Embedded plasma element ultraviolet photoelectric detector and preparation method thereof

Abstract

The invention discloses an embedded plasma element ultraviolet photoelectric detector and a preparation method thereof, and mainly solves the problem that the existing gallium oxide-based ultraviolet photoelectric detector cannot give consideration to higher response speed while obtaining high light response. The device comprises a substrate, a buffer layer, a bottom electrode, a photosensitive layer and a top electrode. The photosensitive layer adopts a multi-layer material composite structure which sequentially comprises a strong N-type wide bandgap semiconductor beta-Ga2O3 layer, an Al plasma element layer, a weak N-type wide bandgap semiconductor beta-Ga2O3 layer and an Al plasma element layer from bottom to top, so that an ultraviolet resonance effect is formed, and a local electric field of the photosensitive layer is enhanced; the bottom electrode is located on one side of the strong N-type wide bandgap semiconductor beta-Ga2O3 layer and covers the Al plasma element layer so as to extract photon-generated carriers in the photosensitive layer and improve the transport efficiency of the carriers, the photoelectric gain, the responsivity and the detectivity of the detector can be improved, the response speed can be increased, and the detection efficiency of the detector can be improved. The method can be used for low-noise ultraviolet light band single photon detection and ultraviolet communication.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to a photodetector and its fabrication method, which can be used for low-noise deep ultraviolet single-photon detection and optoelectronic communication. Background Technology

[0002] Photodetectors are devices that convert optical signals into electrical signals, and are widely used in optical communication, optical storage, and optical information processing. In the electromagnetic spectrum, ultraviolet light refers to micrometer-level radiation with wavelengths from 10 nm to 400 nm, located between the violet end of the visible light spectrum and X-rays. Due to its high energy and lack of visual perception, it can be used for sterilization and ultraviolet communication. Solar-blind ultraviolet radiation is located in the 220–280 nm range. Sunlight in this band is strongly absorbed by the ozone layer when passing through the atmosphere and is almost non-existent in the near-Earth atmosphere. In this environmental context, detecting or imaging ultraviolet radiation in this band is unaffected by sunlight interference and has a clean background, resulting in a higher signal-to-noise ratio, lower false alarm rate, and unique target recognition advantages. Therefore, solar-blind ultraviolet detection technology has significant applications in space-based, airborne, and shipborne early warning systems, and also shows important prospects in fire early warning and engine monitoring, high-voltage corona detection and power safety, sterilization and disinfection monitoring, solar-blind ultraviolet communication, and biochemical reaction monitoring.

[0003] Currently, practical solar-blind ultraviolet detectors mainly consist of photomultiplier tubes (PMTs) and silicon-based ultraviolet photodiodes (SUVs). While PMTs offer high sensitivity, they require high operating voltages and vacuum packaging, resulting in large size, low efficiency, susceptibility to damage, and high cost, hindering device miniaturization and safety improvements. Furthermore, due to the narrow bandgap of Si, SUVs exhibit a more pronounced response in the visible / infrared bands, necessitating filters to confine the response to the solar-blind band, undoubtedly increasing system size and cost.

[0004] To develop filterless, compact solar-blind ultraviolet detectors, various wide-bandgap semiconductor materials, such as diamond, AlGaN, MgZnO, and Ga2O3, have been extensively studied. Diamond's bandgap is as high as 5.5 eV, making it sensitive only to deep ultraviolet light with wavelengths shorter than 225 nm, significantly reducing its detection efficiency for solar-blind ultraviolet light. Alloy materials, represented by AlGaN and MgZnO, can have their bandgap adjusted by changing the proportions of the metal elements, thus enabling light detection in different wavelength bands. For AlGaN, by controlling the composition ratio of Al and Ga, the bandgap can be adjusted within the range of 3.39 eV (GaN bandgap) to 6.2 eV (AlN bandgap), covering almost the entire ultraviolet region. It is the most mature material in the development of wide-bandgap semiconductor solar-blind ultraviolet detectors, and focal plane array imaging detection has already been achieved. MgZnO materials, by adjusting the Mg composition, can achieve a bandgap between that of ZnO (3.37 eV) and MgO (7.8 eV), thus also possessing the potential for solar-blind ultraviolet detection. However, the growth of AlGaN and MgZnO mostly utilizes metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) techniques, which involve large and expensive equipment, complex epitaxial processes, and high temperatures (especially for AlGaN materials, where growth temperatures typically exceed 1000 °C), increasing the cost of thin film fabrication.

[0005] Ga2O3, as a wide bandgap oxide semiconductor material, has a bandgap of 4.9 eV. Its photoresponse peak falls precisely in the solar-blind ultraviolet band, and its absorption coefficient near the absorption edge is as high as 10. 5 cm -1 Ga2O3 is a natural solar-blind ultraviolet (UV) detector material that does not require bandgap modulation. Ga2O3 is inexpensive, exhibits excellent thermal and chemical stability, and can withstand strong electric fields up to 8 MV / cm, enabling its application in harsh conditions. In recent years, Ga2O3-based UV detectors have become a major research hotspot in the semiconductor field. Short-range ordered, wide-bandgap amorphous Ga2O3 thin films can be fabricated at low temperatures on silicon, glass, and even plastic substrates using methods such as magnetron sputtering and atomic layer deposition, resulting in simple and inexpensive processes. Furthermore, high-temperature annealing can transform amorphous Ga2O3 thin films into polycrystalline Ga2O3 thin films, giving polycrystalline Ga2O3-based UV detectors solar-blind UV response characteristics comparable to single-crystal films.

[0006] Patent document CN120456625A discloses a vertical-structure ultraviolet photodetector, which forms a hole transport layer by spin-coating a nickel oxide solution onto a β-Ga₂O₃ single crystal and then annealing it. However, the nickel oxide film formed by spin-coating a nickel oxide solution onto a β-Ga₂O₃ single crystal and then annealing is an amorphous film, and due to lattice mismatch, the crystal quality of the prepared nickel oxide film is not high. In addition, the instability of the spin-coating process leads to uneven film thickness. These factors all result in low carrier mobility, and defects within the crystal promote recombination of photogenerated carriers. Therefore, the responsivity and response speed of the prepared photodetector are severely affected, resulting in performance degradation.

[0007] Patent document CN120640822A discloses an MSM-structured ultraviolet photodetector based on p-Si / Ga2O3 / ZnO. This MSM-structured ultraviolet photodetector is fabricated by sputtering Ga2O3 and ZnO thin films onto a double-sided polished p-Si substrate using RF magnetron sputtering technology. However, due to the low lattice matching between the p-Si substrate and Ga2O3, the sputtered Ga2O3 film exhibits poor crystal quality and numerous crystal defects. Furthermore, the magnetron-sputtered film is amorphous, leading to reduced carrier mobility. Additionally, because this device is a parallel device using an MSM structure, it does not fully utilize the heterojunction structure, thus limiting the ability to further improve the device's responsivity and response rate, ultimately restricting its performance. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of the prior art by proposing an embedded plasma-based ultraviolet photodetector and its fabrication method, so that the gallium oxide-based ultraviolet photodetector can achieve high photoelectric gain while also having a fast response speed and a higher specific detectivity, thereby improving device performance.

[0009] To achieve the above objectives, the technical solution of the present invention includes the following:

[0010] 1. An embedded plasma-based ultraviolet photodetector, comprising: a substrate, a buffer layer, a photosensitive layer, a bottom electrode, and a top electrode, characterized in that:

[0011] The photosensitive layer adopts a multilayer semiconductor material composite structure consisting of a strong N-type wide bandgap semiconductor β-Ga2O3 layer, an Al plasma matrix layer, a weak N-type wide bandgap semiconductor β-Ga2O3 layer, and an Al plasma matrix layer from top to bottom, so that the device has light response in the ultraviolet band and a plasma matrix layer, thereby improving the responsivity, detectivity, and response speed of the photodetector.

[0012] The bottom electrode is located on one side of the strong N-type wide bandgap semiconductor β-Ga2O3 layer and covers the Al plasma matrix layer, thereby extracting photogenerated carriers from the photosensitive layer, improving the carrier transport efficiency, and further improving the response speed.

[0013] Preferably, the substrate is a single-sided polished sapphire substrate with a thickness of 0.8~1mm and a size of 1cm×1cm;

[0014] The buffer layer is a strong N-type β-Ga2O3 thin film, which is located on the substrate and has a thickness of 60nm~90nm. Its size and shape are consistent with the substrate.

[0015] Preferably, the strong N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer is located above the buffer layer, has a thickness of 200nm~300nm, and its size and shape are consistent with the substrate, with an electron concentration of 1×10⁻⁶. 15 cm -3 The Al plasma-based layer has a thickness of 5 nm to 10 nm and its size and shape are consistent with the substrate; the weak N-type wide bandgap semiconductor β-Ga₂O₃ layer has a thickness of 200 nm to 300 nm, a size of 0.7 cm × 1 cm, and an electron concentration of 1 × 10⁻⁶. 13 cm -3 The Al plasma-based layer has a thickness of 20nm~30nm and its size and shape are consistent with the weak N-type wide bandgap semiconductor β-Ga2O3 layer.

[0016] Preferably, the bottom electrode has a thickness of 50nm~100nm, is strip-shaped, and has a size of 20~40μm×200~250μm. It is located on the edge of the top Al plasma matrix layer away from the top electrode and forms a Schottky contact with the strong N-type β-Ga2O3 thin film, and is in contact with the Al plasma matrix. The top electrode has a thickness of 50nm~100nm, is finger-shaped, and has a finger length of 150~200μm, a finger width of 50~80μm, and a finger spacing of 50~80μm. It is located on top of the weak N-type β-Ga2O3 epitaxial layer and the Al plasma matrix layer, and forms an ohmic contact with the weak N-type β-Ga2O3 epitaxial layer, and is in contact with the Al plasma matrix. Both the bottom electrode and the top electrode are made of Ti / Au or Cr / Au metal materials.

[0017] 2. A method for fabricating an embedded plasma-based ultraviolet photodetector, characterized by comprising:

[0018] S1) Select a single-sided polished sapphire substrate, clean it, and then dry it with nitrogen.

[0019] S2) A gallium oxide film with a thickness of 60nm~90nm was epitaxially grown on the polished surface of a sapphire substrate using RF magnetron sputtering, and then annealed in a vacuum to crystallize it into a β-Ga2O3 buffer layer.

[0020] S3) A photosensitive layer was fabricated on a β-Ga2O3 buffer layer using RF magnetron sputtering and vacuum thermal evaporation equipment;

[0021] S4) Using a vacuum thermal evaporation equipment and a bottom electrode mask, a 50nm~100nm Ti / Au bottom electrode is prepared at the top edge of the plasma matrix layer;

[0022] S5) Using a vacuum thermal evaporation equipment and a top electrode mask, a 50nm~100nm thick Ti / Au top electrode is prepared on the top of the plasma matrix layer at the end away from the bottom electrode to complete the fabrication of the photodetector.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] Firstly, because the photosensitive layer of this invention is composed of a combination of multilayer semiconductor materials and nanoparticles, under deep ultraviolet light irradiation, the deep ultraviolet light drives the free electrons on the surface of the Al nanoparticles attached to the Ga2O3 film to move collectively, causing the electron cloud to deviate from the atomic nucleus. At this time, the Coulomb force between the electron cloud and the atomic nucleus exerts an attractive force on the free electrons, attracting the electron cloud back to its original position. Finally, the action of these two forces causes the free electrons to oscillate back and forth within an equilibrium region. This oscillation frequency is consistent with the frequency of ultraviolet light, producing a resonance effect that enhances the nearby electric field, improves the transport efficiency of charge carriers, and thus improves the response speed of the device.

[0025] Secondly, since the photosensitive layer of this invention uses two Ga2O3 thin films with different electron concentrations to form a vertical structure device with an n-homogeneous junction, it can generate a large number of photogenerated carriers under ultraviolet light irradiation. Furthermore, the electric field promotes the separation of photogenerated carriers, which reduces the recombination probability of photogenerated carriers in the device, increases the lifetime of photogenerated carriers in the device, and improves the photoconductivity gain and responsivity of the device.

[0026] Thirdly, since the bottom electrode of this invention is located on one side of the strong N-type wide bandgap semiconductor β-Ga2O3 layer and is covered on the Al plasma matrix layer, when irradiated by ultraviolet light, the Al nanoparticles at the bottom electrode will also undergo a resonance effect to accelerate the extraction of photogenerated carriers in the photosensitive layer, improve the carrier transport efficiency, and further improve the response speed.

[0027] Fourth, this invention improves the lattice matching degree between the sapphire substrate and β-Ga2O3 by preparing a strong N-type β-Ga2O3 thin film as a buffer layer on the sapphire substrate and then preparing a photosensitive layer on the buffer layer. This results in a lower crystal defect concentration, a wider bandgap, and better solar blindness of the Ga2O3 thin film prepared on the buffer layer with a higher lattice matching degree. This better crystal quality can make the prepared photodetector have lower noise and achieve a higher specific detectivity. Attached Figure Description

[0028] Figure 1 A schematic diagram of the structure of the embedded plasma-based ultraviolet photodetector of the present invention;

[0029] Figure 2 This invention is made Figure 1 A schematic diagram of the ultraviolet photodetector process. Detailed Implementation

[0030] To more accurately describe the implementation of the present invention, the present invention will be fully described and explained below in conjunction with the accompanying drawings and embodiments.

[0031] Reference Figure 1 The embedded plasma-based ultraviolet photodetector in this example includes a substrate 1, a buffer layer 2, a photosensitive layer 3, a bottom electrode 4, and a top electrode 5, wherein:

[0032] The substrate 1 is a single-sided polished sapphire substrate with a thickness of 0.8mm to 1mm and a size of 1cm × 1cm.

[0033] The buffer layer 2 is a strong N-type β-Ga2O3 thin film, which is located on the substrate and has a thickness of 60nm~90nm. Its size and shape are the same as those of the substrate 1.

[0034] The photosensitive layer 3, located above the buffer layer 2, employs a composite structure of two semiconductor thin films and two Al plasma matrix layers. Specifically, from top to bottom, it consists of a strong N-type wide bandgap semiconductor β-Ga₂O₃ layer 31, an Al plasma matrix layer 32, a weak N-type wide bandgap semiconductor β-Ga₂O₃ layer 33, and an Al plasma matrix layer 34. The strong N-type wide bandgap semiconductor β-Ga₂O₃ epitaxial layer 31 has a thickness of 200 nm to 300 nm and its size and shape are consistent with the substrate 1. The Al plasma matrix layer 32 has a thickness of 5 nm to 10 nm and its size and shape are consistent with the substrate 1. The weak N-type wide bandgap semiconductor β-Ga₂O₃ layer 33 has a thickness of 200 nm to 300 nm and a size of 0.7 cm × 1 cm. The Al plasma matrix layer 34 has a thickness of 20 nm to 30 nm and its size and shape are consistent with the weak N-type wide bandgap semiconductor β-Ga₂O₃ layer 33.

[0035] The bottom electrode 4 is made of Ti / Au metallic material and is located in the same layer as the strong N-type wide bandgap semiconductor β-Ga2O3 layer 33. Its thickness is 50nm~100nm, its shape is strip-shaped, and its size is 20~40μm×200~250μm. It is located on the edge of the top Al plasma matrix layer 32 away from the top electrode 5, forming an ohmic contact with the strong N-type β-Ga2O3 thin film and contacting the Al plasma matrix.

[0036] The top electrode 5 is made of metallic material Ti / Au with a thickness of 50nm~100nm. It is finger-shaped with a finger length of 150~200μm, a finger width of 50~80μm, and a finger spacing of 50~80μm. It is located on top of the weak N-type β-Ga2O3 epitaxial layer 33 and the Al plasma matrix layer 34, and forms an ohmic contact with the weak N-type β-Ga2O3 epitaxial layer 33 and a contact with the Al plasma matrix.

[0037] Reference Figure 2 This invention provides three embodiments for fabricating embedded plasma-based ultraviolet photodetectors:

[0038] Example 1: Fabrication of an embedded plasma-based ultraviolet photodetector with a substrate thickness of 0.9 mm, a buffer layer thickness of 80 nm, a strong N-type β-Ga2O3 epitaxial layer thickness of 280 nm, an intermediate Al film thickness of 7 nm, a weak N-type β-Ga2O3 epitaxial layer thickness of 280 nm, a top Al film thickness of 20 nm, a bottom electrode thickness of 70 nm and a size of 30 μm × 230 μm, a top electrode thickness of 70 nm, an interdigitated finger length of 170 μm, a finger width of 65 μm, an interdigitated finger spacing of 65 μm, and an electrode material of Ti / Au.

[0039] Step 1: Clean the substrate and prepare a buffer layer.

[0040] 1.1) Select a single-sided polished sapphire substrate with a thickness of 0.9 mm and a size of 1 cm × 1 cm, and heat it separately in acetone.

[0041] Ultrasonic cleaning for 15 minutes each in anhydrous ethanol and deionized water is used to remove surface impurities. After cleaning, the surface is dried with a nitrogen gun for later use.

[0042] 1.2) Set the substrate temperature to room temperature and the chamber vacuum level to 7 × 10⁻⁶. -4 Under the following process conditions: Pa, sputtering atmosphere is argon, argon flow rate is 50 sccm, sputtering power is 140 W, working pressure is 1.2 Pa, target material is gallium oxide target, substrate tray rotation speed is 12 r / min, and growth time is about 17 min, a gallium oxide thin film with the same shape and size as the substrate and a thickness of 80 nm is fabricated on the substrate using RF magnetron sputtering.

[0043] 1.3) Set the temperature to 800℃ and the time to 60 minutes, and anneal the gallium oxide film under vacuum conditions in the furnace tube to obtain a strong N-type wide bandgap semiconductor β-Ga2O3 buffer layer.

[0044] Step 2: Prepare a strong N-type β-Ga2O3 epitaxial layer on the buffer layer.

[0045] 2.1) Set the substrate temperature to room temperature and the chamber vacuum level to 7 × 10⁻⁶. -4 Under the following process conditions: Pa, sputtering atmosphere is argon, argon flow rate is 50 sccm, sputtering power is 140 W, working pressure is 1.2 Pa, target material is gallium oxide target, substrate tray rotation speed is 12 r / min, and growth time is about 45 min, a gallium oxide thin film with the same shape and size as the substrate and a thickness of 280 nm is prepared on the buffer layer by RF magnetron sputtering.

[0046] 2.2) Set the temperature to 800℃ and the time to 60 minutes, and anneal the gallium oxide film under vacuum conditions in the furnace tube to obtain a strong N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer.

[0047] Step 3: Prepare Al plasma units on a strong N-type β-Ga2O3 epitaxial layer.

[0048] 3.1) Set the evaporation current to 95A, the evaporation rate to 0.6nm / s, and the chamber vacuum to 4×10⁻⁶. -4 Under the following process conditions: Pa, tray rotation speed 14 r / min, raw material is high-purity Al metal particles with a purity of 5N and a particle size of approximately 1 mm, a vacuum thermal evaporation device is used to deposit an Al thin film with a thickness of 7 nm on top of a strong N-type β-Ga2O3 epitaxial layer, with the same size and shape as the substrate.

[0049] 3.2) Set the temperature to 500℃ and the time to 60 minutes, and anneal the Al film under an argon atmosphere in the furnace tube to obtain Al nanoparticles.

[0050] Step 4: Prepare a weakly N-type β-Ga2O3 epitaxial layer on Al plasma basis.

[0051] 4.1) Set the substrate temperature to room temperature and the chamber vacuum level to 7 × 10⁻⁶. -4The process conditions were as follows: sputtering atmosphere of argon and oxygen, argon flow rate of 47 sccm, oxygen flow rate of 3 sccm, sputtering power of 140 W, working pressure of 1.2 Pa, target material of gallium oxide, substrate tray rotation speed of 12 r / min, and growth time of approximately 45 min. The RF magnetron sputtering method was used. First, a weak N-type β-Ga₂O₃ epitaxial layer mask was deposited on an Al plasma matrix. Then, a gallium oxide thin film with a thickness of 280 nm was sputtered at the reserved vacancy positions on the mask.

[0052] 4.2) Set the temperature to 800℃ and the time to 60 minutes, and anneal the gallium oxide thin film under air atmosphere conditions in the furnace tube to obtain a weak N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer.

[0053] Step 5: Prepare Al plasma units on a weakly N-type β-Ga2O3 epitaxial layer.

[0054] 5.1) Set the evaporation current to 95A, the evaporation rate to 0.6nm / s, and the chamber vacuum to 4×10⁻⁶. -4 Under the following process conditions: Pa, tray rotation speed 14 r / min, raw material is high-purity Al metal particles with a purity of 5N and a particle size of approximately 1 mm, a vacuum thermal evaporation device is used to deposit an Al thin film with a thickness of 20 nm on top of a strong N-type β-Ga2O3 epitaxial layer, with the same size and shape as the substrate.

[0055] 5.2) Set the temperature to 500℃ and the time to 60 minutes, and anneal the Al film under an argon atmosphere in the furnace tube to obtain Al nanoparticles.

[0056] Step 6: Fabricate the bottom electrode on the strong N-type β-Ga2O3 epitaxial layer.

[0057] 6.1) Set the evaporation current to 125A, the evaporation rate to 1.5nm / s, and the chamber vacuum to 4×10⁻⁶. -4 Pa, tray rotation speed of 14 r / min, raw materials are high-purity Ti particles and high-purity Au particles in sequence, i.e., several particles with 5N purity, the bottom electrode mask is covered on the strong N-type β-Ga2O3 epitaxial layer.

[0058] 6.2) Using a vacuum thermal evaporation device, a Ti / Au metal strip bottom electrode with a size of 30μm×230μm and a thickness of 70nm is deposited at the blank position reserved in the mask plate from the top one-fifth to the edge position of the strong N-type β-Ga2O3 epitaxial layer.

[0059] Step 7: Prepare the top electrode on the weakly N-type β-Ga2O3 epitaxial layer.

[0060] 7.1) Set the evaporation current to 125A, the evaporation rate to 1nm / s, and the chamber vacuum to 4×10⁻⁶. -4 Pa, tray rotation speed of 14 r / min, raw materials are high-purity Ti and Au particles, i.e., several particles with 5N purity, and a top electrode mask is covered on a weak N-type β-Ga2O3 epitaxial layer.

[0061] 7.2) Using a vacuum thermal evaporation device, a Ti / Au finger-shaped top electrode with a length of 170 μm, a width of 65 μm, a spacing between fingers of 65 μm, and a thickness of 70 nm is deposited on the top of the weak N-type β-Ga2O3 epitaxial layer at the reserved position on the mask to complete the device fabrication.

[0062] Example 2: An embedded plasma-based ultraviolet photodetector was fabricated with a substrate thickness of 0.8 mm, a buffer layer thickness of 60 nm, a photosensitive layer consisting of a strong N-type β-Ga2O3 epitaxial layer thickness of 200 nm, an intermediate Al film thickness of 5 nm, a weak N-type β-Ga2O3 epitaxial layer thickness of 200 nm, a top Al film thickness of 20 nm, a bottom electrode thickness of 50 nm and a size of 20 μm × 200 μm, a top electrode thickness of 50 nm, an interdigitated finger length of 150 μm, a finger width of 50 μm, an interdigitated finger spacing of 50 μm, and an electrode material of Ni.

[0063] Step 1: Clean the substrate and prepare a buffer layer.

[0064] A single-sided polished sapphire substrate with a thickness of 0.8 mm and a size of 1 cm × 1 cm was selected. It was ultrasonically cleaned for 15 minutes each in acetone, anhydrous ethanol, and deionized water to remove surface impurities. After cleaning, it was dried with a nitrogen gun for later use.

[0065] A gallium oxide thin film with the same shape and size as the substrate and a thickness of 60 nm was fabricated on a substrate using RF magnetron sputtering. The film was then annealed to crystallize it into a strong N-type wide-bandgap semiconductor β-Ga₂O₃ buffer layer. The process conditions for this RF magnetron sputtering method are as follows:

[0066] The substrate temperature is room temperature and the chamber vacuum level is 5 × 10⁻⁶. -4 The sputtering atmosphere was argon, the argon flow rate was 50 sccm, the sputtering power was 140 W, the working pressure was 1.2 Pa, the target material was gallium oxide, the substrate tray rotation speed was 10 r / min, and the growth time was approximately 13 min.

[0067] The annealing process conditions are as follows:

[0068] The annealing temperature is 800℃, the annealing time is 60 minutes, and the furnace tube is under vacuum.

[0069] Step 2: Prepare a strong N-type β-Ga2O3 epitaxial layer on the buffer layer.

[0070] A gallium oxide thin film with a shape and size consistent with the substrate and a thickness of 200 nm was prepared on the buffer layer by RF magnetron sputtering. The film was then annealed to crystallize the film into a strong N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer.

[0071] The process conditions for the RF magnetron sputtering method are as follows:

[0072] The substrate temperature is room temperature and the chamber vacuum level is 5 × 10⁻⁶. -4 The sputtering atmosphere was argon, the argon flow rate was 50 sccm, the sputtering power was 140 W, the working pressure was 1.2 Pa, the target material was gallium oxide, the substrate tray rotation speed was 10 r / min, and the growth time was approximately 35 min.

[0073] The annealing process conditions are as follows:

[0074] The annealing temperature is 800℃, the annealing time is 60 minutes, and the furnace tube is under vacuum.

[0075] Step 3: Prepare Al plasma units on a strong N-type β-Ga2O3 epitaxial layer.

[0076] A 5nm thick Al film with the same size and shape as the substrate was deposited on the top of a strong N-type β-Ga2O3 epitaxial layer using a vacuum thermal evaporation equipment. The film was then annealed to fuse the film into nanoparticles.

[0077] The process parameters of the vacuum thermal evaporation equipment are as follows:

[0078] The evaporation current is 90A, the evaporation rate is 0.5nm / s, and the chamber vacuum degree is 3×10⁻⁶. -4 Pa, tray rotation speed is 12 r / min, raw material is high-purity Al metal particles with a purity of 5N and a particle size of approximately 1 mm.

[0079] The annealing process conditions are as follows:

[0080] The annealing temperature was 500℃, the annealing time was 60 minutes, and the furnace tube was filled with an argon atmosphere.

[0081] Step 4: Prepare a weakly N-type β-Ga2O3 epitaxial layer on Al plasma basis.

[0082] The radio frequency magnetron sputtering method is used to first cover a weak N-type β-Ga2O3 epitaxial layer mask on an Al plasma matrix; then, a gallium oxide thin film with a thickness of 200 nm is sputtered at the reserved position of the mask; and then the film is annealed to crystallize the thin film into a weak N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer.

[0083] The process conditions for the RF magnetron sputtering method are as follows:

[0084] The substrate temperature is room temperature and the chamber vacuum level is 5 × 10⁻⁶. -4 The sputtering atmosphere was argon and oxygen, the argon flow rate was 47 sccm, the oxygen flow rate was 3 sccm, the sputtering power was 140 W, the working pressure was 1.2 Pa, the target material was gallium oxide, the substrate tray rotation speed was 10 r / min, and the growth time was approximately 35 min.

[0085] The annealing process conditions are as follows:

[0086] The annealing temperature is 800℃, the annealing time is 60 minutes, and the furnace tube is filled with air.

[0087] Step 5: Prepare Al plasma units on a weakly N-type β-Ga2O3 epitaxial layer.

[0088] An Al thin film with a thickness of 20 nm and the same size and shape as the weak N-type β-Ga2O3 epitaxial layer was deposited on top of the weak N-type β-Ga2O3 epitaxial layer using a vacuum thermal evaporation equipment. The film was then annealed to fuse the film into nanoparticles.

[0089] The process parameters of the vacuum thermal evaporation equipment are as follows:

[0090] The evaporation current is 90A, the evaporation rate is 0.5nm / s, and the chamber vacuum degree is 3×10⁻⁶. -4 Pa, tray rotation speed is 12 r / min, raw material is high-purity Al metal particles with a purity of 5N and a particle size of approximately 1 mm.

[0091] The annealing process conditions are as follows:

[0092] The annealing temperature was 500℃, the annealing time was 60 minutes, and the furnace tube was filled with an argon atmosphere.

[0093] Step 6: Prepare the bottom electrode on the strong N-type β-Ga2O3 epitaxial layer.

[0094] After covering the bottom electrode mask on the strong N-type β-Ga2O3 epitaxial layer, a Ti / Au metal strip bottom electrode with a size of 20μm×200μm and a thickness of 50nm is deposited in the blank position reserved in the mask using a vacuum thermal evaporation device at the top one-fifth to the edge position of the strong N-type β-Ga2O3 epitaxial layer.

[0095] The process parameters of the vacuum thermal evaporation equipment are as follows:

[0096] The evaporation current is 120A, the evaporation rate is 1nm / s, and the chamber vacuum degree is 3×10⁻⁶. -4Pa, tray rotation speed is 12 r / min, raw materials are high-purity Ti and Au particles (5N purity) in sequence.

[0097] Step 7: Prepare the top electrode on the weak N-type β-Ga2O3 epitaxial layer.

[0098] After covering the weak N-type β-Ga2O3 epitaxial layer with a top electrode mask, a Ni top electrode is deposited on the top of the weak N-type β-Ga2O3 epitaxial layer using a vacuum thermal evaporation device at the reserved position on the mask. The top electrode has an interdigitated finger length of 150 μm, a finger width of 50 μm, an interdigital spacing of 50 μm, and a thickness of 50 nm, thus completing the device fabrication.

[0099] The process parameters of the vacuum thermal evaporation equipment are as follows:

[0100] The evaporation current is 120A, the evaporation rate is 1nm / s, and the chamber vacuum degree is 3×10⁻⁶. -4 Pa, tray rotation speed is 12 r / min, raw materials are high-purity Ti particles and high-purity Au particles (5N purity) in sequence.

[0101] Example 3: Fabrication of an embedded plasma-based ultraviolet photodetector with a substrate thickness of 1 mm, a buffer layer thickness of 90 nm, a strong N-type β-Ga2O3 epitaxial layer thickness of 300 nm, an intermediate Al film thickness of 10 nm, a weak N-type β-Ga2O3 epitaxial layer thickness of 300 nm, a top Al film thickness of 30 nm, a bottom electrode thickness of 100 nm and a size of 40 μm × 250 μm, a top electrode thickness of 100 nm, an interdigitated finger length of 200 μm, a finger width of 80 μm, an interdigitated finger spacing of 80 μm, and an electrode material of Ti / Au.

[0102] Step A: Clean the substrate and prepare a buffer layer.

[0103] A1) A single-sided polished sapphire substrate is selected, with a thickness of 1mm and a size of 1cm×1cm;

[0104] A2) Clean it with acetone, anhydrous ethanol and deionized water for 15 minutes each to remove surface impurities. After cleaning, dry it with a nitrogen gun for later use.

[0105] A3) RF magnetron sputtering was used, with a substrate temperature of room temperature and a chamber vacuum of 9 × 10⁻⁶. -4 Under the following process conditions: Pa, sputtering atmosphere is argon, argon flow rate is 50 sccm, sputtering power is 140 W, working pressure is 1.2 Pa, target material is gallium oxide target, substrate tray rotation speed is 10 r / min, and growth time is about 19 min, a gallium oxide thin film with the same shape and size as the substrate and a thickness of 90 nm is fabricated on the substrate.

[0106] A4) The gallium oxide film was annealed at 800℃ under vacuum conditions for 60 minutes to crystallize it into a strong N-type wide bandgap semiconductor β-Ga2O3 buffer layer.

[0107] Step B: Prepare a strong N-type β-Ga2O3 epitaxial layer on the buffer layer.

[0108] B1) RF magnetron sputtering was employed, with a substrate temperature of room temperature and a chamber vacuum of 9 × 10⁻⁶. -4 Under the following process conditions: Pa, sputtering atmosphere is argon, argon flow rate is 50 sccm, sputtering power is 140 W, working pressure is 1.2 Pa, target material is gallium oxide target, substrate tray rotation speed is 15 r / min, and growth time is about 50 min, a gallium oxide thin film with the same shape and size as the substrate and a thickness of 300 nm is prepared on the buffer layer.

[0109] B2) The gallium oxide thin film was annealed at 800℃ under vacuum conditions for 60 minutes to crystallize it into a strong N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer.

[0110] Step C: Prepare Al plasmonic units on a strong N-type β-Ga2O3 epitaxial layer.

[0111] C1) Vacuum thermal evaporation equipment is used, with an evaporation current of 100A, an evaporation rate of 0.7nm / s, and a chamber vacuum degree of 5×10⁻⁶. -4 Under the process conditions of Pa, tray rotation speed of 15 r / min, and raw material of high-purity Al metal particles with a purity of 5N and a particle size of approximately 1 mm, an Al thin film with a thickness of 10 nm and a size and shape consistent with the substrate was deposited on the top of a strong N-type β-Ga2O3 epitaxial layer.

[0112] C2) The Al film was annealed at 500℃ in an argon atmosphere in the furnace tube for 60 minutes to fuse the film into nanoparticles.

[0113] Step D: Prepare a weakly N-type β-Ga2O3 epitaxial layer on an Al plasma matrix.

[0114] D1) Cover the Al plasma matrix with a weak N-type β-Ga2O3 epitaxial mask;

[0115] D2) RF magnetron sputtering was employed, with a substrate temperature of room temperature and a chamber vacuum of 9 × 10⁻⁶. -4Under the following process conditions: Pa, sputtering atmosphere of argon and oxygen, argon flow rate of 47 sccm, oxygen flow rate of 3 sccm, sputtering power of 140 W, working pressure of 1.2 Pa, target material of gallium oxide target, substrate tray rotation speed of 15 r / min, and growth time of about 50 min, a gallium oxide thin film with a thickness of 300 nm is sputtered at the reserved gap in the mask.

[0116] D3) The gallium oxide film was annealed at 800℃ in an air atmosphere in the furnace tube for 60 minutes to crystallize it into a weak N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer.

[0117] Step E: Prepare Al plasma units on a weakly N-type β-Ga2O3 epitaxial layer.

[0118] E1) Vacuum thermal evaporation equipment is used, with a plating current of 100A, a plating rate of 0.7nm / s, and a chamber vacuum degree of 5×10⁻⁶. -4 Under the process conditions of Pa, tray rotation speed of 15 r / min, and raw material of high-purity Al metal particles with a purity of 5N and a particle size of approximately 1 mm, an Al thin film with a thickness of 30 nm and the same size and shape as the weak N-type β-Ga2O3 epitaxial layer is deposited on top of the weak N-type β-Ga2O3 epitaxial layer.

[0119] E2) The Al film was annealed at 500℃ in an argon atmosphere in the furnace tube for 60 minutes to fuse the film into nanoparticles.

[0120] Step F: Prepare the bottom electrode on a strong N-type β-Ga2O3 epitaxial layer.

[0121] F1) Cover the bottom electrode mask on a strong N-type β-Ga2O3 epitaxial layer;

[0122] F2) Vacuum thermal evaporation equipment is used, with an evaporation current of 130A, an evaporation rate of 2nm / s, and a chamber vacuum of 5×10⁻⁶. -4 Under the following conditions: Pa, tray rotation speed of 15 r / min, and raw materials consisting of high-purity Ti and Au particles (i.e., several particles with 5N purity), a Ti / Au metal strip bottom electrode with a size of 50 μm × 250 μm and a thickness of 100 nm is deposited at the top one-fifth to the edge of a strong N-type β-Ga2O3 epitaxial layer.

[0123] Step G: Prepare the top electrode on a weakly N-type β-Ga2O3 epitaxial layer.

[0124] G1) Cover the top electrode mask on a weak N-type β-Ga2O3 epitaxial layer;

[0125] G2) employs a vacuum thermal evaporation equipment, with an evaporation current of 130A, an evaporation rate of 2nm / s, and a chamber vacuum of 5×10⁻⁶. -4 Under the following conditions: Pa, tray rotation speed of 15 r / min, and raw materials consisting sequentially of high-purity Ti particles and high-purity Au particles (i.e., several particles with a purity of 5N), a Ti / Au top electrode was deposited on top of a weakly N-type β-Ga2O3 epitaxial layer. This electrode has interdigitated fingers with a length of 200 μm, a width of 80 μm, an interdigital spacing of 80 μm, and a thickness of 100 nm. Device fabrication was completed.

[0126] The above descriptions are merely two specific examples of the present invention and do not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and detail without departing from the principles and structure of the present invention. For example, in addition to Ti / Au, commonly used ohmic contact metal materials such as Cr / Au can be used as electrode materials; in addition to the strip electrodes and interdigitated electrodes used in the present invention, commonly used electrodes such as circular electrodes and ring electrodes can be used as electrode shapes; the sputtering time in the RF sputtering method can be changed according to requirements, in addition to the 14-50 min used in the present invention. However, these modifications and changes based on the concept of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. An embedded plasma-based ultraviolet photodetector, comprising: The substrate (1), buffer layer (2), photosensitive layer (3), bottom electrode (4), and top electrode (5) are characterized in that: The photosensitive layer (3) adopts a multilayer semiconductor material composite structure consisting of a strong N-type wide bandgap semiconductor β-Ga2O3 layer (31), an Al plasma matrix layer (32), a weak N-type wide bandgap semiconductor β-Ga2O3 layer (33), and an Al plasma matrix layer (34) from top to bottom, so that the device has light response in the ultraviolet band and a plasma matrix layer, thereby improving the responsivity, detectivity, and response speed of the photodetector; The bottom electrode (4) is located on one side of the strong N-type wide bandgap semiconductor β-Ga2O3 layer (31) and is covered on the Al plasma matrix layer (32) to extract photogenerated carriers in the photosensitive layer, improve the carrier transport efficiency, and further improve the response speed.

2. The detector according to claim 1, characterized in that: The substrate (1) is a single-sided polished sapphire substrate with a thickness of 0.8~1mm and a size of 1cm×1cm; The buffer layer (2) is a strong N-type β-Ga2O3 thin film, which is located on the substrate and has a thickness of 60nm~90nm. Its size and shape are consistent with the substrate (1).

3. The detector according to claim 1, characterized in that: The strong N-type wide bandgap semiconductor β-Ga2O3 epitaxial layer (31) is located above the buffer layer (2), with a thickness of 200nm~300nm, and its size and shape are consistent with the substrate (1), with an electron concentration of 1×10⁻⁶. 15 cm -3 ; The Al plasma matrix layer (32) has a thickness of 5nm~10nm and its size and shape are consistent with the substrate (1); The weak N-type wide bandgap semiconductor β-Ga2O3 layer (33) has a thickness of 200nm~300nm, a size of 0.7cm×1cm, and an electron concentration of 1×10⁻⁶. 13 cm -3 ; The Al plasma matrix layer (34) has a thickness of 20 nm to 30 nm and its size and shape are consistent with the weak N-type wide bandgap semiconductor β-Ga2O3 layer (33).

4. The detector according to claim 1, characterized in that: The bottom electrode (4) has a thickness of 50nm~100nm, is strip-shaped, and has a size of 20~40μm×200~250μm. It is located on the edge of the top Al plasma matrix layer (32) away from the top electrode (5), and forms an ohmic contact with the strong N-type β-Ga2O3 film (31) and is in contact with the Al plasma matrix. The top electrode (5) has a thickness of 50nm~100nm, is finger-shaped, has a finger length of 150~200μm, a finger width of 50~80μm, and a finger spacing of 50~80μm; it is located on top of the weak N-type β-Ga2O3 epitaxial layer (33) and the Al plasma matrix layer (34), and forms an ohmic contact with the weak N-type β-Ga2O3 epitaxial layer (33) and is in contact with the Al plasma matrix; Both the bottom electrode (4) and the top electrode (5) are made of either Ti / Au or Cr / Au metallic materials.

5. A method for fabricating an embedded plasma-based ultraviolet photodetector, characterized in that, include: S1) Select a single-sided polished sapphire substrate, clean it, and then dry it with nitrogen. S2) A gallium oxide film with a thickness of 60nm~90nm was epitaxially grown on the polished surface of a sapphire substrate by RF magnetron sputtering and then annealed in a vacuum to crystallize it into a β-Ga2O3 buffer layer (2); S3) A photosensitive layer (3) is fabricated on the β-Ga2O3 buffer layer (2) by RF magnetron sputtering and vacuum thermal evaporation equipment; S4) Using a vacuum thermal evaporation equipment and a bottom electrode mask, a 50nm~100nm Ti / Au bottom electrode (4) is prepared at the top edge of the plasma matrix layer (32); S5) Using a vacuum thermal evaporation equipment and a top electrode mask, a 50nm~100nm thick Ti / Au top electrode (5) is prepared on the top of the plasma matrix layer (34) away from the bottom electrode to complete the fabrication of the photodetector.

6. The method according to claim 5, characterized in that: In step S3), a photosensitive layer (3) is fabricated on the β-Ga2O3 buffer layer (2) using RF magnetron sputtering and vacuum thermal evaporation equipment. The process includes: S3a) Gallium oxide with a thickness of 200 nm to 300 nm was further epitaxially grown on the buffer layer by RF magnetron sputtering and then annealed in vacuum to crystallize it into a strong N-type β-Ga2O3 layer (31); S3b) An Al film with a thickness of 5nm~10nm was deposited on the annealed β-Ga2O3 layer using a vacuum thermal evaporation equipment, and then annealed in a vacuum to fuse it into Al nanoparticles to form a plasma matrix layer (32). S3c) Gallium oxide with a thickness of 200 nm to 300 nm was prepared on Al plasma matrix layer (32) by RF magnetron sputtering and weak N-type β-Ga2O3 epitaxial layer mask, and then annealed in air to crystallize into weak N-type β-Ga2O3 epitaxial layer (33). S3d) An Al film with a thickness of 20nm~30nm is deposited on the annealed β-Ga2O3 layer using a vacuum thermal evaporation equipment and a weak N-type β-Ga2O3 epitaxial layer mask, and then annealed in a vacuum to fuse it into Al nanoparticles, forming a plasma matrix layer (34), thus completing the preparation of the photosensitive layer (3).

7. The method according to claim 5, characterized in that, The β-Ga2O3 thin film is grown using RF magnetron sputtering, and the process conditions are as follows: The sputtering power is 140W. The substrate temperature is room temperature. The target material is β-Ga2O3. The working pressure is 1.2 Pa. Argon flow rate is 50 sccm. Oxygen flow rate is 0 sccm Or the argon flow rate is 47 sccm Oxygen flow rate is 3 sccm Sputtering time is 15 min to 68 min. The chamber vacuum level is 5×10 -4 Pa~9×10 -4 Pa, The substrate tray rotates at a speed of 10 r / min to 15 r / min.

8. The method according to claim 6, characterized in that, The vacuum evaporation process used to prepare the Al film employs the following conditions: The vapor deposition current is 90A~100A. The evaporation rate is 0.5 nm / s to 0.7 nm / s. Vacuum degree is 3×10 -4 Pa~5×10 -4 Pa, The tray rotates at a speed of 12 r / min to 15 r / min. The raw material is one Al particle with a purity of 5N.

9. The method according to claim 6, characterized in that, The annealing process for the β-Ga2O3 thin film is as follows: The annealing temperature is 800℃. The annealing time is 60 minutes. The annealing process for the Al thin film is as follows: The annealing temperature is 500℃. The annealing time is 60 minutes.

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