Novel high-speed gallium oxide solar-blind ultraviolet photoelectric detector and preparation method thereof

Abstract

The invention relates to a novel high-speed gallium oxide solar-blind ultraviolet photoelectric detector and a preparation method thereof, and the detector comprises an amorphous gallium oxide thin film layer which is provided with a vertically layered crystal structure. The vertically layered crystal structure comprises a top layer, a middle layer and a bottom layer, the thickness of the top layer is 3-5nm, and the crystallinity index is 70-80%; the thickness of the middle layer is 0.1-0.3 nm, and the crystallinity index of the middle layer is 50-60%; the thickness of the bottom layer is 95-97 nm, and the crystallinity index of the bottom layer is 20-25%. The detector is a device with spatial isolation carrier generation and transmission channels, and solves the "Response Speed (RS)" difficulty. According to the detector, the rising time is smaller than or equal to 2.2 ms, the decay time is smaller than or equal to 40 microseconds, the spectral response rate is larger than or equal to 312.6 A.W <-1 >, and the detection rate is larger than or equal to 1.7 * 10 < 14 > Jones.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor photoelectric detectors, and in particular to a novel high-speed gallium oxide solar-blind ultraviolet photoelectric detector and a preparation method thereof. Background Art

[0002] Solar-blind photodetectors are an important component of spectral detectors and play a vital role in key applications such as flame warning, safety communications, rapid target imaging and environmental monitoring. As an ultra-wide bandgap material, gallium oxide has the advantages of high absorption rate in the solar-blind area, low cost and potential for large-scale production, as well as high stability and tolerance to extreme environments compared to other widely used solar-blind photodetector materials. However, in the existing technology, most gallium oxide solar-blind photodetectors have the problems of poor responsiveness and slow response speed, which limits their application in high-tech fields. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a novel high-speed gallium oxide solar-blind ultraviolet photodetector and a preparation method thereof.

[0004] A novel high-speed gallium oxide solar-blind ultraviolet photodetector and a preparation method thereof of the present invention comprises an amorphous gallium oxide thin film layer, wherein the amorphous gallium oxide thin film layer has a vertically layered crystal structure; The vertically layered crystal structure includes a top layer, a middle layer and a bottom layer, wherein the top layer has a thickness of 3 to 5 nm and a crystallinity index of 70 to 80%; the middle layer has a thickness of 0.1 to 0.3 nm and a crystallinity index of 50 to 60%; and the bottom layer has a thickness of 95 to 97 nm and a crystallinity index of 20 to 25%.

[0005] Furthermore, the top layer of the novel high-speed gallium oxide day-blind ultraviolet photodetector described in the present invention includes a β-Ga2O3 crystal structure, and the volume proportion of the β-Ga2O3 crystal structure in the top layer is 80-85%; the grains in the top layer are nearly spherical, and the grain size is 12-13 nm.

[0006] Furthermore, the transition layer of the novel high-speed gallium oxide day-blind ultraviolet photodetector of the present invention includes a β-Ga2O3 crystal structure with a volume fraction of 15% to 25%, and the remainder is an α-Ga2O3 crystal structure; the bottom layer is amorphous gallium oxide. Among them, β-Ga2O3 has a monoclinic crystal structure (space group C2 / m), which is the most stable phase in Ga2O3 on the one hand, and this stability enables it to exist stably in a variety of preparation processes. On the other hand, the band gap width of β-Ga2O3 is about 4.8-4.9 eV, which is an ultra-wide band gap semiconductor. Its optical absorption edge is located in the ultraviolet region, and it is suitable for deep ultraviolet light detectors and optoelectronic devices. α-Ga2O3 has a corundum structure (space group R-3c), which has a good lattice match with α-Al2O3. This structure gives it a unique advantage in some optoelectronic devices. Moreover, the band gap width of α-Ga2O3 is about 5.3 eV, which is the widest band gap phase in the currently known Ga2O3. Its optical absorption edge is located in the deep ultraviolet region (200-280 nm), and it can detect solar-blind ultraviolet light without a complex alloying process. The photocurrent gradually increases from the bottom to the top layer, and the bottom layer mainly provides a lower dark current for the detector.

[0007] Furthermore, the novel high-speed gallium oxide solar-blind ultraviolet photodetector of the present invention can simultaneously meet the requirements of rise time ≤ 2.2 ms, decay time ≤ 40 μs, and spectral response rate ≥ 312.6 A·W. -1 , and the detector with detection rate ≥1.7×10^14Jones.

[0008] A method for preparing a novel high-speed gallium oxide solar-blind ultraviolet photodetector based on any of the above, characterized in that it comprises the following steps: 1) Use Si / SiO2 as the substrate of the detector; 2) depositing an amorphous gallium oxide thin film on the substrate to obtain a sample to be processed; 3) performing heat treatment on the amorphous gallium oxide film prepared in step 2) to obtain an amorphous gallium oxide film layer having a vertically layered crystal structure; 4) using photolithography technology to fabricate interdigital electrodes on the amorphous gallium oxide thin film layer; 5) Using magnetron sputtering technology, a drain electrode and a source electrode are prepared on the interdigitated electrodes to obtain a detector.

[0009] Furthermore, the heat treatment process in step 3) of the preparation method of the present invention includes placing the sample to be processed on a metal substrate, performing multiple pulse heat treatments on the top of the sample to be processed, and performing cold treatment on the substrate, thereby obtaining an amorphous gallium oxide thin film layer with a vertically layered crystal structure; The specific process of the pulse heat treatment includes: the temperature of the pulse heat treatment is 900~1000℃, the duration of the pulse heat treatment is 0.5~1s, and the frequency of the pulse heat treatment is 1~2 Hz. If the temperature of the pulse heat treatment is too high, the surface of the sample to be treated will be severely damaged, while if the temperature is too low, the crystallinity of the sample to be treated cannot reach the ideal state; if the duration of the pulse heat treatment is too long, the sample to be treated will be heated for too long, and the bottom cold treatment cannot be achieved. The result is that the sample to be treated is heated as a whole, and the heating is uniform, and the structural stratification cannot be achieved. If the time is too short, the ideal effect of crystallinity cannot be achieved; the frequency of the pulse heat treatment is too fast or too slow, and the effect of the duration is the same.

[0010] Furthermore, the deposition in step 2) of the preparation method of the present invention adopts a magnetron sputtering process.

[0011] Furthermore, the number of pulse heat treatment in step 3) of the preparation method of the present invention is 6 to 15. If the number of pulse heat treatment is too small, the crystallinity is insufficient, and if the number of pulse heat treatment is too large, the sample to be treated will be damaged.

[0012] Furthermore, the thickness of the amorphous gallium oxide thin film layer prepared by the method of the present invention is 100-110 nm. When the amorphous gallium oxide thin film layer is too thin, its photocurrent may be low and the light-to-dark current ratio may also be affected. This is because insufficient film thickness may lead to reduced light absorption efficiency, thereby reducing the generation of photogenerated carriers. In addition, a too thin amorphous gallium oxide thin film layer may also lead to poor electrode contact, further affecting the current transmission efficiency.

[0013] On the contrary, an overly thick amorphous gallium oxide film layer may lead to an increase in defect density. For example, radiation-induced defects (such as dislocations and vacancy aggregation) are more easily formed in thick films, and these defects reduce carrier mobility and effective carrier concentration, thereby affecting the operating speed of the device. Increasing the thickness of the amorphous gallium oxide film layer will widen the depletion layer width, improve the light absorption efficiency, and thus increase the photocurrent. However, when the amorphous gallium oxide film layer is too thick, the depletion layer is too wide, which may cause the dark current to increase, affect the sensitivity of the device, and cause the photocurrent to decrease. In addition, an overly thick amorphous gallium oxide film layer not only leads to an increase in dark current, thereby reducing the light-to-dark current ratio and affecting the detection performance of the device. It also slows down the response speed because the carrier transmission path becomes longer, resulting in a longer recovery transient time.

[0014] Furthermore, in step 2) of the preparation method of the present invention, when preparing the amorphous gallium oxide film, an argon-oxygen mixed gas is introduced, and the gas flow rate of the argon-oxygen mixed gas is Ar:O2=28sccm:1sccm.

[0015] Furthermore, in the novel high-speed gallium oxide solar-blind ultraviolet photodetector of the present invention, the crystalline gallium oxide thin film layer is located between the substrate and the interdigital electrodes, and the interdigital electrodes are further provided with source and drain electrodes.

[0016] Beneficial effects of the present invention: The novel high-speed gallium oxide solar-blind ultraviolet photodetector of the present invention is a device with spatially isolated carrier generation and transmission channels, which solves the "response speed (RS) dilemma". It can simultaneously meet the rise time ≤ 2.2 ms, decay time ≤ 40μs, and spectral response rate ≥ 312.6 A·W -1 , and the detection rate ≥1.7×10 14 Jones' detector.

[0017] The novel high-speed gallium oxide solar-blind ultraviolet photodetector of the present invention comprises an amorphous gallium oxide thin film layer with a vertically layered crystal structure, wherein the vertically layered crystal structure comprises a top layer, an intermediate layer and a bottom layer, wherein the thickness of the top layer is 3-5 nm, and the crystallinity index is 70-80%; the thickness of the intermediate layer is 0.1-0.3 nm, and the crystallinity index is 50-60%; the thickness of the bottom layer is 95-97 nm, and the crystallinity index is 20-25%. The top layer comprises a β-Ga2O3 crystal structure, and the volume proportion of the β-Ga2O3 crystal structure in the top layer is 80-85%; the grains in the top layer are nearly spherical, and the grain size is 12-13 nm. The top layer with a crystallinity index of 70-80% can enhance light absorption and carrier generation, and improve photocurrent by improving collection efficiency. Moreover, the improvement of crystallinity improves carrier mobility, because there are fewer defects in better crystals, which promotes electron movement. This speeds up the carrier transmission speed, shortens the response time of the detector, and thus achieves a faster light response. While the underlying dark current is reduced, this design balances the photocurrent and dark current, ensuring a high signal-to-noise ratio even in low light conditions.

[0018] Thermal treatment can achieve better film crystallinity and form a β-Ga2O3 crystal structure. The response speed of the detector is improved. The increase in crystallinity leads to an increase in carrier mobility, because materials with excellent crystallinity generally have fewer defects and enhance electron mobility. This improvement accelerates carrier transport and shortens the response time of the detector, thereby achieving a faster light response speed.

[0019] Moreover, multiple pulse heat treatment technology is used to utilize short-term high energy input to rapidly bring the surface of the amorphous gallium oxide film to a higher temperature. This rapid heating and cooling feature will produce the following effects: Rapid formation of crystal nuclei: At high temperatures, atoms gain sufficient kinetic energy to overcome the diffusion barrier and rearrange into a more ordered lattice structure, thereby promoting the formation of crystal nuclei. Selective growth of crystal nuclei: Due to the extremely short pulse heat treatment time, the temperature gradient inside the sample is obvious, and the heat treatment is mainly concentrated on the surface area. The atoms on the surface are more likely to rearrange, giving priority to forming a high-quality crystal structure.

[0020] At the same time, by controlling the temperature of the pulse heat treatment to 900~1000℃, the duration of the pulse heat treatment to 0.5~1s, the frequency of the pulse heat treatment to 1~2 Hz, and the number of pulse heat treatments to 6~15 times. As a result, the heat of the pulse heat treatment is mainly concentrated on the surface of the sample, while the temperature change inside is small. This energy distribution feature can not only avoid overheating of the bulk phase: the internal temperature is low, reducing the risk of defect formation caused by bulk melting. It can also optimize surface reconstruction: due to the concentration of energy, the surface area can be reconstructed at local high temperature to form a more ordered crystal structure.

[0021] In addition, the rapid heating and cooling of pulse heat treatment can also effectively reduce the formation of crystal defects: Reduce impurity capture: Due to the short annealing time, impurities and defect atoms do not have enough time to diffuse into the crystal structure during the high temperature stage, thereby improving the quality of the crystal. Reduce metastable defects: During the high temperature stage, surface atoms can overcome energy barriers and migrate to more stable positions, retaining high-quality crystal structures after cooling.

[0022] Finally, the preparation method of the novel high-speed gallium oxide solar-blind ultraviolet photodetector described in the present invention is simple, requiring only magnetron sputtering, and the subsequent heat treatment method is technically stable and highly repeatable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the novel high-speed gallium oxide solar-blind ultraviolet photodetector described in the present invention; Figure 2 is a selected area electron diffraction pattern of the detector described in Example 1 of the present invention; Figure 3 Response speeds of the detectors in Example 1 (red) and Comparative Example 1 (blue); Figure 4 It is the IV diagram in Example 1 of the present invention and Comparative Example 1; Figure 5 It is the IT diagram in Example 1 of the present invention and Comparative Example 1; Figure 6Graph showing the responsivity and relative detection rate of the detector described in Example 1 of the present invention.

[0024] Among them, 1. substrate, 2. top layer, 3. middle layer, 4. bottom layer, 5. interdigitated electrodes. DETAILED DESCRIPTION

[0025] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described in detail with reference to the accompanying drawings. The described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the specific implementation methods, they shall be carried out according to the conventional conditions or the conditions provided by the manufacturer.

[0026] When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims. The terms used in the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure.

[0027] The present invention is further described in detail below in conjunction with specific embodiments. Specific implementation method one:

[0028] A novel high-speed gallium oxide solar-blind ultraviolet photodetector, characterized in that it comprises an amorphous gallium oxide thin film layer, wherein the amorphous gallium oxide thin film layer has a vertically layered crystal structure; The vertically layered crystal structure includes a top layer, a middle layer and a bottom layer, wherein the top layer has a thickness of 3 to 5 nm and a crystallinity index of 70 to 80%; the middle layer has a thickness of 0.1 to 0.3 nm and a crystallinity index of 50 to 60%; and the bottom layer has a thickness of 95 to 97 nm and a crystallinity index of 20 to 25%.

[0029] In other embodiments, the top layer of the novel high-speed gallium oxide day-blind ultraviolet photodetector includes a β-Ga2O3 crystal structure, and the volume proportion of the β-Ga2O3 crystal structure in the top layer is 80-85%; the grains in the top layer are nearly spherical, and the grain size is 12-13 nm.

[0030] In other embodiments, the transition layer of the novel high-speed gallium oxide solar-blind ultraviolet photodetector includes a β-Ga2O3 crystal structure with a volume fraction of 15% to 25%, and the remainder is an α-Ga2O3 crystal structure; the bottom layer is amorphous gallium oxide.

[0031] In other embodiments, the novel high-speed gallium oxide solar-blind ultraviolet photodetector can simultaneously meet the requirements of rise time ≤ 2.2 ms, decay time ≤ 40 μs, and spectral response rate ≥ 312.6 A·W. -1 , and the detection rate ≥1.7×10 14 Jones' detector. Specific implementation method 2:

[0032] A method for preparing a novel high-speed gallium oxide solar-blind ultraviolet photodetector based on any of the above embodiments, characterized in that it comprises the following steps: 1) Use Si / SiO2 as the substrate of the detector; 2) depositing an amorphous gallium oxide thin film on the substrate to obtain a sample to be processed; 3) performing heat treatment on the amorphous gallium oxide film prepared in step 2) to obtain an amorphous gallium oxide film layer having a vertically layered crystal structure; 4) using photolithography technology to fabricate interdigital electrodes on the amorphous gallium oxide thin film layer; 5) Using magnetron sputtering technology, a drain electrode and a source electrode are prepared on the interdigitated electrodes to obtain a detector.

[0033] In other embodiments, the heat treatment process in step 3) of the preparation method includes placing the sample to be processed on a metal substrate, performing multiple pulse heat treatments on the top of the sample to be processed, and performing cold treatment on the substrate, thereby obtaining an amorphous gallium oxide thin film layer with a vertically layered crystal structure; The specific process of the pulse heat treatment includes: the temperature of the pulse heat treatment is 900-1000° C., the duration of the pulse heat treatment is 0.5-1 s, and the frequency of the pulse heat treatment is 1-2 Hz.

[0034] In other embodiments, the deposition in step 2) of the preparation method is carried out using a magnetron sputtering process.

[0035] In other embodiments, the number of pulse heat treatments in step 3) of the preparation method is 6 to 15 times.

[0036] In other embodiments, the thickness of the amorphous gallium oxide thin film layer in the preparation method is 100-110 nm.

[0037] In other embodiments, when preparing the amorphous gallium oxide thin film in step 2) of the preparation method, an argon-oxygen mixed gas is introduced, and the gas flow rate of the argon-oxygen mixed gas is Ar:O2=28sccm:1sccm. Embodiment 1:

[0038] A new type of high-speed gallium oxide solar-blind ultraviolet photodetector, such as Figure 1 As shown, it includes a substrate 1, an amorphous gallium oxide thin film layer located on the substrate 1, and the crystalline gallium oxide thin film layer includes a bottom layer 4 close to the substrate 1, a top layer 2, and an intermediate layer 3 located between the bottom layer 4 and the top layer 2. On the top layer 2 is an interdigital electrode 5, and on the interdigital electrode 5 are also provided a source electrode and a source electrode.

[0039] In this embodiment 1, the thickness of the top layer is 3 nm, and the crystallinity index is 70-80%; the thickness of the middle layer is 0.3 nm, and the crystallinity index is 50-60%; the thickness of the bottom layer is 95-97 nm, and the crystallinity index is 20-25%.

[0040] The top layer includes a β-Ga2O3 crystal structure, and the volume fraction of the β-Ga2O3 crystal structure in the top layer is 80-85%; the grains in the top layer are nearly spherical, and the grain size is 12-13 nm. The transition layer includes a β-Ga2O3 crystal structure with a volume fraction of 15%-25%, and the remainder is an α-Ga2O3 crystal structure; the bottom layer is amorphous gallium oxide.

[0041] The preparation method specifically comprises the following steps: 1) Cleaning the substrate: Si / SiO2 is used as the substrate of the transistor. In this embodiment 1, Si is the bottom gate and thermally oxidized SiO2 with a thickness of 285 nm is the medium. The Si / SiO2 substrate is sequentially immersed in acetone for ultrasonic oscillation once and in anhydrous ethanol for ultrasonic oscillation once, each oscillation time is 20 minutes, and then stored in deionized water; 2) An amorphous gallium oxide film is grown on the substrate obtained in step 1) to obtain a sample to be processed. A-Ga2O3 film is deposited on a SiO2 substrate by magnetron RF sputtering using a custom GR-GaOX ceramic target with an O / Ga ratio of 1.19 at a substrate temperature of 25°C (RT). The deposition atmosphere is argon: oxygen = 28 sccm: 1 sccm, and the pressure is 0.15 pa.

[0042] 3) performing heat treatment on the amorphous gallium oxide film prepared in step 2) to obtain an amorphous gallium oxide thin film layer having a vertically layered crystal structure; placing the sample to be processed on a metal substrate, performing 15 pulse heat treatments on the top of the sample to be processed, and performing cold treatment on the substrate, thereby obtaining an amorphous gallium oxide thin film layer having a vertically layered crystal structure; the temperature of the pulse heat treatment is 900~1000°C, the duration of the pulse heat treatment is 0.5~1s, and the frequency of the pulse heat treatment is 1~2 Hz.

[0043] 4) Using photolithography technology, make interdigital electrodes on the amorphous gallium oxide thin film layer. Spin AZ2612 photoresist glue at a speed of 3000r / min onto the surface of the amorphous gallium oxide thin film layer, and then pre-bake it on a 200℃ heating table for 120s; after baking, use a contact mask to expose the interdigital electrode pattern on the photoresist for 3.8s; after exposure, continue to bake it for the second time on a 120℃ heating table for 120s; finally, develop it for 45s, and rinse it with deionized water after development.

[0044] 5) Using magnetron sputtering technology, drain electrodes and source electrodes are prepared on the interdigitated electrodes to obtain a detector. Using magnetron sputtering, Ti is sputtered for 20 minutes with a radio frequency source of 30W to a thickness of 20nm, and then Au is sputtered for 5 minutes with a thickness of 50nm at 20W; after the metal sputtering is completed, it is placed in acetone, anhydrous ethanol, and deionized water in turn, and the photoresist and excess Ti and Au are removed by stripping technology to obtain a patterned drain electrode and source electrode.

[0045] like Figure 2 As shown, the amorphous gallium oxide film layer achieves crystalline stratification in the vertical direction. In this Example 1, the sample was characterized by selected electron diffraction. In order to clearly understand the internal changes of the gallium oxide film during the heat treatment, the changes in crystallinity and defects in the depth of the film were studied. Transmission electron microscopy (TEM) along the cross section of the gallium oxide film layer shows the change in crystallinity. The selected area electron diffraction (SAED) image shows that after the 15th heat treatment, the surface of the film shows improved crystallinity and the appearance of β-Ga2O3 crystals. In addition, the TEM image shows that after the 15th heat treatment, there are obvious particles (yellow box) on the surface (top 5 nm, red box) compared with the interior (blue box), which is consistent with the longitudinal crystal stratification.

[0046] like Figure 3 As shown, response speed is a key factor, and the transient photocurrent response using chopped 254 nm illumination was evaluated, showing the rise time (peak photocurrent increased from 10% to 90%) and decay time (peak photocurrent decreased from 90% to 10%) of the SBPD device. By the 15th pulse process, the detector of the present invention showed a significantly faster rise and decay response, with a rise time of 2.2 ms and a decay time of 40 μs, while the pre-treated rise time was 1.7 s and decay time was 0.53 s.

[0047] like Figure 4As shown, the dark current in the detector obtained in this Example 1 can be suppressed to a level similar to that before treatment. Under 254nm illumination, the dark current shows a slight increase, but the photocurrent is significantly enhanced, indicating that the high crystallinity of the surface layer of gallium oxide has a positive effect on the performance of gallium oxide-based day-blind photodetectors. In addition, a phenomenon called "zero bias voltage shift" is observed in the dark current curve, in which the minimum current corresponds to a non-zero voltage position. This phenomenon has also been found in other Ga2O3 photodetectors and is attributed to defects that lead to carrier capture / release and ion migration / diffusion.

[0048] like Figure 5 As shown in Figure 2, the IT curve under 12 V bias was extracted. The photocurrent increased significantly to 49 μA, which is 54 times that of the untreated sample, while the dark current only increased slightly to 4.7×10 -9 A.

[0049] like Figure 6 As shown, the detector in this embodiment 1 has a maximum R λ 312.6 A·W respectively -1 and 1.7×10 14 Jones, which are 53 times and nearly 100 times higher than the detector in Comparative Example 1, respectively. Embodiment 2:

[0050] The only difference between Example 2 and Example 1 is that the thickness of the top layer is 4 nm. Embodiment 3:

[0051] The only difference between Example 3 and Example 1 is that the thickness of the top layer is 5 nm.

[0052] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the amorphous gallium oxide film in Example 1 is not subjected to a heat treatment process, and the interdigital electrodes are directly made on the amorphous gallium oxide film layer using photolithography technology. Figure 3 As shown, Figure 4 As shown, all IV characteristics of the photodetector in Comparative Example 1 are in the dark and under sunshade UV irradiation (254 nm, 395 μW / cm 2 ) will undergo significant changes. Figure 5 As shown, when the initial dark current is 5×10 -10 A has only a photocurrent of 0.9 μA. Figure 6 As shown, R λ and D* are 5.8 A·W respectively -1 and 8.23×10 12 Jones.

[0053] Comparative Example 2: The only difference between Comparative Example 2 and Example 1 is that the thickness of the top layer is 2 nm. If the top layer is too thin, on the one hand, the light absorption efficiency will be reduced, thereby reducing the generation of photogenerated carriers, and on the other hand, the ultraviolet light response will be reduced, and the dark current cannot be effectively suppressed, resulting in a decrease in detection performance.

[0054] Comparative Example 3: The only difference between this comparative example 3 and example 1 is that the thickness of the top layer is 6 nm. When the thickness of the top layer is too thick, the depletion layer is too wide, which may cause the dark current to increase, affect the sensitivity of the device, cause the photocurrent to decrease, and increase the dark current, thereby reducing the light-to-dark current ratio and affecting the detection performance of the device. At the same time, the top layer is too thick, which slows down the response speed because the transmission path of the carrier becomes longer, resulting in a longer recovery transient time.

[0055] Comparative Example 4: The only difference between this comparative example 4 and example 1 is that the crystallinity index of the top layer is 50-60%. Too low crystallinity of the top layer will lead to reduced light absorption efficiency, thereby reducing the photocurrent. And the light-to-dark current ratio (PDCR) is also low, indicating that the current differentiation under light and dark conditions is not obvious enough, affecting the sensitivity of the detector. In addition, the top layer with lower crystallinity contains more defects such as oxygen vacancies or gallium vacancies, which will capture carriers as trap centers, reducing carrier mobility and lifetime. These defects may also lead to an increase in non-radiative recombination of photogenerated carriers, further reducing the photoelectric performance.

[0056] Comparative Example 5: The only difference between this comparative example 5 and example 1 is that the crystallinity index of the top layer is 85-90%. Too high crystallinity of the top layer means that the crystallization quality of the film is significantly improved, but it may also lead to an increase in defects such as oxygen vacancies. Oxygen vacancies are deep energy level defects in gallium oxide, which can act as electron trap centers and affect the transport of carriers. Too high crystallinity may lead to excessive defect concentration, which in turn reduces carrier mobility. Moreover, too high crystallinity will increase the dark current, resulting in a decrease in the light-to-dark current ratio. It will also cause the carrier transmission path to become longer and the response speed to become slower. In addition, too high crystallinity will also cause the bandgap width of the film to change, the absorption edge to blue-shift, and affect its absorption efficiency for light of a specific wavelength.

[0057] The present invention is described by the above specific embodiments, and those skilled in the art should understand that various changes and equivalent substitutions can be made to the present invention without departing from the scope of the present invention. The parts not described in detail in the present specification are well-known technologies to those skilled in the art. In addition, various modifications can be made to the present invention for specific situations or specific circumstances without departing from the scope of the present use. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all implementation methods falling within the scope of the claims of the present invention.

Claims

1. A new type of high-speed gallium oxide solar-blind ultraviolet photodetector, characterized in that: The amorphous gallium oxide thin film layer includes an amorphous gallium oxide thin film layer having a vertically layered crystal structure; The vertically layered crystal structure includes a top layer, a middle layer and a bottom layer, wherein the top layer has a thickness of 3 to 5 nm and a crystallinity index of 70 to 80%; the middle layer has a thickness of 0.1 to 0.3 nm and a crystallinity index of 50 to 60%; and the bottom layer has a thickness of 95 to 97 nm and a crystallinity index of 20 to 25%.

2. The novel high-speed gallium oxide solar-blind ultraviolet photodetector according to claim 1 is characterized in that: The top layer includes a β-Ga2O3 crystal structure, and the volume of the β-Ga2O3 crystal structure in the top layer accounts for 80-85%; the grains in the top layer are nearly spherical, and the grain size is 12-13 nm.

3. The novel high-speed gallium oxide solar-blind ultraviolet photodetector according to claim 1, characterized in that: The transition layer includes a β-Ga2O3 crystal structure with a volume fraction of 15% to 25%, and the remainder is an α-Ga2O3 crystal structure; the bottom layer is amorphous gallium oxide.

4. The novel high-speed gallium oxide solar-blind ultraviolet photodetector according to claim 1, characterized in that: The novel high-speed gallium oxide solar-blind ultraviolet photodetector can simultaneously meet the requirements of rise time ≤ 2.2 ms, decay time ≤ 40 μs, and spectral response rate ≥ 312.6 A·W. -1 , and the detection rate ≥1.7×10 14 Jones' detector.

5. A method for preparing a novel high-speed gallium oxide solar-blind ultraviolet photodetector according to any one of claims 1 to 4, characterized in that: The steps include: 1) Use Si / SiO2 as the substrate of the detector; 2) depositing an amorphous gallium oxide thin film on the substrate to obtain a sample to be processed; 3) performing heat treatment on the amorphous gallium oxide film prepared in step 2) to obtain an amorphous gallium oxide film layer having a vertically layered crystal structure; 4) using photolithography technology to fabricate interdigital electrodes on the amorphous gallium oxide thin film layer; 5) Using magnetron sputtering technology, a drain electrode and a source electrode are prepared on the interdigitated electrodes to obtain a detector.

6. The preparation method according to claim 5, characterized in that: The heat treatment process in step 3) includes placing the sample to be processed on a metal substrate, performing multiple pulse heat treatments on the top of the sample to be processed, and performing cold treatment on the substrate, thereby obtaining an amorphous gallium oxide thin film layer with a vertically layered crystal structure; The specific process of the pulse heat treatment includes: the temperature of the pulse heat treatment is 900-1000° C., the duration of the pulse heat treatment is 0.5-1 s, and the frequency of the pulse heat treatment is 1-2 Hz.

7. The preparation method according to claim 6, characterized in that: The deposition in step 2) is carried out by a magnetron sputtering process.

8. The preparation method according to claim 7, characterized in that: The number of pulse heat treatment in step 3) is 6 to 15 times.

9. The preparation method according to claim 8, characterized in that: The thickness of the amorphous gallium oxide thin film layer is 100-110 nm.

10. The preparation method according to claim 9, characterized in that: When preparing the amorphous gallium oxide film in step 2), an argon-oxygen mixed gas is introduced, and the gas flow rate of the argon-oxygen mixed gas is Ar:O2=28sccm:1sccm.

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