A PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region and preparation method thereof

Abstract

The present invention discloses a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region and a preparation method thereof, and relates to the field of solar-blind ultraviolet photodetectors. The present invention first deposits a layer of intrinsic gallium oxide as an i-layer on a p-type gallium nitride substrate, and then deposits a layer of silicon-doped n-type gallium oxide layer to form a PIN heterojunction. By reasonably regulating the doping concentration and the thickness of the i-type gallium oxide layer, the i-type gallium oxide layer as the main light-absorbing layer is fully depleted. Subsequently, ohmic contacts of p-type gallium nitride and n-type gallium oxide are prepared on the PIN heterojunction, respectively, to obtain a PIN heterojunction photodetector based on gallium oxide. Compared with conventional gallium oxide-based pn heterojunction photodetectors, the PIN heterojunction photodetector prepared in the present invention has excellent device performance, including shorter response time, greater responsivity, greater light-to-dark current ratio, good transient response characteristics and stability.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor photoelectric detectors, and in particular to an active region fully depleted PIN heterojunction solar-blind ultraviolet high-speed photoelectric detector and a preparation method thereof. Background Art

[0002] The first generation of semiconductors represented by silicon and germanium play a very important role in the field of microelectronics. However, with the development of technology, due to the narrow bandgap and low breakdown electric field of silicon, it is difficult to meet the requirements of high-frequency, high-power devices and optoelectronics. After silicon and germanium, the second generation of semiconductors appeared, such as gallium arsenide and silicon germanium, which have higher electron mobility, larger bandgap, better optoelectronic properties, and are more suitable for high-speed, high-frequency, high-temperature and high-power electronic devices. In recent years, the third generation of semiconductor materials with a bandgap greater than 2.3eV, such as silicon carbide, gallium nitride, aluminum nitride, zinc oxide, and gallium oxide, have emerged. Compared with the first two generations of semiconductor materials, this type of material has a large bandgap, high breakdown electric field strength, fast saturated electron drift velocity, large thermal conductivity, small dielectric constant, strong radiation resistance, and good chemical stability. It is very suitable for the development of radiation-resistant, high-frequency, high-power and high-density integrated semiconductor devices.

[0003] Gallium oxide (Ga2O3) is an emerging wide bandgap semiconductor (bandgap width is 4.9eV), with a wider bandgap width and higher breakdown field strength than gallium nitride and silicon carbide (3.3eV), and is the preferred material for the new generation of ultra-high power devices. As a rising star in the semiconductor field, gallium oxide materials and devices have received strong attention from academia and industry in various countries. On the other hand, when sunlight passes through the atmosphere, due to the strong absorption of the ozone layer, ultraviolet light in the 200nm-280nm band is almost non-existent near the ground, so the light in this band is also called solar-blind ultraviolet light, and the detector based on this band is a solar-blind ultraviolet photodetector. Because the interference of sunlight background radiation is avoided, the solar-blind ultraviolet photodetector has outstanding advantages such as low background noise, low false alarm rate, and strong anti-interference. It is widely used in missile warning, high-voltage power grid corona detection, flame detection, deep ultraviolet disinfection and sterilization, etc. The bandgap width of gallium oxide corresponds to a wavelength of 260nm, which just falls in the solar-blind ultraviolet region. Gallium oxide-based photodetectors only respond to solar-blind ultraviolet light and are ideal semiconductor materials for solar-blind detectors. A core indicator of photodetectors is response speed. In order to detect rapidly changing signals, we hope that the response speed is as fast as possible. In pn junction photodetectors, the existence of a built-in electric field can promote the separation of photogenerated carriers and improve the response speed of the detector. Therefore, pn junctions are often used for the preparation of high-speed photodetectors. Since the preparation of p-type gallium oxide is still relatively difficult, other p-type materials are often used to form a pn heterojunction with n-type gallium oxide. The area that mainly absorbs light in a pn junction photodetector is called the active region, and the active region that contributes to the photocurrent mainly comes from the depletion region, so the depletion region is very critical. However, most reported pn heterojunction photodetectors often have a narrow width of the depletion region due to heavy doping in the p-region or n-region, thereby limiting the performance of the photodetector. Summary of the invention

[0004] The present invention provides a method for preparing a high-speed photodetector. By rationally regulating the device structure and the depletion region, the photodetector has a fully depleted active region, and the performance of the photodetector is significantly improved. The problem of device performance being limited due to the narrow depletion region width in traditional pn junction photodetectors is improved.

[0005] The present invention provides a method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active regions, comprising the following steps:

[0006] 1) placing the alumina substrate (1) in acetone, ethanol and deionized water for ultrasonic cleaning in sequence for 10 to 15 minutes, and then drying it with a nitrogen gun;

[0007] 2) growing a gallium nitride buffer layer (2) on an aluminum oxide substrate (1) using a MOCVD (metal organic chemical vapor deposition) technique;

[0008] 3) growing a non-doped gallium nitride layer (3) on the gallium nitride buffer layer (2) using MOCVD technology;

[0009] 4) growing a p-type gallium nitride layer (4) on the non-doped gallium nitride layer (3) using MOCVD technology. The p-type gallium nitride layer (4) is a p-type layer;

[0010] 5) Place the sample in acetone, ethanol, and deionized water and ultrasonically clean it for 10 to 15 minutes, then blow dry it with a nitrogen gun;

[0011] 6) growing a non-doped intrinsic gallium oxide layer on one side of the p-type gallium nitride layer (4) using PLD (pulsed laser deposition) technology. The intrinsic gallium oxide layer is an i-type gallium oxide layer (6);

[0012] 7) growing an n-type gallium oxide layer (7) on the i-type gallium oxide layer (6) using PLD technology. The n-type gallium oxide layer (7) is an n-type layer;

[0013] 8) pre-treating the deposition area of ​​the p-type ohmic contact electrode (5) using argon plasma;

[0014] 9) coating a p-type ohmic contact electrode (5) on the other side of the p-type gallium nitride layer (4) by using a magnetron sputtering technique;

[0015] 10) placing the sample in a rapid annealing furnace to anneal the p-type ohmic contact electrode (5) to improve the p-type ohmic contact;

[0016] 11) coating an n-type ohmic contact electrode (8) on the n-type gallium oxide layer (7) by using a magnetron sputtering technique;

[0017] 12) The sample is placed in a rapid annealing furnace to anneal the n-type ohmic contact electrode (8) to improve the n-type ohmic contact.

[0018] Preferably, the size of the alumina substrate (1) is 5 mm×10 mm×0.5 mm, and the alumina orientation is c-plane.

[0019] Preferably, the gallium nitride buffer layer (2) has a thickness of 50 nm to 70 nm.

[0020] Preferably, the thickness of the undoped gallium nitride layer (3) is 2 μm to 2.5 μm.

[0021] Preferably, the p-type gallium nitride layer (4) has a thickness of 2 μm to 2.5 μm and a carrier concentration of 5×10 17 cm3 ~5×10 18 cm 3 .

[0022] Preferably, the thickness of the i-type gallium oxide layer (6) is 200 nm to 250 nm, and the carrier concentration is 1×10 16 cm 3 ~2.1×10 16 cm 3 .

[0023] Preferably, the growth process conditions of the i-type gallium oxide layer (6) are as follows: PLD uses a non-doped gallium oxide target, and the frequency and energy density of the pulsed laser are 4-6 Hz and 1.3-1.5 J / cm 2 , the distance between the target and the substrate is 4.5 to 5.5 cm, the growth temperature is 630 to 670° C., and the oxygen pressure is 1 Pa to 1.5 Pa. In order to reduce the carrier concentration of the i-type gallium oxide layer (6), after the i-type gallium oxide layer (6) is deposited, the growth chamber temperature is reduced to 590 to 610° C., the oxygen pressure is increased to 30 kPa to 101 kPa, and the sample is annealed in a high oxygen pressure environment for 10 min to 30 min.

[0024] Preferably, the thickness of the n-type gallium oxide layer (7) is 30 nm to 50 nm, and the carrier concentration is 5×10 18 cm 3 ~5×10 19 cm 3 .

[0025] Preferably, the growth process conditions of the n-type gallium oxide layer (7) are as follows: PLD uses a 0.5% silicon-doped gallium oxide target, and the frequency and energy density of the pulsed laser are 4-6 Hz and 1.3-1.5 J / cm 2 The distance between the target and the substrate is 4.5-5.5 cm, the growth temperature is 590-610°C, and the oxygen pressure is 1Pa-1.5Pa.

[0026] Preferably, the process conditions of the argon plasma pretreatment are: a metal mask is used to cover the surface of the sample, exposing only the area where the p-type ohmic contact electrode (5) is subsequently deposited. The sample is placed with the metal mask side facing upward into a plasma degumming machine for pretreatment in an argon environment, with a power of 100W to 150W, an argon flow rate of 150sccm to 200sccm, and a treatment time of 5min to 10min.

[0027] Preferably, the growth process conditions of the p-type ohmic contact electrode (5) are as follows: magnetron sputtering Ni / Au is used as the p-type ohmic contact electrode (5). When sputtering Ni and Au, the sputtering power is 150W to 200W, the argon gas flow rate is 30sccm to 50sccm, and the gas pressure is 0.5Pa to 1Pa. First, 20nm to 50nm of Ni is sputtered, and then 20nm to 50nm of Au is sputtered.

[0028] Preferably, the annealing conditions of the p-type ohmic contact electrode (5) are: annealing in a rapid annealing furnace, the annealing temperature is 500° C., the annealing atmosphere is air, and the annealing time is 3 min to 5 min.

[0029] Preferably, the growth process conditions of the n-type ohmic contact electrode (8) are as follows: magnetron sputtering Ti / Au is used as the n-type ohmic contact electrode (8). When sputtering Ti, the sputtering power is 100W to 150W, the argon flow rate is 30sccm to 50sccm, and the gas pressure is 0.5Pa to 1Pa. When sputtering Au, the sputtering power is 150W to 200W, the argon flow rate is 30sccm to 50sccm, and the gas pressure is 0.5Pa to 1Pa. First, 20nm to 50nm of Ti is sputtered, and then 20nm to 50nm of Au is sputtered.

[0030] Preferably, the annealing conditions of the n-type ohmic contact electrode (8) are: annealing in a rapid annealing furnace, an annealing temperature of 550° C., an annealing atmosphere of nitrogen, and an annealing time of 2 min to 4 min.

[0031] The present invention precisely controls the thickness of each layer and the carrier concentration in the pin heterojunction so that the prepared pin heterojunction photodetector has a fully depleted active region. Under the action of the fully depleted active region, the response speed and various photoelectric properties of the photodetector, such as responsivity and detection rate, are greatly improved. Compared with the same type of photodetectors, the pin heterojunction day-blind ultraviolet high-speed photodetector with fully depleted active region prepared in the present invention has the advantages of faster response speed, greater responsivity, etc., and is suitable for scenes with strict requirements on response speed and accuracy. At the same time, the preparation method is simple, the cost is low, the repeatability is high, and the prepared photodetector is highly stable, so the present invention has practical value.

[0032] The present invention provides a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region and a preparation method thereof, which has the following advantages:

[0033] 1) Since the photodetector has a fully depleted active region, the photogenerated carriers can be directly separated and drifted at high speed under the action of the built-in electric field, reducing the diffusion distance of the carriers, thereby greatly improving the response speed of the photodetector.

[0034] 2) Since the depletion region of the photodetector is effectively widened, the light absorption efficiency of the photodetector is improved, thereby significantly improving the photoelectric performance of the photodetector, such as photocurrent, response, and detection rate.

[0035] 3) The present invention does not involve complicated preparation processes, the preparation method is simple, and the repeatability is high, and the prepared photodetector has excellent photoelectric performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the structure of the prepared photodetector, in which PD2-pn is used as the experimental control group;

[0037] Figure 2 is a cross-sectional scanning electron microscope image of the prepared photodetector;

[0038] Figure 3 is the response speed of the prepared photodetector;

[0039] Figure 4 is the responsivity curve of the prepared photodetector;

[0040] Figure 5 This is a stability test diagram of the prepared photodetector.

[0041] Figure 6 It is a schematic diagram of the structure of the present invention. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

[0043] Example 1

[0044] Figure 1 Two types of photodetectors are presented, Figure 1 (a) is a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region proposed by the present invention, Figure 1 (b) A conventional pn heterojunction photodetector is used as the experimental control group.

[0045] See also Figure 6 The invention relates to a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region, which comprises, from bottom to top: an aluminum oxide substrate (1), a gallium nitride buffer layer (2), an undoped gallium nitride layer (3), a p-type gallium nitride layer (4), a p-type ohmic contact electrode (5) and an i-type gallium oxide layer (6) located on the upper surface of the p-type gallium nitride layer (4), an n-type gallium oxide layer (7) located on the upper surface of the i-type gallium oxide layer (6), and an n-type ohmic contact electrode (8) located on the upper surface of the n-type gallium oxide layer (7).

[0046] A method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region, the steps are as follows:

[0047] 1) A c-plane alumina substrate (1) with a size of 5 mm×10 mm×0.5 mm was ultrasonically cleaned in acetone, ethanol, and deionized water for 10 min in sequence, and then dried with a nitrogen gun;

[0048] 2) growing a 50 nm thick gallium nitride buffer layer (2) on the aluminum oxide substrate (1) using MOCVD technology;

[0049] 3) growing a 2 μm non-doped gallium nitride layer (3) on the gallium nitride buffer layer (2) using MOCVD technology;

[0050] 4) A 2 μm thick layer with a carrier concentration of 5×10 17 cm 3 A p-type gallium nitride layer (4);

[0051] 5) Place the sample in acetone, ethanol, and deionized water and ultrasonically clean it for 10 min in sequence, then blow dry it with a nitrogen gun;

[0052] 6) Using PLD technology, grow a 200 nm thick layer on one side of the p-type gallium nitride layer (4) with a carrier concentration of 2.1×10 16 cm 3 The PLD uses a non-doped gallium oxide target, and the frequency and energy density of the pulsed laser are 5 Hz and 1.4 J / cm 2 , the distance between the target and the substrate is 5 cm, the growth temperature is 650° C., and the oxygen pressure is 1 Pa. In order to reduce the carrier concentration of the i-type gallium oxide layer (6), after the i-type gallium oxide layer (6) is deposited, the growth chamber temperature is reduced to 600° C., the oxygen pressure is increased to 30 kPa, and the sample is annealed in a high oxygen pressure environment for 15 minutes;

[0053] 7) Using PLD technology, a 50 nm thick layer with a carrier concentration of 8×10 18 cm 3 The PLD uses a 0.5% silicon-doped gallium oxide target, and the frequency and energy density of the pulsed laser are 5 Hz and 1.4 J / cm 2 , the distance between the target and the substrate is 5 cm, the growth temperature is 600 ° C, and the oxygen pressure is 1 Pa;

[0054] 8) Pre-treating the deposition area of ​​the p-type ohmic contact electrode (5) using argon plasma. Covering the surface of the sample with a metal mask, only the area where the p-type ohmic contact electrode (5) is subsequently deposited is exposed. The sample with the metal mask facing upward is placed in a plasma degumming machine for pre-treatment in an argon environment, with a power of 100 W, an argon flow rate of 150 sccm, and a treatment time of 5 minutes;

[0055] 9) A p-type ohmic contact electrode (5) is plated on the other side of the p-type gallium nitride layer (4) using magnetron sputtering technology. Magnetron sputtered Ni / Au is used as the p-type ohmic contact electrode (5). When sputtering Ni and Au, the sputtering power is 150W, the argon gas flow rate is 30sccm, and the gas pressure is 0.5Pa. First, 20nm of Ni is sputtered, and then 20nm of Au is sputtered;

[0056] 10) placing the sample in a rapid annealing furnace to anneal the p-type ohmic contact electrode (5) to improve the p-type ohmic contact. The annealing temperature is 500° C., the annealing atmosphere is air, and the annealing time is 5 minutes;

[0057] 11) An n-type ohmic contact electrode (8) is plated on the n-type gallium oxide layer (7) using magnetron sputtering technology. Magnetron sputtered Ti / Au is used as the n-type ohmic contact electrode (8). When sputtering Ti, the sputtering power is 100W, the argon flow rate is 30sccm, and the gas pressure is 0.5Pa. When sputtering Au, the sputtering power is 150W, the argon flow rate is 30sccm, and the gas pressure is 0.5Pa. First, 20nm of Ti is sputtered, and then 20nm of Au is sputtered;

[0058] 12) The sample is placed in a rapid annealing furnace to anneal the n-type ohmic contact electrode (8) to improve the n-type ohmic contact. The annealing temperature is 550° C., the annealing atmosphere is nitrogen, and the annealing time is 2 minutes.

[0059] Comparative Example 1

[0060] A conventional pn heterojunction photodetector comprises: an aluminum oxide substrate (1), a gallium nitride buffer layer (2), a non-doped gallium nitride layer (3), a p-type gallium nitride layer (4), a p-type ohmic contact electrode (5) and an n-type gallium oxide layer (7) located on the upper surface of the p-type gallium nitride layer (4), and an n-type ohmic contact electrode (8) located on the upper surface of the n-type gallium oxide layer (7). Compared with Example 1, the photodetector of the comparative example differs only in that it does not contain an i-type gallium oxide layer (6).

[0061] The preparation methods of each layer are the same as those in Example 1.

[0062] Figure 2 The cross-sectional scanning electron microscope images of the two heterojunctions prepared in Example 1 and Comparative Example 1 are shown respectively.

[0063] Figure 3 The response speeds of the two photodetectors under the same test environment are shown. It can be seen that the active region fully depleted PIN heterojunction day-blind ultraviolet high-speed photodetector proposed in the present invention has a faster response speed, which is specifically reflected in shorter rise and fall times.

[0064] Figure 4 The responsivity curves of the two photodetectors under the same test environment are shown. It can be seen that the active region fully depleted PIN heterojunction solar-blind ultraviolet high-speed photodetector proposed in the present invention has a greater responsivity and better selectivity for the solar-blind region.

[0065] Figure 5 The stability test diagrams of the two photodetectors are shown, and it can be seen that the active region fully depleted PIN heterojunction day-blind ultraviolet high-speed photodetector proposed in the present invention has good stability, and the performance of the photodetector will not be significantly degraded after being placed for a long time.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region, characterized in that: The invention comprises, from bottom to top, an aluminum oxide substrate (1), a gallium nitride buffer layer (2), an undoped gallium nitride layer (3), a p-type gallium nitride layer (4), a p-type ohmic contact electrode (5) located in one area of ​​the upper surface of the p-type gallium nitride layer (4), an i-type gallium oxide layer (6) located in another area of ​​the upper surface of the p-type gallium nitride layer (4), an n-type gallium oxide layer (7) located on the upper surface of the i-type gallium oxide layer (6), and an n-type ohmic contact electrode (8) located on the upper surface of the n-type gallium oxide layer (7); a gap is left between the p-type ohmic contact electrode (5) and the i-type gallium oxide layer (6); The thickness of the gallium nitride buffer layer (2) is 50 nm to 70 nm; the thickness of the undoped gallium nitride layer (3) is 2 μm to 2.5 μm; The thickness of the p-type gallium nitride layer (4) is 2 μm to 2.5 μm, and the carrier concentration is 5×10 17 cm -3 ~5×10 18 cm -3 ; The thickness of the i-type gallium oxide layer (6) is 200 nm to 250 nm, and the carrier concentration is 1×10 16 cm -3 ~2.1×10 16 cm -3 ; The thickness of the n-type gallium oxide layer (7) is 30 nm to 50 nm, and the carrier concentration is 5×10 18 cm -3 ~5×10 19 cm -3 .

2. A method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region, characterized in that: The following steps are involved: 1) placing the alumina substrate (1) in acetone, ethanol and deionized water for ultrasonic cleaning in sequence for 10 to 15 minutes, and then drying it with a nitrogen gun; 2) growing a gallium nitride buffer layer (2) on an aluminum oxide substrate (1) using MOCVD technology; 3) growing a non-doped gallium nitride layer (3) on the gallium nitride buffer layer (2) using MOCVD technology; 4) growing a p-type gallium nitride layer (4) on the non-doped gallium nitride layer (3) using MOCVD technology; the p-type gallium nitride layer (4) is a p-type layer; 5) Place the sample in acetone, ethanol, and deionized water and ultrasonically clean it for 10 to 15 minutes, then blow dry it with a nitrogen gun; 6) growing a non-doped intrinsic gallium oxide layer on one side of the p-type gallium nitride layer (4) using a PLD technique; the intrinsic gallium oxide layer is an i-type gallium oxide layer (6); 7) growing an n-type gallium oxide layer (7) on the i-type gallium oxide layer (6) using PLD technology; the n-type gallium oxide layer (7) is an n-type layer; 8) pre-treating the deposition area of ​​the p-type ohmic contact electrode (5) using argon plasma; 9) coating a p-type ohmic contact electrode (5) on the other side of the p-type gallium nitride layer (4) by using a magnetron sputtering technique; 10) placing the sample in a rapid annealing furnace to anneal the p-type ohmic contact electrode (5) to improve the p-type ohmic contact; 11) coating an n-type ohmic contact electrode (8) on the n-type gallium oxide layer (7) by using a magnetron sputtering technique; 12) placing the sample in a rapid annealing furnace to anneal the n-type ohmic contact electrode (8) to improve the n-type ohmic contact; The size of the alumina substrate (1) is 5 mm×10 mm×0.5 mm, and the alumina is oriented in the c-plane; The thickness of the gallium nitride buffer layer (2) is 50 nm to 70 nm; the thickness of the undoped gallium nitride layer (3) is 2 μm to 2.5 μm; The thickness of the p-type gallium nitride layer (4) is 2 μm to 2.5 μm, and the carrier concentration is 5×10 17 cm -3 ~5×10 18 cm -3 ; The thickness of the i-type gallium oxide layer (6) is 200 nm to 250 nm, and the carrier concentration is 1×10 16 cm -3 ~2.1×10 16 cm -3 ; The thickness of the n-type gallium oxide layer (7) is 30 nm to 50 nm, and the carrier concentration is 5×10 18 cm -3 ~5×10 19 cm -3 .

3. The method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region according to claim 2, characterized in that: The growth process conditions of the i-type gallium oxide layer (6) are as follows: PLD uses a non-doped gallium oxide target material, and the frequency and energy density of the pulsed laser are 4-6 Hz and 1.3-1.5 J / cm 2 , the distance between the target and the substrate is 4.5 to 5.5 cm, the growth temperature is 630 to 670° C., and the oxygen pressure is 1 Pa to 1.5 Pa; in order to reduce the carrier concentration of the i-type gallium oxide layer (6), after the i-type gallium oxide layer (6) is deposited, the growth chamber temperature is reduced to 590 to 610° C., the oxygen pressure is increased to 30 kPa to 101 kPa, and the sample is annealed in a high oxygen pressure environment for 10 min to 30 min.

4. The method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region according to claim 2, characterized in that: The growth process conditions of the n-type gallium oxide layer (7) are as follows: PLD uses a 0.4-0.6% silicon-doped gallium oxide target material, and the frequency and energy density of the pulsed laser are 4-6 Hz and 1.3-1.5 J / cm 2 , the distance between the target and the substrate is 4.5-5.5 cm, the growth temperature is 590-610°C, and the oxygen pressure is 1Pa-1.5Pa.

5. The method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region according to claim 2, characterized in that: The process conditions of the argon plasma pretreatment are: using a metal mask to cover the surface of the sample, leaving only the area where the p-type ohmic contact electrode (5) is subsequently deposited exposed; placing the sample with the metal mask facing upward into a plasma degumming machine for pretreatment in an argon environment, with a power of 100W to 150W, an argon flow rate of 150sccm to 200sccm, and a treatment time of 5min to 10min.

6. The method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region according to claim 2, characterized in that: The growth process conditions of the p-type ohmic contact electrode (5) are as follows: using magnetron sputtered Ni / Au as the p-type ohmic contact electrode (5); when sputtering Ni and Au, the sputtering power is 150W-200W, the argon gas flow rate is 30sccm-50sccm, and the gas pressure is 0.5Pa-1Pa; first sputtering 20nm-50nm Ni, and then sputtering 20nm-50nm Au.

7. The method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region according to claim 2, characterized in that: The growth process conditions of the n-type ohmic contact electrode (8) are as follows: magnetron sputtered Ti / Au is used as the n-type ohmic contact electrode (8); when sputtering Ti, the sputtering power is 100W-150W, the argon gas flow rate is 30sccm-50sccm, and the gas pressure is 0.5Pa-1Pa; when sputtering Au, the sputtering power is 150W-200W, the argon gas flow rate is 30sccm-50sccm, and the gas pressure is 0.5Pa-1Pa; first sputtering 20nm-50nm of Ti, and then sputtering 20nm-50nm of Au.

8. The method for preparing a PIN heterojunction solar-blind ultraviolet high-speed photodetector with fully depleted active region according to claim 2, characterized in that: The annealing conditions of the p-type ohmic contact electrode (5) are: annealing in a rapid annealing furnace, the annealing temperature is 500° C., the annealing atmosphere is air, and the annealing time is 3 min to 5 min; the annealing conditions of the n-type ohmic contact electrode (8) are: annealing in a rapid annealing furnace, the annealing temperature is 550° C., the annealing atmosphere is nitrogen, and the annealing time is 2 min to 4 min.

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