An AlGaN / Nb2C-based ultraviolet photodetector and its preparation method

Abstract

The present invention discloses an AlGaN / Nb2C based ultraviolet photodetector and a preparation method thereof. The AlGaN / Nb2C based ultraviolet photodetector comprises a non-doped Ga polar surface AlN buffer layer and a non-doped Ga polar surface AlN buffer layer grown in sequence on a sapphire substrate. x Ga 1‑x An N-layer ultraviolet photodetector epitaxial wafer, an insulating layer, ohmic contact electrodes, and Schottky contact electrodes disposed thereon, and spaced mesas are designed using an array of bosses, wherein x = 0.5 to 0.8, the Schottky contact electrodes are made of a two-dimensional Nb2C material, and the insulating layer is an Al2O3 insulating layer. The AlGaN ultraviolet photodetector provided by the present invention improves its responsivity and detectivity in the ultraviolet solar-blind band.

Description

Technical Field

[0001] The present invention relates to the technical field of ultraviolet photoelectric detectors, and in particular to an AlGaN / Nb2C-based ultraviolet photoelectric detector and a preparation method thereof. Background Art

[0002] Ultraviolet photodetectors, as optoelectronic components that play an important role in defense warning, meteorological monitoring, and communications support, have attracted widespread attention. Traditional GaN-based ultraviolet photodetectors, due to the narrow bandgap of the material itself and low electron saturation mobility, have problems such as a narrow response band, weak visible light filtering, severe device heating, and poor stability. These problems make it difficult to meet the growing demand for device miniaturization, integration, and shorter wavelengths. Therefore, there is an urgent need to develop a new generation of ultraviolet photoelectric devices that can operate under 260nm wavelength deep ultraviolet light conditions and simultaneously meet the needs of device miniaturization and integration. This has led to the rise of research on III-nitride multi-compound ultraviolet photodetectors, represented by AlGaN. Therefore, the exploration of solar-blind AlGaN ultraviolet photodetectors and their implementation methods has groundbreaking revolutionary significance and social application value. Summary of the Invention

[0003] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides an AlGaN / Nb2C-based ultraviolet photodetector and a preparation method thereof. The ultraviolet photodetector is obtained by combining a novel Nb2C two-dimensional material with a non-doped Ga polar surface AlGaN. x Ga 1-x The N layer (functional layer) forms a high-efficiency Schottky contact. The Al2O3 insulating layer prevents the electrode and functional layer from forming an ohmic contact, improving Schottky contact efficiency and boosting responsivity and detectivity in the UV solar-blind band. The preparation method provided by the present invention has the advantages of high compatibility with existing production methods and ease of implementation.

[0004] The first object of the present invention is to provide an AlGaN / Nb2C based ultraviolet photodetector.

[0005] The second object of the present invention is to provide a method for preparing an AlGaN / Nb2C-based ultraviolet photodetector.

[0006] The first object of the present invention can be achieved by adopting the following technical solutions:

[0007] An AlGaN / Nb2C-based ultraviolet photodetector comprises an ultraviolet photodetector epitaxial wafer and an insulating layer, an ohmic contact electrode and a Schottky contact electrode arranged on the ultraviolet photodetector epitaxial wafer, wherein:

[0008] The ultraviolet photodetector epitaxial wafer comprises a non-doped Ga polar surface AlN buffer layer and a non-doped Ga polar surface AlN buffer layer grown in sequence on a sapphire substrate. x Ga 1-x N layers, where x = 0.5 to 0.8;

[0009] The insulating layer is arranged on the non-doped Ga polar surface Al x Ga 1-x The ohmic contact electrode is arranged on the insulating layer; the Schottky contact electrode is arranged on the ohmic contact electrode, and the inner side of the insulating layer, the ohmic contact electrode and the non-doped Ga polar surface Al x Ga 1-x On the N layer, the ohmic contact electrode is also arranged on the non-doped Ga polar surface Al x Ga 1-x The other side of the upper surface of the N layer;

[0010] The Schottky contact electrode is made of two-dimensional Nb2C material, and the insulating layer is an Al2O3 insulating layer.

[0011] Furthermore, the thickness of the non-Ga-doped polar AlN buffer layer is 350-500 nm.

[0012] Furthermore, the non-doped Ga polar surface Al x Ga 1-x The thickness of the N layer is 300~450nm.

[0013] Furthermore, the thickness of the insulating layer is 100-200 nm.

[0014] Furthermore, the ohmic contact electrode is made by Ti / Al / Ni / Au evaporation and has a thickness of 100-150 nm.

[0015] Furthermore, the non-doped Ga polar surface AlN buffer layer and the non-doped Ga polar surface Al x Ga 1-x The N layer has (0001) as the epitaxial direction.

[0016] The second object of the present invention can be achieved by adopting the following technical solutions:

[0017] A method for preparing an AlGaN / Nb2C-based ultraviolet photodetector, the method comprising:

[0018] The non-doped Ga polar AlN buffer layer and the non-doped Ga polar AlN buffer layer were grown on the sapphire substrate. x Ga 1-xN layer, obtain ultraviolet photodetector epitaxial wafer and process it; where x = 0.5~0.8;

[0019] Performing photolithography on the processed ultraviolet photodetector epitaxial wafer to obtain an isolation pattern; etching the ultraviolet photodetector epitaxial wafer after photolithography to etch a groove along the isolation pattern;

[0020] Through mask alignment, the non-doped Ga polar surface Al x Ga 1-x Photolithography is performed on one side of the N layer, and Al x Ga 1-x An insulating layer pattern is prepared on the N layer; the ultraviolet photodetector epitaxial wafer with the insulating layer pattern is placed in an electron beam evaporation device to evaporate an insulating layer to obtain an insulating layer, and the ultraviolet photodetector epitaxial wafer with the insulating layer is processed;

[0021] Through mask alignment, Al x Ga 1-x The other side of the N layer is photolithographically processed to obtain an ohmic contact electrode pattern; the ultraviolet photodetector epitaxial wafer with the ohmic contact electrode pattern is placed in an electron beam evaporation device to evaporate an ohmic contact electrode metal to obtain an ohmic contact electrode metal; and the ultraviolet photodetector epitaxial wafer with the ohmic contact electrode metal is processed;

[0022] Through mask alignment, on the ohmic contact electrode metal on one side of the insulating layer, as well as the inner side of the insulating layer, the ohmic contact electrode and the non-doped Ga polar surface Al x Ga 1-x On the N layer, photolithography is performed to obtain a Schottky contact electrode pattern; the Schottky contact electrode material is fully and evenly covered on the Schottky contact electrode pattern, and after heating and setting, an AlGaN / Nb2C-based ultraviolet photodetector is obtained, wherein the heating temperature is 50-70°C;

[0023] The Schottky contact electrode material is a two-dimensional Nb2C material, and the insulating layer is an Al2O3 insulating layer.

[0024] Furthermore, the Schottky contact electrode material is fully and evenly covered on the Schottky contact electrode pattern, and after heating and setting, an AlGaN / Nb2C-based ultraviolet photodetector is obtained, comprising:

[0025] The AlGaN rectifier epitaxial wafer with Schottky contact electrode pattern was placed on a glass slide, and Nb2CT xThe liquid droplets are evenly covered on the surface of the AlGaN rectifier epitaxial wafer, and after heating and shaping, a Schottky contact electrode is obtained, thereby making an AlGaN / Nb2C-based ultraviolet photodetector, wherein Nb2CT x The concentration of the droplets is 0.05~0.1g / mL.

[0026] Furthermore, the ohmic contact electrode is made by Ti / Al / Ni / Au evaporation and has a thickness of 100-150 nm.

[0027] Furthermore, the non-doped Ga polar surface AlN buffer layer and the non-doped Ga polar surface Al x Ga 1-x The N layer has (0001) as the epitaxial direction.

[0028] The present invention has the following beneficial effects compared to the prior art:

[0029] 1. The preparation method provided by the present invention adopts a novel two-dimensional Nb2C material in the design of the Schottky contact electrode structure, thereby increasing the photocurrent by improving the electron mobility.

[0030] 2. The present invention uses Group III nitrides represented by AlGaN as the basic material for ultraviolet photodetectors. Group III nitrides have more excellent material properties than traditional Si chips and can better realize the miniaturization and integration of devices in shorter wavelength applications.

[0031] 3. The present invention uses Ga polar surface III nitride as the device substrate material, and the surface morphology of the epitaxial material is better, which can greatly improve the contact quality of the metal electrode and the interface quality between the Schottky electrode and the epitaxial material.

[0032] 4. The present invention designs an Al2O3 insulating layer structure, which effectively overcomes the disadvantage that two-dimensional Nb2C is easily oxidized during the high-temperature electrode preparation process, and enables two-dimensional Nb2C to be used as a Schottky electrode to modify AlGaN-based ultraviolet photodetectors.

[0033] 5. The present invention uses a transparent sapphire substrate material as the device epitaxial substrate to facilitate the collection and transmission of optical signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the structure of an AlGaN / Nb2C-based ultraviolet photodetector according to an embodiment of the present invention.

[0036] Figure 2 This is an AFM characterization image of the Ga-polar AlGaN-based device epitaxial wafer of Example 2 of the present invention.

[0037] Figure 3 This is an IV curve test diagram of the AlGaN / Nb2C-based ultraviolet photodetector according to Example 2 of the present invention.

[0038] Figure 1 middle:

[0039] 1- sapphire substrate, 2- non-doped Ga polar surface AlN buffer layer, 3- non-doped Ga polar surface Al x Ga 1-x N layer, 4-insulating layer, 5-ohmic contact electrode, 6-Schottky contact electrode. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. It should be understood that the specific embodiments described are only used to explain this application and are not used to limit this application.

[0041] Example 1:

[0042] This embodiment provides a method for preparing an AlGaN / Nb2C-based ultraviolet photodetector, comprising the following steps:

[0043] (1) Figure 1 As shown, a non-doped Ga polar surface AlN buffer layer 2 and a non-doped Ga polar surface AlN buffer layer 3 are sequentially grown on a sapphire substrate 1. x Ga 1-x N layer (thin film) 3, to obtain the ultraviolet photodetector epitaxial wafer;

[0044] (2) placing the AlGaN ultraviolet photodetector epitaxial wafer obtained in step (1) in acetone, deionized water, and anhydrous ethanol in sequence for ultrasonic treatment, taking it out and washing it with deionized water and then drying it with hot high-purity nitrogen;

[0045] (3) Preparation of mesa isolation pattern: The AlGaN rectifier epitaxial wafer obtained in step (2) is subjected to photolithographic preparation of insulating mesa isolation pattern: photoresist is evenly applied on the AlGaN rectifier epitaxial wafer obtained in step (2) by spin coating, the AlGaN rectifier epitaxial wafer coated with photoresist is pre-baked, and then placed in a photolithography machine for exposure, and finally the exposed epitaxial wafer is immersed in a developer for photolithographic development and cleaning;

[0046] (4) Mesa isolation: Reactive ion etching is performed on the AlGaN ultraviolet photodetector epitaxial wafer after photolithography. Grooves are etched along the boss pattern in the AlGaN ultraviolet photodetector epitaxial wafer to obtain separated and insulated bosses and then cleaned;

[0047] (5) performing photolithographic preparation of the insulating layer electrode pattern on the AlGaN rectifier epitaxial wafer obtained in step (4): aligning the AlGaN epitaxial wafer using the alignment marks in the mask, and repeating the process (3);

[0048] (6) preparing an insulating layer on the AlGaN rectifier epitaxial wafer, placing the AlGaN ultraviolet photodetector epitaxial wafer with the insulating layer pattern obtained by photolithography development in step (5) in an electron beam evaporation device, evacuating the evaporation chamber, and then evaporating an Al2O3 insulating layer 4;

[0049] (7) Immersing the AlGaN ultraviolet photodetector epitaxial wafer in a degumming solution and removing it, rinsing it with deionized water and using acetone to ultrasonically remove the photoresist and evaporated metal remaining on the surface of the AlGaN ultraviolet photodetector epitaxial wafer, then washing it with deionized water after ultrasonication, and then drying it with hot high-purity nitrogen;

[0050] (8) Aligning the AlGaN rectifier epitaxial wafer using the alignment marks in the mask, repeating the process in step (3), photolithography and development at the corresponding positions, preparing the device ohmic contact electrode pattern and cleaning;

[0051] (9) preparing an ohmic contact electrode on the AlGaN rectifier epitaxial wafer: placing the AlGaN rectifier epitaxial wafer with the ohmic contact electrode pattern developed by photolithography obtained in step (8) into an electron beam evaporation device, repeating the process of step (6) to evaporate the ohmic contact electrode metal 5 on the AlGaN ultraviolet photodetector epitaxial wafer;

[0052] (10) Repeat step (7) to remove the residual photoresist and evaporated metal on the surface of the AlGaN epitaxial wafer by soaking in a degumming solution and ultrasonic cleaning;

[0053] (11) Place the AlGaN epitaxial wafer with the metal electrode evaporated into a rapid annealing device and perform rapid annealing in a flowing N2 atmosphere;

[0054] (12) The annealed device was placed in a piranha wash solution, which was prepared by mixing concentrated sulfuric acid and 30% hydrogen peroxide in a ratio of 7:3, and soaked for 5 minutes.

[0055] (13) Aligning the AlGaN rectifier epitaxial wafer using the alignment marks in the mask, repeating the process in step (3), photolithography and development at the corresponding positions, preparing the device Schottky contact electrode pattern and cleaning;

[0056] (14) Prepare Schottky contact electrodes for AlGaN rectifier epitaxial wafers: Place the AlGaN rectifier epitaxial wafer with the Schottky contact electrode pattern obtained by photolithography in step (12) on a glass slide, and drop Nb2CT x The AlGaN / Nb2C-based ultraviolet photodetector is manufactured by heating and placing the AlGaN / Nb2C-based ultraviolet photodetector on the surface of the AlGaN epitaxial wafer.

[0057] in:

[0058] The non-doped Ga polar surface AlN buffer layer and the non-doped Ga polar surface AlN buffer layer in step (1) x Ga 1-x The N films all have (0001) as the epitaxial direction;

[0059] The ultrasonic treatment time in step (2) and step (7) is 3 to 5 minutes;

[0060] The thickness of the photoresist in step (3) is 0.5 μm, the drying time is 90 s, the exposure time is 5 to 15 s, and the development time is 50 s;

[0061] The depth of the groove in step (4) is 1 to 2.5 μm;

[0062] The vacuum degree in step (6) is 1~5×10 -5 Pa;

[0063] The annealing temperature in step (11) is 400° C. to 600° C., and the annealing time is 3 to 5 minutes.

[0064] Example 2:

[0065] This embodiment provides a method for preparing an AlGaN / Nb2C-based ultraviolet photodetector, which specifically includes:

[0066] (1) Figure 1As shown, an AlGaN ultraviolet photodetector epitaxial wafer is grown on a sapphire substrate using metal organic chemical vapor deposition technology, including a Ga polar AlN buffer layer 2 grown on a sapphire substrate 1, and a non-doped Ga polar AlGaN layer 3 grown on the Ga polar AlN buffer layer 2; wherein the thickness of the AlN buffer layer is 450nm; the thickness of the non-doped Ga polar AlGaN layer is 400nm;

[0067] (2) The AlGaN ultraviolet photodetector epitaxial wafer was placed in acetone, deionized water, and anhydrous ethanol in sequence and ultrasonicated for 3 minutes each. After removal, it was rinsed with deionized water, and the rinsed AlGaN was blown dry with hot high-purity nitrogen;

[0068] (3) Preparation of mesa isolation pattern: The cleaned AlGaN ultraviolet photodetector epitaxial wafer is spin-coated with positive photoresist, model RZJ304, with a photoresist thickness of 0.5 μm, and the epitaxial wafer coated with photoresist is placed on a hot plate for pre-baking for 90 seconds. The epitaxial wafer coated with photoresist is then placed in a photolithography machine and aligned through the mask alignment mark. The development area size is 2 mm × 1 mm. The exposure is then performed for 10 seconds. The exposed epitaxial wafer is then immersed in a positive developer, model RZX3038, for 50 seconds. Finally, the developed epitaxial wafer is taken out, rinsed with deionized water, and blown dry with hot high-purity nitrogen gas. The film is then placed on a hot plate for baking for 90 seconds.

[0069] (4) Mesa isolation pattern etching: Place the AlGaN ultraviolet photodetector epitaxial wafer after photolithography in a reactive ion etcher to perform reactive ion etching on the isolation layer pattern exposed by photolithography, and etch out a groove corresponding to the pattern with a groove depth of 2 μm. After etching, rinse the epitaxial wafer surface with deionized water and blow dry with hot nitrogen;

[0070] (5) Preparation of insulating layer pattern: Align the AlGaN ultraviolet photodetector epitaxial wafer using the alignment marks on the mask, repeat the photolithography process in step (3), perform photolithography development at the corresponding position, and prepare an exposed device insulating layer pattern area on the AlGaN ultraviolet photodetector epitaxial wafer with a size of 0.3 mm × 1 mm;

[0071] (6) Preparation of insulating layer for AlGaN ultraviolet photodetector epitaxial wafer after photolithography: Place AlGaN ultraviolet photodetector epitaxial wafer with insulating layer pattern into electron beam evaporation equipment, and pump the vacuum degree of the cavity to 3×10 -5 Pa, followed by evaporation of the insulating layer material Al2O34 with a thickness of 150nm;

[0072] (7) Immerse the AlGaN ultraviolet photodetector epitaxial wafer with the prepared insulating layer in the degumming solution for 10 minutes, remove it, rinse it with deionized water, and place it in acetone for 15 minutes of ultrasonic treatment. After taking it out, rinse it with deionized water and blow it dry with hot nitrogen;

[0073] (8) Preparation of ohmic contact electrode pattern: Align the AlGaN ultraviolet photodetector epitaxial wafer through the alignment mark in the mask plate, repeat the photolithography process in step (3), photolithography and development at the corresponding position, and prepare the device ohmic contact electrode pattern area exposed on the AlGaN ultraviolet photodetector epitaxial wafer, with a size of 2×0.2mm×1mm, located on the left and right sides of the etching table respectively;

[0074] (9) Preparation of ohmic contact electrodes for the AlGaN ultraviolet photodetector epitaxial wafer after photolithography: Place the AlGaN ultraviolet photodetector epitaxial wafer with the device ohmic contact pattern into the electron beam evaporation equipment, and pump the vacuum degree of the cavity to 1×10 -5 Pa, followed by evaporation of ohmic contact electrode materials Ti / Al / Ni / Au with a thickness of 125 nm;

[0075] (10) Repeat step (7) to remove the residual photoresist and evaporated metal on the surface of the AlGaN epitaxial wafer by soaking in a degumming solution and ultrasonic cleaning;

[0076] (11) Place the AlGaN epitaxial wafer with the metal electrode evaporated into a rapid annealing device and perform rapid annealing in a flowing N2 atmosphere at a temperature of 500 °C for 4 min.

[0077] (12) The annealed device was placed in a piranha solution for 5 minutes. The piranha solution was prepared by mixing concentrated sulfuric acid and 30% hydrogen peroxide in a ratio of 7:3.

[0078] (13) Preparation of Schottky contact electrode pattern: Align the AlGaN UV photodetector epitaxial wafer using the alignment mark in the mask, repeat the photolithography process in step (3), perform photolithography and development on the corresponding position on the insulating layer pattern side, and prepare the device Schottky contact electrode pattern area exposed on the AlGaN UV photodetector epitaxial wafer with a size of 1.6 mm × 1 mm;

[0079] (14) Prepare Schottky contact electrodes for the AlGaN ultraviolet photodetector epitaxial wafer after photolithography: Paste the AlGaN ultraviolet photodetector epitaxial wafer with the Schottky contact electrode pattern on a glass slide, and use a needle to absorb a small amount of Nb2CT xThe sample (concentration of 0.1 g / mL) was dropped onto the epitaxial wafer surface. The AlGaN UV photodetector epitaxial wafer was then placed in a vacuum oven to dry and solidify the Nb2C. Finally, the AlGaN epitaxial wafer was soaked in acetone for 50 seconds to remove any residual photoresist and Nb2C on the surface, thereby fabricating an AlGaN / Nb2C-based UV photodetector.

[0080] The structure of the solar-blind AlGaN ultraviolet photodetector prepared in this embodiment is as follows: Figure 1 As shown, the surface AFM characterization test results of AlGaN epitaxial material are as follows Figure 2 As shown in Figure 2, the surface roughness root mean square is 5.2nm, the crystal quality is very good, and the performance test results of the AlGaN / Nb2C based ultraviolet photodetector device are shown in Figure 2. Figure 3 As shown, compared with traditional MSM type metal photodetection devices, the bias response characteristics are improved by 300%, and it shows a unique self-powered response characteristic.

[0081] Example 3:

[0082] This embodiment provides a method for preparing an AlGaN / Nb2C-based ultraviolet photodetector, which specifically includes:

[0083] (1) Figure 1 As shown, an AlGaN ultraviolet photodetector epitaxial wafer is grown on a sapphire substrate using metal organic chemical vapor deposition technology, including a Ga polar AlN buffer layer 2 grown on a sapphire substrate 1, and a non-doped Ga polar AlGaN layer 3 grown on the Ga polar AlN buffer layer 2; the AlN buffer layer has a thickness of 500nm; the non-doped Ga polar AlGaN layer has a thickness of 450nm;

[0084] (2) The AlGaN ultraviolet photodetector epitaxial wafer was placed in acetone, deionized water, and anhydrous ethanol in sequence and ultrasonicated for 3 minutes each. After removal, it was rinsed with deionized water, and the rinsed AlGaN was blown dry with hot high-purity nitrogen;

[0085] (3) Preparation of mesa isolation pattern: The cleaned AlGaN ultraviolet photodetector epitaxial wafer is spin-coated with positive photoresist, model RZJ304, with a photoresist thickness of 0.3 μm, and the epitaxial wafer coated with photoresist is placed on a hot plate for pre-baking for 90 seconds. The epitaxial wafer coated with photoresist is then placed in a photolithography machine and aligned through the mask alignment mark. The development area size is 2 mm × 1 mm. The exposure is then performed for 15 seconds. The exposed epitaxial wafer is then immersed in a positive developer, model RZX3038, for 50 seconds. Finally, the developed epitaxial wafer is taken out, rinsed with deionized water, and blown dry with hot high-purity nitrogen gas. The film is then placed on a hot plate for baking for 90 seconds.

[0086] (4) Mesa isolation pattern etching: Place the AlGaN ultraviolet photodetector epitaxial wafer after photolithography in a reactive ion etcher to perform reactive ion etching on the isolation layer pattern exposed by photolithography, and etch out a groove corresponding to the pattern with a groove depth of 2.5 μm. After etching, rinse the epitaxial wafer surface with deionized water and blow dry with hot nitrogen;

[0087] (5) Preparation of insulating layer pattern: Align the AlGaN ultraviolet photodetector epitaxial wafer using the alignment marks on the mask, repeat the photolithography process in step (3), perform photolithography development at the corresponding position, and prepare an exposed device insulating layer pattern area on the AlGaN ultraviolet photodetector epitaxial wafer with a size of 0.3 mm × 1 mm;

[0088] (6) Preparation of insulating layer for AlGaN ultraviolet photodetector epitaxial wafer after photolithography: Place the AlGaN ultraviolet photodetector epitaxial wafer with insulating layer pattern into electron beam evaporation equipment, and pump the vacuum degree of the cavity to 5×10 -5 Pa, then evaporate the insulating layer 4 material Al2O3 with a thickness of 200nm;

[0089] (7) Immerse the AlGaN ultraviolet photodetector epitaxial wafer with the prepared insulating layer in the degumming solution for 5 minutes, remove it, rinse it with deionized water, and place it in acetone for 10 minutes of ultrasonic treatment. After taking it out, rinse it with deionized water and blow it dry with hot nitrogen;

[0090] (8) Preparation of ohmic contact electrode pattern: Align the AlGaN ultraviolet photodetector epitaxial wafer through the alignment mark in the mask plate, repeat the photolithography process in step (3), photolithography and development at the corresponding position, and prepare the device ohmic contact electrode pattern area exposed on the AlGaN ultraviolet photodetector epitaxial wafer, with a size of 2×0.2mm×1mm, located on the left and right sides of the etching table respectively;

[0091] (9) Preparation of ohmic contact electrode 5 on the AlGaN ultraviolet photodetector epitaxial wafer after photolithography: Place the AlGaN ultraviolet photodetector epitaxial wafer with the device ohmic contact pattern into the electron beam evaporation equipment, and pump the vacuum degree of the cavity to 1×10 -5 Pa, followed by evaporation of ohmic contact electrode materials Ti / Al / Ni / Au with a thickness of 150nm;

[0092] (10) Repeat step (9) to remove the residual photoresist and evaporated metal on the surface of the AlGaN epitaxial wafer by soaking in a degumming solution and ultrasonic cleaning;

[0093] (11) Place the AlGaN epitaxial wafer with the metal electrode evaporated into a rapid annealing device and perform rapid annealing in a flowing N2 atmosphere at a temperature of 600 °C for 3 min.

[0094] (12) The annealed device was placed in a piranha solution for 5 minutes. The piranha solution was prepared by mixing concentrated sulfuric acid and 30% hydrogen peroxide in a ratio of 7:3.

[0095] (13) Preparation of Schottky contact electrode pattern: Align the AlGaN UV photodetector epitaxial wafer using the alignment mark in the mask, repeat the photolithography process in step (3), perform photolithography and development on the corresponding position on the insulating layer pattern side, and prepare the device Schottky contact electrode pattern area exposed on the AlGaN UV photodetector epitaxial wafer with a size of 1.6 mm × 1 mm;

[0096] (14) Prepare Schottky contact electrode 6 on the AlGaN ultraviolet photodetector epitaxial wafer after photolithography: Paste the AlGaN ultraviolet photodetector epitaxial wafer with Schottky contact electrode pattern on a glass slide, and use a needle to absorb a small amount of Nb2CT x The sample (concentration of 0.05g / mL) was dropped on the surface of the epitaxial wafer. The AlGaN UV photodetector epitaxial wafer was placed in a vacuum oven to dry it to fix the Nb2C. Finally, the AlGaN epitaxial wafer was immersed in acetone for 50s to remove the residual photoresist and Nb2CT on the surface of the AlGaN epitaxial wafer. x Finally, an AlGaN / Nb2C-based ultraviolet photodetector was obtained.

[0097] The test results of the AlGaN / Nb2C-based ultraviolet photodetector prepared in this embodiment are similar to those in Example 2 and will not be repeated here.

[0098] In summary, the present invention discloses a method for sequentially growing a non-doped Ga polar surface AlN buffer layer and a non-doped Ga polar surface AlN buffer layer on a sapphire substrate. x Ga 1-xThe method comprises forming an ultraviolet photodetector epitaxial wafer by forming an isolation layer pattern groove on the ultraviolet photodetector epitaxial wafer; forming an insulating layer pattern and depositing an insulating Al2O3 layer; forming an ohmic contact electrode pattern and depositing an ohmic contact electrode on the Al2O3 layer and the epitaxial wafer layer; then forming a Schottky contact electrode pattern on the ohmic contact electrode and the epitaxial wafer layer on one side of the insulating layer, and forming a two-dimensional ultrathin Nb2C Schottky contact electrode on the electrode on the insulating layer side and the epitaxial wafer, and designing spaced mesas using arrayed bosses. The present invention achieves the fabrication of a high-performance AlGaN ultraviolet photodetector and improves the responsivity and detectivity of the AlGaN ultraviolet photodetector in the ultraviolet solar-blind band. The AlGaN / Nb2C-based ultraviolet photodetector provided by the present invention forms a Schottky contact with AlGaN and a Schottky heterojunction due to the introduction of two-dimensional Nb2C. Furthermore, the high electron mobility and stability of two-dimensional Nb2C endow the AlGaN ultraviolet photodetector with improved photoelectron transmission capabilities, photogenerated electron-hole pair separation, and photoelectron collection capabilities. Furthermore, the process utilizes arrayed platform design to separate the mesas, and by implementing the array design on a wafer-level thin film, individual devices are isolated to avoid the effects of short circuits. These characteristics give AlGaN-based ultraviolet photodetectors broader application prospects and greater performance stability in the field of solar-blind photodetectors at shorter wavelengths.

[0099] The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solution and inventive concept of the present invention within the scope disclosed by the present invention, which falls within the scope of protection of the present invention.

Claims

1. A method for preparing an AlGaN / Nb2C-based ultraviolet photodetector, characterized in that: The method comprises: The non-doped Ga polar AlN buffer layer and the non-doped Ga polar AlN buffer layer were grown on the sapphire substrate. x Ga 1-x N layer, obtain ultraviolet photodetector epitaxial wafer and process it; where x = 0.5~0.8; Performing photolithography on the processed ultraviolet photodetector epitaxial wafer to obtain an isolation pattern; etching the ultraviolet photodetector epitaxial wafer after photolithography to etch a groove along the isolation pattern; Through mask alignment, the non-doped Ga polar surface Al x Ga 1-x Photolithography is performed on one side of the N layer, and Al x Ga 1-x An insulating layer pattern is prepared on the N layer; the ultraviolet photodetector epitaxial wafer with the insulating layer pattern is placed in an electron beam evaporation device to evaporate an insulating layer to obtain an insulating layer, and the ultraviolet photodetector epitaxial wafer with the insulating layer is processed; Through mask alignment, Al x Ga 1-x The other side of the N layer is photolithographically processed to obtain an ohmic contact electrode pattern; the ultraviolet photodetector epitaxial wafer with the ohmic contact electrode pattern is placed in an electron beam evaporation device to evaporate an ohmic contact electrode metal to obtain an ohmic contact electrode metal; and the ultraviolet photodetector epitaxial wafer with the ohmic contact electrode metal is processed; Through mask alignment, on the ohmic contact electrode metal on one side of the insulating layer, as well as the inner side of the insulating layer, the ohmic contact electrode and the non-doped Ga polar surface Al x Ga 1-x On the N layer, photolithography is performed to obtain a Schottky contact electrode pattern; the ultraviolet photodetector epitaxial wafer with the Schottky contact electrode pattern is placed on a glass slide, and Nb2CT x Liquid droplets are dropped on the surface of the AlGaN rectifier epitaxial wafer and evenly covered. After heating and shaping, Schottky contact electrodes are obtained, thereby making an AlGaN / Nb2C-based ultraviolet photodetector. x The concentration of the droplets is 0.05-0.1 g / mL, the heating temperature is 50-70° C., and the insulating layer is an Al 2 O 3 insulating layer.

2. The preparation method according to claim 1, characterized in that The ohmic contact electrode is made by Ti / Al / Ni / Au evaporation and has a thickness of 100-150 nm.

3. The preparation method according to any one of claims 1 to 2, characterized in that The non-doped Ga polar surface AlN buffer layer and the non-doped Ga polar surface Al x Ga 1-x The N layer has (0001) as the epitaxial direction.

4. An AlGaN / Nb2C-based ultraviolet photodetector, prepared according to the preparation method according to any one of claims 1 to 3, characterized in that: The device comprises an ultraviolet photodetector epitaxial wafer and an insulating layer, an ohmic contact electrode and a Schottky contact electrode arranged on the ultraviolet photodetector epitaxial wafer, wherein: The ultraviolet photodetector epitaxial wafer comprises a non-doped Ga polar surface AlN buffer layer and a non-doped Ga polar surface AlN buffer layer grown in sequence on a sapphire substrate. x Ga 1-x N-layer; The insulating layer is arranged on the non-doped Ga polar surface Al x Ga 1-x The ohmic contact electrode is arranged on the insulating layer; the Schottky contact electrode is arranged on the ohmic contact electrode, and the inner side of the insulating layer, the ohmic contact electrode and the non-doped Ga polar surface Al x Ga 1-x On the N layer, the ohmic contact electrode is also arranged on the non-doped Ga polar surface Al x Ga 1-x The other side of the N layer upper surface.

5. The AlGaN / Nb2C-based ultraviolet photodetector according to claim 4, characterized in that: The thickness of the non-doped Ga polar surface AlN buffer layer is 350-500 nm.

6. The AlGaN / Nb2C-based ultraviolet photodetector according to claim 4, characterized in that: The non-doped Ga polar surface Al x Ga 1-x The thickness of the N layer is 300~450nm.

7. The AlGaN / Nb2C-based ultraviolet photodetector according to claim 4, characterized in that: The thickness of the insulating layer is 100-200 nm.

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