A photoelectric detector and a preparation method thereof
By combining magnetron sputtering and CVD, large-size two-dimensional MoS2 was grown on GaN, and a heterojunction was constructed by photolithography and Ar plasma etching. This solved the fabrication problem of two-dimensional MoS2/GaN heterojunction photodetectors in traditional methods, and achieved high responsivity and wide-spectral detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2023-10-31
- Publication Date
- 2026-07-10
AI Technical Summary
Traditional methods make it difficult to fabricate large-size two-dimensional MoS2 on GaN, and the performance of two-dimensional MoS2/GaN heterojunction photodetectors is limited, making it difficult to achieve high responsivity and wide-spectral detection.
Large-size two-dimensional MoS2 was grown on GaN using magnetron sputtering combined with CVD technology, and the two-dimensional MoS2 was patterned by photolithography and Ar plasma etching to construct a two-dimensional MoS2/GaN heterojunction photodetector.
The fabrication of high-performance photodetectors was achieved, improving the collection and transport of photogenerated carriers, enhancing responsivity and response speed, and enabling broadband detection.
Smart Images
Figure CN117393649B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor photodetector technology, and in particular to a photodetector and its fabrication method. Background Technology
[0002] Group III nitride semiconductor materials possess excellent optical, electrical, thermal, chemical, and mechanical properties, and are currently widely used in group III nitride optoelectronic devices and power devices. GaN, as one of the research hotspots in third-generation semiconductor materials, exhibits high electron mobility, good thermal stability, and good chemical stability, making it suitable for use as a photodetector for ultraviolet detection.
[0003] In recent years, two-dimensional materials have demonstrated superior electrical, optical, and mechanical properties compared to bulk materials, leading to their significant potential in catalysis, microelectronics, ion storage, and optoelectronics. Molybdenum disulfide (MoS2), one of the most popular two-dimensional materials, possesses a band gap of 1.6 eV and has exhibited excellent performance in photodetector fabrication. However, the small size and random growth of two-dimensional MoS2 grown on GaN using traditional CVD methods hinder large-scale device fabrication, thus limiting the further development of two-dimensional MoS2 / GaN. Summary of the Invention
[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the present invention aims to provide a method for fabricating a photodetector. A magnetron sputtering device combined with CVD is used to grow a large-size two-dimensional MoS2 on GaN. The two-dimensional MoS2 is patterned by using photolithography combined with Ar plasma etching to fabricate a high-performance photodetector. The method is simple to operate and suitable for the large-scale production of photodetectors based on two-dimensional MoS2.
[0005] Another objective of this invention is to provide a photodetector prepared by the above-mentioned method, which constructs a two-dimensional MoS2 / GaN heterojunction detector. By utilizing the two-dimensional MoS2 material to form a heterojunction with GaN, the collection and transport of photogenerated carriers are effectively promoted, the responsivity and response speed of the material are improved, and a broadband detector is realized by utilizing the smaller bandgap of two-dimensional MoS2 compared to GaN.
[0006] The objective of this invention is achieved through the following technical solution:
[0007] A method for fabricating a photodetector includes the following steps:
[0008] (1) After thoroughly cleaning the GaN / AlGaN buffer layer / substrate, the GaN epitaxial wafer with separation mesa is obtained by ICP etching.
[0009] (2) The GaN epitaxial wafer with the separation mesa is transferred to a magnetron sputtering device to sputter a thin layer of metal Mo to obtain a Mo / GaN / AlGaN buffer layer / substrate:
[0010] (3) The Mo / GaN / AlGaN buffer layer / substrate was transferred to a CVD furnace, and S powder precursor was placed in it for high-temperature sulfidation to obtain a two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate:
[0011] (4) The two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate is subjected to photoresist coating, exposure and development to obtain a two-dimensional MoS2 patterned region; the two-dimensional MoS2 patterned region is protected by photoresist coating, and then Ar plasma etching is performed to obtain a two-dimensional MoS2 patterned two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate.
[0012] (5) An Au electrode is prepared on a two-dimensional MoS2, and a Ti / Au electrode is prepared on GaN to obtain a photodetector; the Ti / Au electrode consists of a Ti metal layer and an Au metal layer from bottom to top.
[0013] Preferably, the specific process for sputtering a thin layer of Mo metal in step (2) is as follows:
[0014] The sputtering pressure was 0.4-0.8 Pa, the sputtering power was 30-50 W, the sample temperature was 100-200 ℃, the gas atmosphere was Ar, the growth time was 3 s-15 s, and the thickness of the sputtered Mo metal was 1-6 nm.
[0015] Preferably, the high-temperature vulcanization process described in step (3) is as follows:
[0016] The growth distance is 15-20cm, the air pressure is maintained at atmospheric pressure, and the growth is carried out in an N2 atmosphere with an N2 flow rate of 5-100 sccm. The growth temperature is 650-750℃, the heating rate is 5-10℃ / min, the cooling rate is 5-10℃ / min, and the holding time is 25-30min.
[0017] Preferably, the Ar plasma etching process in step (4) is as follows:
[0018] The etching time is 30-120 min, the plasma intensity is 100-200 W, and after etching, the photoresist is removed by soaking in hot acetone for 0.8-1 h.
[0019] Preferably, the process of spin coating, exposure, and development described in step (4) is as follows:
[0020] First, spin-coat positive photoresist for 50-60 seconds at a spin speed of 3000-4500 rpm, then pre-bake at 85-105℃ for 2-3 minutes, expose to deep ultraviolet light for 30-40 seconds, and develop for 60-65 seconds.
[0021] Preferably, step (5) involves fabricating an Au electrode on two-dimensional MoS2, specifically as follows:
[0022] The two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate obtained in step (4) was homogenized for 50-60s; then the sample was heated at 85-105℃ for 2-3min; the dried sample was further exposed to a deep ultraviolet light source for 30-40s, with the exposed area being the Au electrode; then the photolithographically etched sample was developed for 60-65s, and the resulting sample was transferred to an electron beam evaporation device to prepare the Au metal layer, and then immersed in acetone at 70-80℃ for 0.8-1h to remove the Au metal layer in the photoresist area.
[0023] Preferably, step (5) of fabricating the Ti / Au electrode on GaN specifically involves:
[0024] After preparing the Au electrode, the sample is homogenized for 50-60 seconds; then the sample is heated at 85-105℃ for 2-3 minutes; the dried sample is further exposed to a deep ultraviolet light source for 30-40 seconds, with the exposed area being the Au electrode; then the photolithographically etched sample is developed for 60-65 seconds, and the resulting sample is transferred to an electron beam evaporation device to sequentially deposit metallic Ti and metallic Au, and then immersed in acetone at 70-80℃ for 0.8-1 hours to remove the metal layer in the photoresist area.
[0025] A photodetector, fabricated by the aforementioned photodetector fabrication method, comprises, from bottom to top, a substrate, an AlGaN buffer layer, a GaN layer, a two-dimensional MoS2 layer, and an Au electrode; the two-dimensional MoS2 layer partially covers the GaN layer, and a Ti / Au electrode is disposed on the GaN layer.
[0026] Preferably, the GaN layer has a thickness of 200-500 nm; the two-dimensional MoS2 layer has a thickness of 1-10 nm; the Au electrode has a thickness of 100-200 nm; and the Ti metal layer in the Ti / Au electrode has a thickness of 30-60 nm and the Au metal layer has a thickness of 80-150 nm.
[0027] Preferably, the substrate is a Si, SiC, or sapphire substrate.
[0028] Preferably, the ICP etching in step (1) specifically involves an etching thickness of 200-500 nm.
[0029] Preferably, the thickness of the thin layer of metal Mo is 1-6 nm.
[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0031] (1) The method for fabricating the photodetector of the present invention uses magnetron sputtering equipment combined with CVD to achieve the growth of large-size two-dimensional MoS2 on GaN, and uses photolithography combined with Ar plasma etching to achieve the patterning of two-dimensional MoS2, thereby fabricating a high-performance photodetector. The method is simple to operate and suitable for large-scale production of photodetectors based on two-dimensional MoS2.
[0032] (3) The photodetector fabrication method of the present invention involves Ar plasma etching after CVD high-temperature sulfurization to prepare two-dimensional MoS2, thereby achieving patterned fabrication of MoS2 and avoiding the phenomenon of random diffusion of MoS2 at high temperature caused by traditional etching followed by CVD high-temperature sulfurization, which is beneficial for further photodetector fabrication. (4) The present invention constructs a two-dimensional MoS2 / GaN heterojunction detector, which utilizes the two-dimensional MoS2 material to form a heterojunction with GaN, effectively promoting the collection and transport of photogenerated carriers, improving responsivity and response speed, and utilizing the smaller bandgap of two-dimensional MoS2 than GaN to realize a broadband detector. Attached Figure Description
[0033] Figure 1 This is a schematic cross-sectional view of a photodetector prepared according to an embodiment of the present invention.
[0034] Figure 2 A top view of a photodetector prepared according to an embodiment of the present invention.
[0035] Figure 3 AFM morphology image of metallic Mo prepared for an embodiment of the present invention.
[0036] Figure 4 Two-dimensional MoS2 Raman spectra after Ar plasma etching, as shown in the embodiments of the present invention.
[0037] Figure 5 Two-dimensional MoS2 edge map after Ar plasma etching for an embodiment of the present invention.
[0038] Figure 6 The dark current and photocurrent at 365 nm of the photodetector prepared for an embodiment of the present invention.
[0039] Figure 7 The spectral response of the photodetector prepared according to an embodiment of the present invention.
[0040] Figure 8The response time of the photodetector prepared for an embodiment of the present invention was tested under 365 nm illumination at 0 V. Detailed Implementation
[0041] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.
[0042] Example 1:
[0043] like Figure 1-2 As shown, the photodetector in this embodiment includes a substrate 1, an AlGaN buffer layer 2, a GaN layer 3, a two-dimensional MoS2 layer 4, an Au electrode 5, and a Ti / Au electrode 6. The two-dimensional MoS2 layer partially covers the GaN layer, and the Ti / Au electrode is disposed on the GaN layer. The two-dimensional MoS2 and GaN form a heterojunction, creating a built-in electric field.
[0044] The photodetector fabrication method in this embodiment includes the following steps:
[0045] Step 1: The GaN / AlGaN buffer layer / substrate is ultrasonically treated in acetone, anhydrous ethanol and deionized water for 20 minutes in sequence, with an ultrasonic power of 100 kHz. Then it is dried with nitrogen to clean the sample surface.
[0046] Step 2: The sample obtained in Step 1 is subjected to homogenization with a positive resist at a rotation speed of 3700 rpm for 60 min; the sample is then dried at 95°C for 2 min; the dried sample is then exposed to the non-mesa area for 40 s; the photolithographically etched sample is then developed for 60 s; and finally etched by ICP to a thickness of 300 nm.
[0047] Step 3: Place the sample obtained in Step 2 into a magnetron sputtering apparatus for Mo sputtering. Set the sputtering power to 40W, sample disk temperature to 180℃, sputtering pressure to 0.5Pa, gas atmosphere to Ar, and sputtering time to 5s. Figure 3 The image shows the AFM topography of the sputtered metal, indicating that a uniform distribution of the Mo precursor on GaN has been achieved, which is beneficial for obtaining a uniform two-dimensional MoS2.
[0048] Step 4: Transfer the sample obtained in Step 3 to a CVD tube furnace, add 200 mg of sulfur powder as a precursor, maintain the distance between the precursor and the sample at 15 cm, introduce 10 sccm of nitrogen gas, keep the gas pressure at atmospheric pressure, raise the temperature to 680 °C at a heating rate of 10 °C / min, hold for 30 min, and then lower the temperature to room temperature at a cooling rate of 10 °C / min.
[0049] Step 5: The sample obtained in Step 4 is subjected to homogenization using a positive adhesive at a rotation speed of 3700 rpm for 60 seconds. The sample is then dried at 95°C for 2 minutes. The dried sample is further exposed to light, with the mask area being... Figure 2 The two-dimensional MoS2 layer was exposed for 40 seconds; the photolithographically etched sample was then developed for 60 seconds.
[0050] Step 6: Perform Ar plasma etching on the sample obtained in Step 5. The etching power is 200W and the etching time is 60min. Figure 4 The Raman spectrum of two-dimensional MoS2 after etching is shown, indicating that two-dimensional MoS2 was obtained through the above process; Figure 5 The etched 2D MoS2 edge map is shown, indicating that a flat MoS2 edge was obtained, which is beneficial for the patterned fabrication of the device.
[0051] Step 7: The sample obtained in Step 6 is homogenized using a positive gel at a rotation speed of 3700 rpm for 60 seconds. The sample is then dried at 95°C for 2 minutes. The dried sample is further exposed to sunlight, with the exposed area being... Figure 2 Au electrode 5 was exposed for 40 seconds; the photolithographically etched sample was then developed for 60 seconds.
[0052] Step 8: Transfer the sample obtained in step 7 to an electron beam evaporation device to fabricate a metal Au electrode. The metal Au deposition thickness is 150 nm.
[0053] Step 9: Transfer the sample obtained in Step 8 to a beaker, pour in an appropriate amount of acetone, and soak at 80°C for 1 hour to remove the photoresist.
[0054] Step 10: The sample obtained in Step 9 is homogenized using a positive gel at a rotation speed of 3700 rpm for 60 minutes. The sample is then dried at 95°C for 2 minutes. The dried sample is further exposed to sunlight, with the exposed area being... Figure 2 The Ti / Au electrode 6 was exposed for 40 seconds; the photolithographically etched sample was then developed for 60 seconds.
[0055] Step 11: Transfer the sample obtained in step 10 to an electron beam evaporation device to sequentially deposit metallic Ti and metallic Au. The thickness of metallic Ti is 30 nm and the thickness of metallic Au is 120 nm.
[0056] Step 12: Transfer the sample obtained in Step 11 to a beaker, pour in an appropriate amount of acetone, and soak at 80°C for 1 hour to remove the photoresist and obtain the detector;
[0057] Step 13: Test the detector obtained in Step 12.
[0058] Figure 6 The dark current and photocurrent at 365nm of the two-dimensional MoS2 / GaN heterojunction detector obtained in this embodiment can be seen to show that the detector achieves low dark current and high sensitivity and responsivity. Figure 7 The spectral response of the fabricated detector shows that the device exhibits response peaks in the range of 365 nm to 650 nm, indicating that the device possesses broad spectral response characteristics. Figure 8 The response time of the fabricated detector was measured under 365nm illumination at 0V. It can be seen that the device achieves self-driving under 0V conditions and has an ultra-fast response time.
[0059] Example 2:
[0060] The photodetector of this embodiment is fabricated by the following steps:
[0061] Step 1: The GaN / AlGaN buffer layer / substrate is ultrasonically treated in acetone, anhydrous ethanol and deionized water for 15 minutes in sequence, with an ultrasonic power of 100 kHz. Then it is dried with nitrogen to clean the sample surface.
[0062] Step 2: The sample obtained in Step 1 is subjected to homopolymer coating. The homopolymer coating rate is 4000 rpm and the time is 60 s. The sample is then dried at 95°C for 2 min. The dried sample is then exposed to the non-device mesa area for 40 s. The photolithographically etched sample is then developed for 60 s and then etched by ICP with a thickness of 300 nm.
[0063] Step 3: Place the sample obtained in Step 2 into a magnetron sputtering device to sputter metallic Mo. Set the sputtering power to 50W, sample disk temperature to 150℃, sputtering pressure to 0.5Pa, gas atmosphere to Ar, and sputtering time to 10s.
[0064] Step 4: Transfer the sample obtained in Step 3 to a CVD tube furnace, add 400 mg of sulfur powder as a precursor, maintain the distance between the precursor and the sample at 20 cm, introduce 20 sccm of nitrogen gas, keep the gas pressure at atmospheric pressure, raise the temperature to 700 °C at a heating rate of 15 °C / min, hold for 30 min, and then lower the temperature to room temperature at a cooling rate of 10 °C / min.
[0065] Step 5: The sample obtained in Step 4 is homogenized using a positive adhesive at a rotation speed of 4000 rpm for 55 seconds. The sample is then dried at 85°C for 3 minutes. Finally, the dried sample is exposed to light, with the mask area being... Figure 2 The two-dimensional MoS2 layer was exposed for 30 seconds; the photolithographically etched sample was then developed for 60 seconds.
[0066] Step 6: Perform Ar plasma etching on the sample obtained in Step 5. The etching power is 100W and the etching time is 90min.
[0067] Step 7: The sample obtained in Step 6 is homogenized using a positive gel at a rotation speed of 4000 rpm for 60 seconds. The sample is then dried at 95°C for 2 minutes. The dried sample is further exposed to sunlight, with the exposed area being... Figure 2 Au electrode 5 was exposed for 40 seconds; the photolithographically etched sample was then developed for 60 seconds.
[0068] Step 8: Transfer the sample obtained in step 7 to an electron beam evaporation device to fabricate a metal Au electrode with a metal thickness of 180 nm.
[0069] Step 9: Transfer the sample obtained in Step 8 to a beaker, pour in an appropriate amount of acetone, and soak at 80°C for 1 hour to remove the photoresist.
[0070] Step 10: The sample obtained in Step 9 is homogenized using a positive gel at a rotation speed of 3700 rpm for 60 seconds. The sample is then dried at 95°C for 2 minutes. The dried sample is further exposed to sunlight, with the exposed area being... Figure 2 The Ti / Au electrode 6 was exposed for 40 seconds; the photolithographically etched sample was then developed for 60 seconds.
[0071] Step 11: Transfer the sample obtained in step 10 to an electron beam evaporation device to sequentially deposit metallic Ti and metallic Au. The thickness of metallic Ti is 50 nm and the thickness of metallic Au is 110 nm.
[0072] Step 12: Transfer the sample obtained in Step 11 to a beaker, pour in an appropriate amount of acetone, and soak at 85°C for 1 hour to remove the photoresist and obtain the detector;
[0073] Step 13: Test the detector obtained in Step 12. The results show that the device has a wide spectral response; it exhibits self-driving under 0V conditions and has an ultrafast response time.
[0074] Example 3:
[0075] The photodetector of this embodiment is fabricated by the following steps:
[0076] Step 1: The GaN / AlGaN buffer layer / substrate is ultrasonically treated in acetone, anhydrous ethanol and deionized water for 20 minutes in sequence, with an ultrasonic power of 100 kHz. Then it is dried with nitrogen to clean the sample surface.
[0077] Step 2: The sample obtained in Step 1 is subjected to homopolymer coating. The homopolymer coating rate is 4500 rpm and the time is 50 s. The sample is then dried at 85°C for 3 min. The dried sample is then exposed to the non-device mesa area for 30 s. The photolithographically etched sample is then developed for 50 s and then etched by ICP with a thickness of 300 nm.
[0078] Step 3: Place the sample obtained in Step 2 into a magnetron sputtering device to sputter metallic Mo. Set the sputtering power to 30W, the sample disk temperature to 200℃, the sputtering pressure to 0.8Pa, the gas atmosphere to Ar, and the sputtering time to 15s.
[0079] Step 4: Transfer the sample obtained in Step 3 to a CVD tube furnace, add 600 mg of sulfur powder as a precursor, maintain the distance between the precursor and the sample at 20 cm, introduce 50 sccm of nitrogen gas, keep the gas pressure at atmospheric pressure, raise the temperature to 750 °C at a heating rate of 10 °C / min, hold for 30 min, and then lower the temperature to room temperature at a cooling rate of 10 °C / min.
[0080] Step 5: The sample obtained in Step 4 is subjected to homogenization using a positive adhesive at a rotation speed of 4500 rpm for 50 seconds. The sample is then dried at 85°C for 3 minutes. The dried sample is further exposed to light, with the mask area being... Figure 2 The two-dimensional MoS2 layer was exposed for 30 seconds; the photolithographically etched sample was then developed for 50 seconds.
[0081] Step 6: Perform Ar plasma etching on the sample obtained in Step 5. The etching power is 200W and the etching time is 50min.
[0082] Step 7: The sample obtained in Step 6 is homogenized using a positive gel at a rotation speed of 4500 rpm for 50 seconds. The sample is then dried at 85°C for 3 minutes. The dried sample is further exposed to sunlight, with the exposed area being... Figure 2 The Ti / Au electrode 6 was exposed for 30 seconds; the photolithographically etched sample was then developed for 50 seconds.
[0083] Step 8: Transfer the sample obtained in step 7 to an electron beam evaporation device to fabricate a Ti / Au metal electrode with a thickness of 30 / 110 nm for Ti / Au metal.
[0084] Step 9: Transfer the sample obtained in Step 8 to a beaker, pour in an appropriate amount of acetone, and soak at 80°C for 1 hour to remove the photoresist.
[0085] Step 10: The sample obtained in Step 9 is homogenized using a positive gel at a rotation speed of 4500 rpm for 50 seconds. The sample is then dried at 85°C for 3 minutes. The dried sample is further exposed to sunlight, with the exposed area being... Figure 2 Au electrode 5 was exposed for 30 seconds; the photolithographically etched sample was then developed for 50 seconds.
[0086] Step 11: Transfer the sample obtained in step 10 to an electron beam evaporation device to deposit metallic Au. The thickness of the metallic Au deposition is 140 nm.
[0087] Step 12: Transfer the sample obtained in Step 11 to a beaker, pour in an appropriate amount of acetone, and soak at 85°C for 1 hour to remove the photoresist and obtain the detector;
[0088] Step 13: Test the detector obtained in Step 12. The results show that the device has a wide spectral response; it exhibits self-driving under 0V conditions and has an ultrafast response time.
[0089] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for fabricating a photodetector, characterized in that, Includes the following steps: (1) After thoroughly cleaning the GaN / AlGaN buffer layer / substrate, an ICP etching process is used to obtain a GaN epitaxial wafer with a separation mesa. (2) The GaN epitaxial wafer with the separation mesa is transferred to a magnetron sputtering device to sputter a thin layer of metal Mo to obtain a Mo / GaN / AlGaN buffer layer / substrate; The specific process for sputtering a thin layer of metallic Mo is as follows: sputtering pressure is 0.4-0.8 Pa, sputtering power is 30-50 W, sample temperature is 100-200℃, gas atmosphere is Ar atmosphere, growth time is 3s-15s, and sputtered metallic Mo thickness is 1-6 nm. (3) Transfer the Mo / GaN / AlGaN buffer layer / substrate to a CVD furnace, place the S powder precursor in it, and perform high-temperature sulfidation to obtain a two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate; The high-temperature vulcanization process is as follows: the growth distance is 15-20cm, the air pressure is maintained at atmospheric pressure, the growth is carried out in an N2 atmosphere, the N2 flow rate is 5-100sccm, the growth temperature is 650-750℃, the heating rate is 5-10℃ / min, the cooling rate is 5-10℃ / min, and the holding time is 25-30min. (4) The two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate is subjected to photoresist coating, exposure and development to obtain a two-dimensional MoS2 patterned region; the two-dimensional MoS2 patterned region is protected by photoresist coating, and then Ar plasma etching is performed to obtain a two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate with two-dimensional MoS2 pattern. The specific process of Ar plasma etching is as follows: etching time is 30-120 min, plasma intensity is 100-200 W, and after etching, the photoresist is removed by soaking in hot acetone for 0.8-1 h. (5) An Au electrode is fabricated on a two-dimensional MoS2 substrate, and a Ti / Au electrode is fabricated on a GaN substrate to obtain a photodetector; the Ti / Au electrode consists of a Ti metal layer and an Au metal layer from bottom to top. The thickness of the GaN layer is 200-500 nm; the thickness of the two-dimensional MoS2 layer is 1-10 nm; the thickness of the Au electrode is 100-200 nm; the thickness of the Ti metal layer in the Ti / Au electrode is 30-60 nm, and the thickness of the Au metal layer is 80-150 nm. The photodetector is self-driven under 0V conditions.
2. The method for fabricating a photodetector according to claim 1, characterized in that, Step (4) involves spin coating, exposure, and development. The specific process is as follows: First, spin coating positive photoresist for 50-60 seconds using a spin coater at a speed of 3000-4500 rpm. Then, pre-bake the photoresist by heating it at 85-105℃ for 2-3 minutes, expose it to a deep ultraviolet light source for 30-40 seconds, and develop it for 60-65 seconds.
3. The method for fabricating a photodetector according to claim 1, characterized in that, Step (5) involves preparing an Au electrode on a two-dimensional MoS2 substrate. Specifically, the two-dimensional MoS2 / GaN / AlGaN buffer layer / substrate obtained in step (4) is homogenized for 50-60 seconds. The sample is then heated at 85-105℃ for 2-3 minutes. The dried sample is then exposed to a deep ultraviolet light source for 30-40 seconds, with the exposed area being the Au electrode. The photolithographically etched sample is then developed for 60-65 seconds. The resulting sample is transferred to an electron beam evaporation device to prepare an Au metal layer. Finally, the sample is immersed in acetone at 70-80℃ for 0.8-1 hours to remove the Au metal layer from the photoresist area.
4. The method for fabricating a photodetector according to claim 1, characterized in that, Step (5) involves preparing a Ti / Au electrode on GaN, specifically: homogenizing the sample after preparing the Au electrode for 50-60 seconds; then heating the sample at 85-105℃ for 2-3 minutes; further exposing the dried sample to a deep ultraviolet light source for 30-40 seconds, with the exposed area being the Au electrode; then developing the photolithographically etched sample for 60-65 seconds, transferring the resulting sample to an electron beam evaporation device to sequentially deposit metallic Ti and metallic Au, and then immersing it in acetone at 70-80℃ for 0.8-1 hours to remove the metal layer in the photoresist area.
5. A photodetector, characterized in that, The photodetector is prepared by the method described in any one of claims 1 to 4, and comprises, from bottom to top, a substrate, an AlGaN buffer layer, a GaN layer, a two-dimensional MoS2 layer, and an Au electrode; the two-dimensional MoS2 layer partially covers the GaN layer, and a Ti / Au electrode is disposed on the GaN layer.
6. The photodetector according to claim 5, characterized in that, The substrate is a Si, SiC, or sapphire substrate.