrathin, wide-bandgap barrier layer superimposes with the metal / gallium oxide Schottky barrier to form a high barrier, effectively blocking carrier transport and significantly suppressing dark current. Under deep ultraviolet illumination and reverse bias, the gallium oxide layer absorbs photons to generate electron-hole pairs. Driven by the built-in electric field, the photogenerated holes drift towards the heterojunction and are effectively captured by deep-level interface traps, forming a localized positive space charge layer. This positive charge layer partially shields the electric field from the metal side, effectively introducing a positive potential onto the semiconductor surface. This causes the width of the semiconductor depletion layer to decrease monotonically with the accumulation of interface charge density. The geometric compression of the depletion layer significantly shortens the electron tunneling integral path, resulting in an exponential increase in the electron transmission coefficient, thereby achieving efficient cross-junction transport of photogenerated carriers. Through this adaptive carrier modulation mechanism of "high resistance in the dark state and low conductance in the light state," this application significantly reduces dark current while maintaining a high photocurrent response, significantly improving the device's photocurrent-to-dark-current ratio and signal-to-noise ratio. This application has a simple structure, is highly compatible with existing semiconductor processes, and can be widely applied in deep ultraviolet detection, flame early warning, and space communication.

[0009] In some implementations, the thickness of the ultrathin wide bandgap barrier layer is 1-20 nm.

[0010] It should be noted that the ultrathin wide bandgap barrier layer of this application cannot be too thin or too thick. If the ultrathin wide bandgap barrier layer is too thin, for example, less than 1 nm, it is difficult to form a continuous and uniform film, which cannot effectively passivate the defect states on the gallium oxide surface, and the tunneling barrier is too low, resulting in insufficient dark current suppression. Conversely, if the thickness is greater than 10 nm, the tunneling probability of charge carriers is significantly reduced, hindering the cross-junction transport of photogenerated charge carriers, resulting in a significant decrease in photocurrent response. Therefore, the thickness of the ultrathin wide bandgap barrier layer in this application is preferably 1-20 nm, and more preferably 1-5 nm. Within this range, the wide bandgap barrier layer can provide sufficient interface passivation effect and ensure efficient tunneling transport of photogenerated charge carriers under illumination conditions.

[0011] In some implementations, the gallium oxide layer or N-type gallium oxide layer is β-phase gallium oxide with a thickness of 10 nm-10 μm.

[0012] It should be noted that the required thickness of the gallium oxide layer or the N-type gallium oxide layer varies depending on the different device structure types of gallium oxide deep ultraviolet photodetectors. For example, for MSM-type detectors, the gallium oxide epitaxial layer is unintentionally doped n-type gallium oxide, with a carrier concentration range of 1×10⁻⁶. 15 -1×10 17 cm -3 The thickness is 10 nm-10 μm; for TFT detectors, the gallium oxide epitaxial layer or channel layer is 10 nm-500 nm; for PN junction detectors, the doping concentration of the N-type gallium oxide epitaxial layer is 1×10⁻⁶. 16 -1×10 18 cm -3 The thickness is 10nm-1000 nm.

[0013] In some implementations, the gallium oxide deep ultraviolet photodetector is at least one of an MSM-type detector, a bottom-gate TFT detector, a top-gate TFT detector, and a PN junction detector.

[0014] In some implementations, the MSM-type detector includes a substrate, a gallium oxide layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the gallium oxide layer, and interdigitated electrodes fabricated on the ultrathin wide bandgap barrier layer.

[0015] It should be noted that, in this application, the metal material of the interdigitated electrode is selected from titanium / gold (Ti / Au) multilayer metal. As a preferred embodiment, one side of the interdigitated electrode undergoes a rapid thermal annealing process to form an ohmic contact, while the other side is not annealed to maintain a Schottky contact, together with the ultrathin alumina layer and gallium oxide layer, forming a metal-wide bandgap barrier-gallium oxide tunnel heterojunction.

[0016] In some implementations, the bottom-gate TFT detector includes a substrate, a gate electrode disposed on the substrate, a gate dielectric layer disposed on the gate electrode, a gallium oxide layer disposed on the gate dielectric layer, an ultrathin wide bandgap barrier layer disposed on the gallium oxide layer, and a source electrode and a drain electrode disposed on the ultrathin wide bandgap barrier layer.

[0017] In some implementations, the top-gate TFT detector includes a substrate, a gallium oxide layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the gallium oxide layer, a source electrode, a drain electrode, and a gate dielectric layer disposed on the ultrathin wide bandgap barrier layer, and a gate electrode disposed on the gate dielectric layer.

[0018] It should be noted that in this application, the gate dielectric layer is selected from silicon oxide, aluminum oxide, hafnium oxide, zirconium oxide, or silicon nitride, and its thickness is 10 nm-200 nm. As a preferred embodiment, the source electrode undergoes a rapid thermal annealing process to form an ohmic contact, while the drain electrode does not undergo an annealing process to maintain a Schottky contact, together with the ultrathin wide bandgap layer and the gallium oxide layer, forming a metal-wide bandgap barrier-gallium oxide tunnel heterojunction.

[0019] In some implementations, the PN junction detector includes a substrate, an N-type gallium oxide layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the N-type gallium oxide layer, a P-type semiconductor layer disposed on the ultrathin wide bandgap barrier layer, and an N-type electrode and a P-type electrode that form ohmic contacts with the N-type gallium oxide layer and the P-type semiconductor layer, respectively.

[0020] In some implementations, the p-type semiconductor layer is formed of at least one material selected from nickel oxide (NiO), copper aluminum oxide (CuAlO2), cuprous oxide (Cu2O), copper gallium oxide (CuGaO2), copper chromium oxide (CuCrO2), nickel cobalt oxide (NiCo2O4), tin oxide (SnO), cuprous sulfide (Cu2S), cuprous iodide sulfide (Cu2IS), p-type gallium nitride, p-type silicon carbide, p-type aluminum nitride, and p-type diamond.

[0021] It should be noted that, in this application, nickel oxide (NiO) is the preferred option due to its bandgap of approximately 3.7 eV and relatively good lattice matching with gallium oxide; copper-iron oxide p-type oxides such as copper-aluminum oxide (CuAlO2) and copper-gallium oxide (CuGaO2) are also feasible options due to their high light transmittance and good p-type conductivity. In this application, the thickness of the p-type semiconductor layer is 50-500 nm, and the materials of the N-type electrode and the p-type electrode are selected from titanium / gold (Ti / Au) and nickel / gold (Ni / Au) multilayer metals, respectively.

[0022] It should also be noted that in this application, the substrate is selected from any one of sapphire (c-plane Al2O3) substrate, gallium oxide single crystal substrate, and silicon substrate. For bottom-gate TFT devices, a heavily doped conductive substrate, such as a heavily doped Si substrate, is preferred as both the substrate and the gate electrode. For other device structures, c-plane sapphire substrates are preferred due to their smaller lattice mismatch with gallium oxide (approximately 4.8%), lower cost, and higher ultraviolet transmittance.

[0023] This application also discloses a method for fabricating a gallium oxide deep ultraviolet photodetector, including the use of atomic layer deposition technology to fabricate an ultrathin wide bandgap barrier layer on the gallium oxide layer or the N-type gallium oxide layer.

[0024] In some implementations, the deposition temperature for atomic layer deposition is 80-300℃.

[0025] Due to the adoption of the above technical solutions, the beneficial effects of this application are as follows:

[0026] The gallium oxide deep ultraviolet photodetector of this application has an ultrathin wide bandgap barrier layer that can not only effectively saturate the dangling bonds on the gallium oxide surface, reduce the density of interface trap states, and suppress leakage current caused by defect-assisted tunneling, but also form a tunnel heterojunction together with the gallium oxide layer and other layers. This reduces dark current while maintaining high photocurrent response, thereby improving the photocurrent-to-dark-current ratio and signal-to-noise ratio of the device. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the MSM-type gallium oxide deep ultraviolet photodetector in the embodiments of this application;

[0028] Figure 2 This is a top view of the MSM-type gallium oxide deep ultraviolet photodetector in an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of the energy band of the tunnel junction in the MSM-type and TFT-type gallium oxide detectors in the embodiments of this application under dark and light conditions, where (a) is the dark condition and (b) is the deep ultraviolet light condition;

[0030] Figure 4 This is a cross-sectional view of a TFT-type gallium oxide deep ultraviolet photodetector in an embodiment of this application, where (a) is a bottom-gate type and (b) is a top-gate type.

[0031] Figure 5 This is a schematic cross-sectional view of a PN junction type gallium oxide deep ultraviolet photodetector in an embodiment of this application, where (a) is a coplanar electrode type and (b) is a non-coplanar electrode type.

[0032] Figure 6This is a schematic diagram of the energy band of the tunnel junction in the PN junction type gallium oxide detector under dark and light conditions in the embodiments of this application, where (a) is the dark condition and (b) is the deep ultraviolet light condition;

[0033] Figure 7 The diagram shows a comparison of the current-voltage characteristics of the MSM-type device in the embodiments of this application and the conventional MSM device without a wide bandgap barrier layer. (a) shows the test results of the conventional MSM device without a wide bandgap barrier layer, and (b) shows the test results of the MSM-type device in the embodiments.

[0034] In the diagram, the markings are as follows: 10 is the substrate, 20 is the gallium oxide epitaxial layer, 30 is the ultrathin wide bandgap barrier layer, 40 is the unilateral interdigitated electrode of the ohmic contact, 50 is the unilateral interdigitated electrode of the Schottky contact, 11 is the substrate, 21 is the gallium oxide channel layer, 31 is the ultrathin wide bandgap barrier layer, 41 is the source electrode, 51 is the drain electrode, 61 is the gate electrode, 71 is the gate dielectric layer, 12 is the substrate, 22 is the n-type gallium oxide epitaxial layer, 32 is the ultrathin wide bandgap barrier layer, 42 is the n-type electrode, 52 is the p-type electrode, and 82 is the p-type semiconductor layer. Detailed Implementation

[0035] To overcome the technical bottlenecks of existing gallium oxide deep ultraviolet detectors, such as large dark current, low photocurrent-to-dark current ratio, and high surface and interface defect density, this application develops a gallium oxide deep ultraviolet detector and its fabrication method that can effectively passivate gallium oxide surface and interface defect states, suppress dark current, and maintain efficient cross-interface transport of photogenerated carriers. This has significant research significance and practical value for breaking through the performance limits of existing Ga2O3 deep ultraviolet detectors and achieving high photocurrent-to-dark current ratio and high sensitivity detection.

[0036] The gallium oxide deep ultraviolet photodetector of this application introduces an ultrathin wide bandgap barrier layer between the gallium oxide layer and the metal electrode (MSM structure and TFT structure) or between the N-type gallium oxide layer and the P-type semiconductor layer (PN junction structure). This ultrathin wide bandgap barrier layer has the dual functions of interface passivation and tunneling barrier. The technical solution of this application is applicable to all existing gallium oxide deep ultraviolet photodetectors with different device structures, namely metal-semiconductor-metal (MSM) detectors, thin-film transistor (TFT) detectors, and PN junction detectors.

[0037] For example, a metal-semiconductor-metal (MSM) type gallium oxide deep ultraviolet photodetector has the following structure from bottom to top: a substrate, a gallium oxide epitaxial layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the gallium oxide epitaxial layer, and interdigitated electrodes fabricated on the upper surface of the ultrathin wide bandgap barrier layer. The ultrathin wide bandgap barrier layer is introduced between the gallium oxide epitaxial layer and the interdigitated electrodes to form a metal-wide bandgap barrier-gallium oxide tunnel junction structure.

[0038] The thin-film transistor (TFT) type gallium oxide deep ultraviolet photodetector of this application can be divided into two structures according to its gate layout: bottom-gate and top-gate. The bottom-gate structure, from bottom to top, includes: a substrate, a gate electrode disposed on the substrate, a high-k oxide gate dielectric layer disposed on the gate electrode, a gallium oxide channel layer disposed on the gate dielectric layer, an ultrathin wide bandgap barrier layer disposed on the gallium oxide channel layer, and a source electrode and a drain electrode disposed on the wide bandgap barrier layer. The top-gate structure, from bottom to top, includes: a substrate, a gallium oxide channel layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the gallium oxide channel layer, a source electrode, a drain electrode, and a high-k oxide gate dielectric layer disposed on the wide bandgap barrier layer, and a gate electrode disposed on the gate dielectric layer. The ultrathin wide bandgap barrier layer is introduced between the gallium oxide channel layer and the source / drain electrodes to form a metal-wide bandgap barrier-gallium oxide tunnel junction structure.

[0039] The PN junction type gallium oxide deep ultraviolet photodetector of this application comprises: a substrate, an N-type gallium oxide epitaxial layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the N-type gallium oxide epitaxial layer, a P-type semiconductor layer disposed on the ultrathin wide bandgap barrier layer, an N-type electrode forming an ohmic contact with the N-type gallium oxide epitaxial layer, and a P-type electrode forming an ohmic contact with the P-type semiconductor layer. The ultrathin wide bandgap barrier layer is introduced between the N-type gallium oxide epitaxial layer and the P-type semiconductor layer, forming a P-type semiconductor-wide bandgap barrier-N-type gallium oxide tunnel heterojunction structure.

[0040] The core innovative mechanism of this application lies in the fact that the ultrathin wide bandgap barrier layer possesses the dual functions of interface passivation and tunneling barrier. On the one hand, the wide bandgap barrier layer passivates surface defect states through dangling bonds on the saturated gallium oxide surface, significantly reducing the interface state density and thus suppressing leakage current caused by defect-assisted tunneling. On the other hand, the ultrathin wide bandgap barrier layer (1-20nm), together with the gallium oxide layer and the metal electrode (or P-type semiconductor layer), constitutes a tunnel heterojunction. Under dark conditions, the conduction band step between the wide bandgap barrier layer and gallium oxide forms a high tunneling barrier, effectively blocking the thermal emission and tunneling transport of charge carriers, and significantly suppressing dark current. Under deep ultraviolet illumination and reverse bias, gallium oxide absorbs light to generate electron-hole pairs. Photogenerated holes drift to the heterojunction under the drive of the built-in electric field and are captured by deep-level interface traps, forming a localized positive space charge layer. This positively charged layer partially shields the electric field on the metal side, effectively introducing a positive surface potential, causing the width of the semiconductor depletion layer to decrease monotonically with the accumulation of interface charge. The geometric compression of the depletion layer significantly shortens the electron tunneling integral path, resulting in an exponential increase in the electron transmission coefficient and achieving efficient cross-junction transport of photogenerated carriers.

[0041] Specifically, taking the Al2O3 / β-Ga2O3 interface as an example, the conduction band level ΔEC is approximately 1.7 eV, and the valence band level ΔEV is approximately 0.8 eV. This band matching requires electrons to cross a sufficient barrier height for transport from gallium oxide to the electrode (or p-type layer). Under low bias in the dark state, both thermionic emission current and direct tunneling current are effectively suppressed. Under illumination, photogenerated holes accumulate at the interface to form a positive space charge layer, increasing the built-in field and decreasing the effective tunneling barrier width. This leads to a sharp increase in Fowler-Nordheim tunneling and direct tunneling currents, forming an adaptive carrier modulation mechanism of "high resistance in the dark state and low conductance in the light state." Through this mechanism, this application significantly reduces dark current while maintaining high photocurrent response, significantly improving the device's photocurrent-to-dark-current ratio, signal-to-noise ratio, and specific detectivity.

[0042] Compared with the prior art, this application has the following advantages:

[0043] (1) Significantly improved photo-to-dark-current ratio: Through the adaptive control mechanism of "high resistance in dark state and low conductance in light state" of the ultrathin wide bandgap barrier tunnel junction, the dark current can be suppressed to the level of 0.1 pA, and the photo-to-dark-current ratio can be improved to 10. 7 The magnitude is at least one order of magnitude higher than that of traditional MSM structure devices.

[0044] (2) Improved response speed: The reduction of interface defect states effectively suppresses the continuous photoconductivity (PPC) effect, and the rise / fall time of the device can be shortened to the millisecond or even microsecond level.

[0045] (3) Simple structure and compatible process: The device structure of the present invention is simple, without the need for complex multilayer epitaxial or micro-nano structure processing, and is fully compatible with existing semiconductor planar processes, making it easy to realize large-scale array fabrication and system integration.

[0046] (4) Flexible material selection and wide adaptability: This application covers a variety of ultra-wide bandgap barrier layer materials and their stacked structures, such as Al2O3, ZrO2, HfO2 and AlN; a variety of gate dielectric layer materials, such as Al2O3, ZrO2, HfO2 and SiO2; and a variety of p-type semiconductor materials, such as NiO, CuAlO2, CuGaO2 and Cu2O. The material combination can be flexibly selected according to the requirements of different application scenarios for detection sensitivity, response speed and power consumption.

[0047] The present application will be further described in detail below through specific embodiments. The following embodiments are only for further illustration of the present application and should not be construed as limiting the present application.

[0048] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0049] Example 1

[0050] This example adds an ultrathin, wide-bandgap Al2O3 barrier layer to the MSM-type detector to form a tunnel junction, as detailed below:

[0051] 1. Device Structure

[0052] This example demonstrates an MSM-type gallium oxide deep ultraviolet photodetector based on Al2O3 tunnel junction modulation, the structure of which is as follows: Figure 1 and Figure 2 As shown, it includes:

[0053] Substrate 10: Sapphire substrate, double-sided polished, with a thickness of 430 μm.

[0054] Gallium oxide epitaxial layer 20: A β-phase gallium oxide epitaxial layer disposed on the substrate 10.

[0055] Ultrathin wide bandgap barrier layer 30: An ultrathin Al2O3 layer with a thickness of 2 nm is disposed on the gallium oxide epitaxial layer 20.

[0056] Interdigitated electrodes 40 and 50: Interdigitated electrodes fabricated on the surface of the ultrathin wide bandgap barrier layer 30, made of Ti / Au, with a Ti thickness of 30 nm and an Au thickness of 100 nm. The interdigitated electrodes have a finger width of 3 μm, a finger spacing of 6 μm, and 4 pairs of interdigitated fingers.

[0057] The interdigitated electrodes include a single-sided electrode 40 that has formed an ohmic contact with the semiconductor through a rapid thermal annealing process, and a single-sided electrode 50 that has maintained a Schottky contact with the semiconductor without annealing.

[0058] 2. Preparation method

[0059] The fabrication method of the MSM-type detector in this example includes the following steps:

[0060] S1: Substrate cleaning. The sapphire substrate was ultrasonically cleaned in acetone, anhydrous ethanol and deionized water for 10 minutes each, and then dried with high-purity nitrogen.

[0061] S2: Gallium oxide epitaxial layer growth. A β-Ga2O3 thin film was epitaxially grown on a sapphire substrate using metal-organic chemical vapor deposition (MOCVD) with trimethylgallium (TMGa) as the gallium source and oxygen as the oxygen source, resulting in a β-Ga2O3 epitaxial layer with a thickness of approximately 500 nm.

[0062] S3: Preparation of an ultrathin Al2O3 layer. An Al2O3 thin film was deposited on a β-Ga2O3 layer using atomic layer deposition (ALD) technology. The precursors were trimethylaluminum (TMA) and water. The deposition temperature was 200°C, the number of cycles was approximately 20, and the deposition rate was approximately 0.1 nm / cycle, resulting in an ultrathin Al2O3 layer with a thickness of approximately 2 nm.

[0063] S4: Fabrication of a single-sided metal electrode. A single-sided Ti / Au interdigitated electrode was fabricated on the surface of an Al2O3 layer using ultraviolet lithography and electron beam evaporation. Specifically, the photoresist pattern for the interdigitated electrode was first formed on the surface of the Al2O3 layer using ultraviolet lithography; then, a Ti layer (30 nm) and an Au layer (100 nm) were sequentially deposited using electron beam evaporation; finally, the photoresist was removed using a lift-off process to obtain the single-sided interdigitated metal electrode.

[0064] S5: Annealing to form ohmic contacts. The sample obtained in step S4 is subjected to a rapid thermal annealing process to achieve ohmic contacts between the single-sided Ti / Au interdigitated electrode and the semiconductor;

[0065] S6: Fabrication of the other metal electrode. Using a double overlay and electron beam evaporation process, a Ti / Au interdigitated electrode is fabricated on the opposite side of the electrode obtained in steps S4-S5. The specific process is the same as step S4.

[0066] 3. Working Principle

[0067] The working principle of this example is as follows: Figure 3 As shown. Under reverse bias dark-state conditions, as Figure 3 As shown in (a), a significant conduction band shift (approximately 1.5 eV) is formed between the Al2O3 and Ga2O3 layers, which, combined with the Schottky barrier, constitutes a high barrier, effectively blocking electron transport from the metal electrode to the Ga2O3 layer and suppressing the dark current to an extremely low level. Simultaneously, the ultrathin Al2O3 layer effectively passivates the defect states on the Ga2O3 surface, cutting off the defect-assisted tunneling leakage path. Under reverse bias and deep ultraviolet illumination conditions, such as Figure 3 As shown in (b), the Ga2O3 layer absorbs photons to generate electron-hole pairs. Driven by the built-in electric field, the photogenerated holes drift to the Al2O3 / Ga2O3 heterojunction interface and are captured by deep-level interface traps, forming a localized positive space charge layer. This positive charge layer partially shields the electric field on the metal side, effectively introducing a positive surface potential, significantly reducing the width of the depletion layer on the Ga2O3 side. The geometric compression of the depletion layer greatly shortens the electron tunneling integration path, exponentially enhancing the electron transmission coefficient. Photogenerated electrons are efficiently collected by the metal electrodes through tunneling, forming a high photocurrent. This adaptive carrier transport modulation mechanism of "high resistance in the dark state - low resistance in the light state" in the tunnel junction significantly improves the device's photocurrent-to-signal-noise ratio.

[0068] Example 2

[0069] This example is basically the same as Example 1, except that the ultrathin wide bandgap barrier layer uses HfO2 with a thickness of 3 nm.

[0070] Differences in preparation methods: In step 3, HfO2 thin films were deposited using ALD technology. The precursors were tetra(ethylmethylamino)hafnium (TEMAHf) and water, the deposition temperature was 250°C, and the number of cycles was approximately 30, resulting in an ultrathin HfO2 layer with a thickness of approximately 3 nm.

[0071] Everything else is the same as in Example 1.

[0072] Example 3

[0073] This example is basically the same as Example 1, except that the ultrathin wide bandgap barrier layer uses ZrO2 with a thickness of 3 nm.

[0074] Differences in preparation methods: In step 3, ZrO2 thin films were deposited using ALD technology. The precursors were tetra(ethylmethylamino)zirconium (TEMAZr) and water, the deposition temperature was 250°C, and the number of cycles was approximately 30, resulting in an ultrathin ZrO2 layer with a thickness of approximately 3 nm.

[0075] Everything else is the same as in Example 1.

[0076] Example 4

[0077] This example provides an MSM-type gallium oxide deep ultraviolet photodetector with an Al2O3 / HfO2 stacked composite structure as an ultrathin wide bandgap barrier layer.

[0078] The device structure is the same as in Example 1, except that the ultrathin wide bandgap barrier layer adopts an Al2O3 / HfO2 stacked composite structure, in which an HfO2 layer with a thickness of 2 nm is deposited first as an interface passivation layer, and then an Al2O3 layer with a thickness of 1 nm is deposited as a high barrier tunneling layer, with a total thickness of 3 nm.

[0079] The preparation method is as follows:

[0080] Steps S1 and S2: Same as in Example 1.

[0081] Step S3: Deposition of an ultrathin wide bandgap barrier layer. First, an ultrathin HfO2 layer was deposited on the surface of the β-Ga2O3 film using ALD technology for 20 cycles, with a thickness of approximately 2 nm, under the same deposition conditions as in Example 2. Then, an ultrathin Al2O3 layer was deposited in the same ALD chamber for 10 cycles, with a thickness of approximately 1 nm, under the same deposition conditions as in Example 1. This stacked structure comprehensively utilizes the excellent field-effect passivation capability of HfO2 and the higher barrier height of Al2O3, achieving synergistic optimization of interface quality and tunneling characteristics.

[0082] Step S4: Same as in Example 1.

[0083] Example 5

[0084] 1. Device Structure

[0085] This example provides a bottom-gate TFT gallium oxide deep ultraviolet photodetector based on Al2O3 tunnel junction modulation, such as... Figure 4 As shown in (a), the detector structure includes:

[0086] Substrates 11 and 61: Heavily doped silicon wafers serve as both substrates and gate electrodes, with a thickness of 500 μm.

[0087] High-k oxide gate dielectric layer 71: An Al2O3 layer with a thickness of 50 nm disposed on a silicon substrate.

[0088] Gallium oxide channel layer 21: A β-Ga2O3 thin film with a thickness of 100 nm disposed on the gate dielectric layer.

[0089] Ultrathin wide bandgap barrier layer 31: An ultrathin Al2O3 layer with a thickness of 2 nm is disposed on the gallium oxide channel layer.

[0090] Source electrode 41: A Ti / Au electrode disposed on an ultrathin Al2O3 layer, forming an ohmic contact with the gallium oxide layer.

[0091] Drain electrode 51: A Ti / Au electrode disposed on an ultrathin Al2O3 layer, with a Schottky contact with the gallium oxide layer.

[0092] 2. Preparation method

[0093] Step S1: Substrate preparation. A heavily doped silicon wafer with a resistivity of <0.005 Ω·cm is used as both the substrate and the gate electrode.

[0094] Step S2: Preparation of high-k oxide gate dielectric layer. An Al2O3 layer was deposited on a silicon substrate using ALD technology, with deposition conditions the same as in Step 3 of Example 1, and approximately 500 cycles were performed to obtain an Al2O3 gate dielectric layer with a thickness of approximately 50 nm.

[0095] Step S3: Gallium oxide channel layer growth. A β-Ga2O3 thin film was grown on the Al2O3 gate dielectric layer using MOCVD technology, under the same growth conditions as in Step 2 of Example 1, to obtain a β-Ga2O3 channel layer with a thickness of approximately 100 nm.

[0096] Step S4: Preparation of ultrathin Al2O3 tunnel junction layer. An Al2O3 thin film was deposited on the gallium oxide channel layer using ALD technology. The deposition conditions were the same as in step S3 of Example 1, and the number of cycles was about 20 to obtain an ultrathin Al2O3 layer with a thickness of about 2 nm.

[0097] Step S5: Fabrication of the gate electrode electrical contact region. Using standard photolithography and etching processes, the Al2O3 barrier layer, Ga2O3 channel layer, and Al2O3 gate dielectric layer are completely etched away in a portion of the device, exposing the heavily doped Si gate electrode surface.

[0098] Step S6: Source electrode fabrication. A Ti / Au electrode is fabricated on the surface of the Al2O3 layer using ultraviolet lithography and electron beam evaporation. The specific process is the same as step S4 in Example 1.

[0099] Step S7: Annealing to form ohmic contacts. The sample obtained in step S5 is subjected to a rapid thermal annealing process to achieve ohmic contacts between the source electrode and the semiconductor.

[0100] Step S8: Drain electrode fabrication. A Ti / Au electrode is fabricated at the position corresponding to the source electrode obtained in steps S5 and S6 using a double overlay and electron beam evaporation process. The specific process is the same as in step S5.

[0101] 3. Working Principle

[0102] The working principle of this example is as follows: Figure 3 As shown. Under dark conditions, Figure 3 (a) The Al2O3 tunnel junction layer and the Ga2O3 channel layer form a high potential barrier, effectively preventing carrier injection from the drain electrode into the channel, thus suppressing the off-state dark current of the TFT device to an extremely low level. Under deep ultraviolet light illumination and drain reverse bias conditions ( Figure 3 (b) The Ga2O3 channel layer absorbs photons to generate electron-hole pairs. Driven by the built-in electric field, the photogenerated holes drift to the Al2O3 / Ga2O3 heterojunction interface and are captured by deep-level interface traps, forming a localized positive space charge layer. This positive charge layer enhances the built-in electric field of the drain, significantly thinning the channel depletion layer width on the drain side. This drastically shortens the electron tunneling integration path, exponentially increasing the tunneling probability. The source / drain electrodes efficiently collect photogenerated electrons, generating a high photocurrent. Furthermore, by applying a bias voltage to the gate electrode, the channel carrier concentration and depletion state can be further controlled, enabling sensitive amplification of photoelectric signals and active addressing.

[0103] Example 6

[0104] 1. Device Structure

[0105] This example provides a top-gate TFT gallium oxide deep ultraviolet photodetector based on Al2O3 tunnel junction modulation, such as... Figure 4 As shown in (b), the detector structure includes:

[0106] Substrates 11 and 61: Sapphire substrates with a thickness of 430 μm.

[0107] Gallium oxide channel layer 21: A β-Ga2O3 thin film with a thickness of 100 nm disposed on the gate dielectric layer.

[0108] Ultrathin wide bandgap barrier layer 31: An ultrathin Al2O3 layer with a thickness of 2 nm is disposed on the gallium oxide channel layer.

[0109] Source electrode 41: A Ti / Au electrode disposed on an ultrathin Al2O3 layer, forming an ohmic contact with the gallium oxide layer.

[0110] Drain electrode 51: A Ti / Au electrode disposed on an ultrathin Al2O3 layer, with a Schottky contact with the gallium oxide layer.

[0111] High-k oxide gate dielectric layer 71: An Al2O3 layer with a thickness of 50 nm covering the channel region.

[0112] 2. Preparation method

[0113] Step S1: Substrate cleaning. Same as step 1 in Example 1.

[0114] Step S2: Ga2O3 channel layer growth. A β-Ga2O3 thin film was grown on a sapphire substrate using MOCVD technology, under the same growth conditions as in Step 2 of Example 1, to obtain a Ga2O3 channel layer with a thickness of approximately 50 nm.

[0115] Step S3: Preparation of high-k oxide gate dielectric layer. An Al2O3 layer was deposited on the Ga2O3 channel layer using ALD technology, under the same deposition conditions as in Step S2 of Example 5, with approximately 500 cycles, to obtain an Al2O3 gate dielectric layer with a thickness of approximately 50 nm.

[0116] Step S4: Fabrication of electrical contact areas. Using standard photolithography and etching processes, the Al2O3 gate dielectric layer is completely etched away in a portion of the device, exposing the surface of the gallium oxide channel layer.

[0117] Step S5: Preparation of ultrathin Al2O3 tunnel junction layer. An Al2O3 thin film was deposited on the gallium oxide channel layer using ALD technology. The deposition conditions were the same as in step S3 of Example 1, and the number of cycles was about 20 to obtain an ultrathin Al2O3 layer with a thickness of about 2 nm.

[0118] Step S6: Source electrode fabrication. A Ti / Au (30 nm / 80 nm) metal layer is deposited in a specific region on the exposed gallium oxide channel layer surface using photolithography and electron beam evaporation. The photoresist is then removed via a lift-off process to form the source electrode.

[0119] Step S7: Annealing to form ohmic contacts. The sample obtained in step S5 is subjected to a rapid thermal annealing process to achieve ohmic contacts between the source electrode and the semiconductor;

[0120] Step S8: Drain and gate electrode fabrication. Using a double overlay and electron beam evaporation process, a Ti / Au drain electrode is fabricated at the position corresponding to the source electrode obtained in steps S6 and S7. A Ti / Au gate electrode is fabricated at a specific position in the unetched gate dielectric layer. The specific process is the same as in step S6.

[0121] Example 7

[0122] 1. Device Structure

[0123] This example provides a PN junction gallium oxide deep ultraviolet photodetector with nickel oxide (NiO) as the p-type semiconductor layer and Al2O3 as an ultrathin wide bandgap barrier layer.

[0124] like Figure 5 As shown in (a), the detector structure includes:

[0125] Substrate 12: Sapphire substrate, double-sided polished, with a thickness of 430 μm.

[0126] n-type gallium oxide epitaxial layer 22: An N-type β-Ga₂O₃ epitaxial layer disposed on the substrate, with a thickness of 500 nm and a doping concentration of 1×10⁻⁶. 17 cm -3 .

[0127] Ultrathin wide bandgap barrier layer 32: An ultrathin Al2O3 layer with a thickness of 2 nm is disposed on an N-type gallium oxide layer.

[0128] p-type semiconductor layer 82: A p-type nickel oxide layer (NiO) with a thickness of 100 nm is disposed on an Al2O3 layer.

[0129] n-type electrode 42: An N-type electrode that forms an ohmic contact with an N-type gallium oxide layer, made of Ti / Au, with a Ti thickness of 30 nm and an Au thickness of 100 nm.

[0130] p-type electrode 52: A p-type electrode that forms an ohmic contact with a p-type NiO layer. The material is Ni / Au, with a Ni thickness of 30 nm and an Au thickness of 100 nm.

[0131] 2. Preparation method

[0132] Step S1: Substrate cleaning. Same as Example 1.

[0133] Step S2: n-type gallium oxide epitaxial layer growth. A Si-doped β-Ga₂O₃ thin film was epitaxially grown on a sapphire substrate using MOCVD. In MOCVD, silane (SiH₄) was used as the n-type dopant source. A film with a thickness of approximately 500 nm and a doping concentration of approximately 1 × 10⁻⁶ was obtained. 17 cm -3 n-type β-Ga2O3 thin film.

[0134] Step S3: Deposition of an ultrathin wide bandgap barrier layer. An ultrathin Al2O3 layer was deposited on the surface of an n-type β-Ga2O3 film using ALD technology. TMA and H2O were used as precursors, the deposition temperature was 200-300℃, and the deposition cycle was 20 cycles, resulting in an Al2O3 film with a thickness of approximately 2 nm.

[0135] Step S4: p-type semiconductor layer deposition. A NiO thin film is deposited on the surface of the Al2O3 layer using magnetron sputtering. The magnetron sputtering conditions are as follows: NiO ceramic target as the target material, sputtering power 100-150 W, Ar / O2 mixed atmosphere (O2 partial pressure 30%-50%), substrate temperature 300-400℃, to obtain a p-type NiO thin film with a thickness of approximately 150 nm.

[0136] Step S5: n-type electrode fabrication. Using standard photolithography and etching processes, a portion of the NiO and Al2O3 layers are etched away on one side of the device to expose the n-type gallium oxide surface. Then, an electron beam evaporation process is used to deposit a Ti / Au (30 nm / 80 nm) metal layer in this exposed area. The photoresist is removed using a lift-off process to form the n-type contact electrode.

[0137] Step S6: p-type electrode fabrication. A p-type electrode pattern is defined on the surface of the NiO layer using standard photolithography. Ni / Au (20 nm / 80 nm) metal layers are deposited using electron beam evaporation. A p-type contact electrode is then formed via a lift-off process.

[0138] Step S7: Rapidly heat anneal at 400-500℃ for 5 minutes in a N2 atmosphere to achieve ohmic contact between the n-type and p-type electrodes.

[0139] 3. Working Principle

[0140] The working principle of this embodiment is as follows: Figure 6 As shown. Under reverse bias dark-state conditions, as Figure 6 As shown in (a), the Al2O3 layer forms a high potential barrier between n-type Ga2O3 and p-type NiO, effectively passivating interface defect states and cutting off defect-assisted tunneling leakage channels, thus suppressing dark current to an extremely low level. Under reverse bias and deep ultraviolet illumination conditions, as shown in (a), Figure 6As shown in (b), the Ga2O3 layer absorbs photons to generate electron-hole pairs. Driven by the built-in electric field, the photogenerated holes drift to the Al2O3 / Ga2O3 heterojunction interface and are captured by deep-level interface traps, forming a localized positive space charge layer. This positive charge layer partially shields the P-region electric field, effectively introducing a positive interface potential, enhancing the built-in field, making the PN junction bandgap more tilted, reducing the effective barrier width, significantly shortening the electron tunneling integral path, and exponentially increasing the tunneling probability. Photogenerated carriers tunnel through efficiently, forming a high photocurrent. This adaptive carrier transport modulation mechanism of "high resistance in the dark state to low resistance in the light state" significantly improves the device's photocurrent-to-signal-noise ratio.

[0141] Example 8

[0142] This embodiment is basically the same as Embodiment 7, except that: the ultrathin wide bandgap barrier layer uses HfO2 with a thickness of 3nm; the P-type semiconductor layer uses copper aluminum oxide (CuAlO2) with a thickness of 100nm.

[0143] Differences in preparation methods: In step S3, HfO2 thin films are deposited using ALD technology, with approximately 30 cycles. In step S4, CuAlO2 thin films are deposited using radio frequency magnetron sputtering technology, with a CuAlO2 ceramic target, an Ar / O2 sputtering atmosphere (volume ratio 3:1), a sputtering power of 120 W, a substrate temperature of 400°C, and a deposition time of 20 min, resulting in a P-type CuAlO2 layer with a thickness of approximately 80 nm.

[0144] Copper aluminum oxide is a wide bandgap p-type oxide semiconductor with excellent transparency, conductivity, and chemical stability. It forms a heterojunction with N-type Ga2O3 with good bandgap matching.

[0145] Example 9

[0146] This embodiment is basically the same as Embodiment 7, except that: the ultrathin wide bandgap barrier layer uses HfO2 with a thickness of 3nm; the P-type semiconductor layer uses tin oxide (SnO) with a thickness of 100nm.

[0147] Differences in preparation methods: In step S3, HfO2 thin films are deposited using ALD technology. In step S4, SnO thin films are prepared using pulsed laser deposition (PLD) technology, with a SnO ceramic target, a laser wavelength of 248 nm, and an energy density of 2 J / cm². 2 A P-type SnO layer with a thickness of approximately 100 nm was obtained by using a substrate temperature of 300°C, an oxygen pressure of 10 mTorr, and a deposition time of 15 min.

[0148] Example 10

[0149] 1. Device Structure

[0150] This embodiment is basically the same as Embodiment Seven, except that: a gallium oxide substrate is used; the P-type semiconductor layer is cuprous oxide (Cu₂O) with a thickness of 120 nm; and an out-of-plane electrode is used, with the N-type electrode fabricated on the back side of the substrate. Figure 5 As shown in (b), the detector structure includes:

[0151] Substrate 12: Gallium oxide single crystal substrate, double-sided polished, with a thickness of 200 μm.

[0152] n-type gallium oxide epitaxial layer 22: An N-type β-Ga₂O₃ epitaxial layer disposed on the substrate, with a thickness of 500 nm and a doping concentration of 1×10⁻⁶. 17 cm -3 .

[0153] Ultrathin wide bandgap barrier layer 32: An ultrathin Al2O3 layer with a thickness of 2 nm is disposed on an N-type gallium oxide layer.

[0154] p-type semiconductor layer 82: A p-type Cu2O thin film disposed on an Al2O3 layer with a thickness of 120 nm.

[0155] n-type electrode 42: An N-type electrode that forms an ohmic contact with an N-type gallium oxide layer, made of Ti / Au, with a Ti thickness of 30 nm and an Au thickness of 100 nm.

[0156] p-type electrode 52: A p-type electrode that forms an ohmic contact with the p-type Cu2O layer. The material is Ni / Au, with a Ni thickness of 30 nm and an Au thickness of 100 nm.

[0157] 2. Preparation method

[0158] Differences in preparation methods: In step S1, a gallium oxide single-crystal substrate with a thickness of 200 μm is used. In step 3, a ZrO2 thin film is deposited using ALD technology, with approximately 40 cycles. In step S4, a Cu2O thin film is prepared using electrochemical deposition: copper nitrate aqueous solution is used as the electrolyte, pH=5.5, deposition potential is -0.4 V (relative to a saturated calomel electrode), deposition temperature is 60°C, and deposition time is 30 min, resulting in a p-type Cu2O layer with a thickness of approximately 120 nm. In step S5, an electron beam evaporation technique is used to deposit a Ti / Au (30 nm / 80 nm) metal layer on the back side of the gallium oxide substrate to form an n-type contact electrode.

[0159] Performance testing

[0160] The performance of the deep ultraviolet photodetector prepared in the above embodiments was tested under the following conditions:

[0161] (1) Dark current test: Under no light conditions, the current value of the device under different bias voltages is measured using a semiconductor parameter analyzer.

[0162] (2) Photocurrent test: Deep ultraviolet LED (wavelength 254 nm) was used as the light source to measure the photocurrent of the device under different light intensity and bias conditions.

[0163] (3) Calculation of photocurrent to dark current ratio: Photocurrent to dark current ratio = Photocurrent value / Dark current value.

[0164] Test results show that the gallium oxide-based deep ultraviolet photodetectors prepared in each embodiment of this application all achieve ultra-low dark current (<10). -11 (on the order of A) and a significantly improved photodarkening ratio (>10). 6 The specific performance varies slightly depending on the type and thickness of the wide bandgap barrier layer material and the choice of P-type material (on the order of magnitude). Devices using HfO2 tunnel junctions exhibit good interface passivation; devices using Al2O3 tunnel junctions demonstrate superior dark current suppression due to their higher bandgap; and devices using multilayer tunnel junctions show better overall performance. A variety of P-type semiconductor materials are well compatible with tunnel junction structures, providing ample options for device optimization. Figure 7 (a) and (b) show a performance comparison between the conventional MSM device and the Al2O3 tunnel junction modulation device in Example 1, where the power density of the deep ultraviolet LED (wavelength 254 nm) is approximately 20 μW / cm². 2 The dark current of traditional MSM devices is 10. -11 The order of magnitude, with a photocurrent-to-dark-current ratio of 10. 5 The order of magnitude; while devices modulated by tunnel junctions exhibit 10 -13 Dark current on the order of magnitude, and 10 7 The ratio of light to dark current is on the order of magnitude.

[0165] Regarding the passivation effect of ultrathin wide bandgap dielectric layers on gallium oxide surface defects, this application demonstrates and verifies this effect through the following two complementary methods:

[0166] (1) Direct testing method: high frequency-quasi-static capacitance-voltage (CV) method

[0167] The capacitance of Al2O3 / β-Ga2O3(010) tunnel heterojunction was measured using the high-frequency-quasi-static CV method reported in the literature, and the interface density of states D at the Al2O3 / β-Ga2O3 heterojunction interface was extracted. it The D10 of the Al2O3 / β-Ga2O3(010) interface was experimentally measured. it The value is 1.6 × 10 11 cm -2 eV -1The energy range is a shallow energy level region of 0.8–0.1 eV below the conduction band bottom. In contrast, the interface state density of a β-Ga2O3 substrate without an Al2O3 passivation layer is 1.9 × 10⁻⁶. 12 cm -2 eV -1 D is approximately one order of magnitude it The reduction directly confirms the effective passivation effect of the ultrathin Al2O3 layer on surface defect states and dangling bonds of gallium oxide.

[0168] (2) Indirect electrical verification: significant reduction in dark current

[0169] This application can still indirectly demonstrate the interface passivation effect through the test results of dark current and photo-dark current ratio. Traditional Ga2O3 MSM photodetectors suffer from excessively high dark current due to the lack of an effective barrier between electrodes, and the surface state and dislocation density exacerbate the leakage current. After introducing an ultrathin Al2O3 insulating layer, the device dark current is significantly reduced by 1-2 orders of magnitude. Such a significant dark current suppression effect can only be reasonably explained from the perspective of effective passivation of interface defect states: the dangling bonds on the gallium oxide surface are saturated by the ultrathin Al2O3 layer, the defect-assisted tunneling channels are greatly suppressed, and the leakage current under reverse bias is significantly reduced; at the same time, the Al2O3 layer forms a wide bandgap energy barrier to suppress electron leakage.

[0170] The tunnel junction-controlled gallium oxide deep ultraviolet photodetector and its fabrication method proposed in this application have the characteristics of simple structure, good process compatibility and excellent performance. They can be widely used in fields such as flame early warning systems, space communication, ozone layer monitoring, high voltage corona detection, biochemical analysis, ultraviolet imaging arrays and portable ultraviolet detection equipment, and have good industrial application prospects and commercial value.

[0171] The above description, in conjunction with specific embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. Those skilled in the art to which this application pertains can make several simple deductions or substitutions without departing from the concept of this application.

Claims

1. A gallium oxide deep ultraviolet photodetector, characterized in that: This includes adding an ultrathin wide bandgap barrier layer between the gallium oxide layer and the electrode, or between the N-type gallium oxide layer and the P-type semiconductor layer; The ultrathin wide bandgap barrier layer is formed by at least one material selected from aluminum oxide, zirconium oxide, hafnium oxide, and aluminum nitride, forming a single-layer or multi-layer stacked structure.

2. The gallium oxide deep ultraviolet photodetector according to claim 1, characterized in that: The thickness of the ultrathin wide bandgap barrier layer is 1-20 nm.

3. The gallium oxide deep ultraviolet photodetector according to claim 1, characterized in that: The gallium oxide layer or the N-type gallium oxide layer is β-phase gallium oxide with a thickness of 10 nm-10 μm.

4. The gallium oxide deep ultraviolet photodetector according to any one of claims 1-3, characterized in that: The gallium oxide deep ultraviolet photodetector is at least one of the following: MSM type detector, bottom-gate type TFT detector, top-gate type TFT detector, and PN junction type detector.

5. The gallium oxide deep ultraviolet photodetector according to claim 4, characterized in that: The MSM-type detector includes a substrate, a gallium oxide layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the gallium oxide layer, and interdigitated electrodes fabricated on the ultrathin wide bandgap barrier layer.

6. The gallium oxide deep ultraviolet photodetector according to claim 4, characterized in that: The bottom-gate TFT detector includes a substrate, a gate electrode disposed on the substrate, a gate dielectric layer disposed on the gate electrode, a gallium oxide layer disposed on the gate dielectric layer, an ultrathin wide bandgap barrier layer disposed on the gallium oxide layer, and a source electrode and a drain electrode disposed on the ultrathin wide bandgap barrier layer.

7. The gallium oxide deep ultraviolet photodetector according to claim 4, characterized in that: The top-gate TFT detector includes a substrate, a gallium oxide layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the gallium oxide layer, a source electrode, a drain electrode, and a gate dielectric layer disposed on the ultrathin wide bandgap barrier layer, and a gate electrode disposed on the gate dielectric layer.

8. The gallium oxide deep ultraviolet photodetector according to claim 4, characterized in that: The PN junction detector includes a substrate, an N-type gallium oxide layer disposed on the substrate, an ultrathin wide bandgap barrier layer disposed on the N-type gallium oxide layer, a P-type semiconductor layer disposed on the ultrathin wide bandgap barrier layer, and an N-type electrode and a P-type electrode that form ohmic contacts with the N-type gallium oxide layer and the P-type semiconductor layer, respectively. Optionally, the P-type semiconductor layer is formed of at least one material selected from nickel oxide, copper aluminum oxide, cuprous oxide, copper gallium oxide, copper chromium oxide, nickel cobalt oxide, tin oxide, cuprous sulfide, cuprous iodide, p-type gallium nitride, p-type silicon carbide, p-type aluminum nitride, and p-type diamond.

9. The method for fabricating a gallium oxide deep ultraviolet photodetector according to any one of claims 1-8, characterized in that: This includes using atomic layer deposition technology to prepare an ultrathin wide bandgap barrier layer on the gallium oxide layer or the N-type gallium oxide layer.

10. The preparation method according to claim 9, characterized in that: The deposition temperature for the atomic layer deposition is 80-300℃.

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