Application of two-dimensional Gase film in photoelectric detector

Abstract

The invention relates to the technical field of photoelectric materials, and particularly discloses an application of a two-dimensional GeSe film in a photoelectric detector, the photoelectric detector comprises a substrate layer, an insulating layer arranged on the substrate layer, a heterostructure formed on the insulating layer, and electrodes respectively connected with a source electrode and a drain electrode of the heterostructure, the heterostructure at least comprises a layer of two-dimensional GeSe thin film, the thin film is deposited on a SiO2 / Si substrate through a physical vapor deposition method, the two-dimensional GeSe thin film has high crystal quality, uniform diameter and good consistency, and has small pressure stress or lattice distortion, and when the thin film is applied to a photoelectric detector, the photoelectric detector has good photoelectric detector performance. The detection rate and the sensitivity of the detector can be obviously improved, and the response time and the recovery time are obviously shortened.

Description

Technical Field

[0001] The invention belongs to the field of photoelectric materials, and in particular relates to the application of a two-dimensional Gese film in a photoelectric detector. Background Art

[0002] Photodetectors are important optical information sensing devices that can directly convert optical signals into modulated electrical signals. They are widely used in optical communications, imaging, sensing, night vision and other fields. As a functional semiconductor device that converts optical signals into electrical signals, photodetectors need to measure their detection performance through some major performance parameters, such as spectral responsivity, quantum efficiency, response time, stability, etc. With the continuous development of nanotechnology and materials science, two-dimensional materials have become a research hotspot in the field of semiconductor devices and new optoelectronic technologies due to their unique physical, chemical and optoelectronic properties. Since the discovery of graphene, various new two-dimensional materials have emerged one after another, such as molybdenum disulfide (MoS2), black phosphorus (BP) and indium selenide (InSe). The research on these materials has further broadened the application range of low-dimensional materials and provided a theoretical and experimental basis for the construction of high-performance electronic and optoelectronic devices.

[0003] As an important member of the IV-VI group of compounds, two-dimensional GeSe thin films exhibit significant structural anisotropy, excellent environmental stability, a wide range of optical absorption coefficients from near-infrared to ultraviolet regions, suitable band gaps, and high carrier mobility, making GeSe show great application potential in optoelectronic devices such as photodetectors, field-effect transistors, and solar cells. There are many methods for preparing two-dimensional GeSe thin films, including mechanical exfoliation, liquid phase exfoliation, rapid thermal sublimation (RTS), physical vapor deposition (PVD), and chemical vapor deposition (CVD). The optoelectronic properties of GeSe thin films are affected by many factors, including the thickness, crystal structure, defect density, and substrate type of the film. Studies have shown that the thickness of the film has an important influence on the light absorption characteristics. As the thickness of the film decreases, the light absorption efficiency usually increases. In addition, the crystal orientation and defect density of the GeSe film also have a significant effect on its optoelectronic properties. High-quality crystal structures can provide better carrier mobility, thereby improving the response speed and sensitivity of the device. Therefore, optimizing the preparation process of GeSe thin film materials to provide a high-quality two-dimensional GeSe film is of great significance for improving the performance of photodetectors. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide an application of a two-dimensional GeSe film in a photodetector. The two-dimensional GeSe film is prepared by deposition on a SiO2 / Si substrate by physical vapor deposition. It has high crystal quality, uniform diameter, good consistency, and small compressive stress or lattice distortion.

[0005] The purpose of the present invention can be achieved through the following technical solutions: The application of two-dimensional GeSe thin film in photodetector, the photodetector includes a substrate layer, an insulating layer arranged on the substrate layer, a heterostructure formed on the insulating layer, and electrodes respectively connected to the source and drain of the heterostructure, wherein the heterostructure includes at least one layer of two-dimensional GeSe thin film, and the two-dimensional GeSe thin film is deposited and prepared on a SiO2 / Si substrate by physical vapor deposition. The two-dimensional GeSe thin film has high crystal quality, uniform diameter, good consistency, and small compressive stress or lattice distortion.

[0006] Preferably, the GeSe film has a photoelectric sensitivity of 28.28, a response time of 14 ms, and a recovery time of 43 ms at a wavelength of 880 nm.

[0007] Preferably, the method for preparing a two-dimensional GeSe thin film comprises the following steps: A. Accurately weigh a certain amount of GeSe powder and place it evenly in a quartz boat, and then place the quartz boat in the center of the quartz tube; B. The SiO2 / Si substrate was ultrasonically cleaned for 20-30 minutes and then dried in a nitrogen atmosphere. The cleaned substrate was placed downstream of the heating zone to ensure that the distance between the substrate and the bottom of the quartz tube was 3-5 cm. C. Use a vacuum pump to evacuate the inside of the quartz tube to a vacuum state, and then flush the quartz tube with argon gas at a flow rate of 440-460 sccm for 10 minutes; D. While maintaining the argon injection, heat the center of the quartz tube to 550~570℃ at a heating rate of 20℃ / min, and then keep the temperature for reaction for 60~80min; E. After the reaction is completed, wait for the system to cool naturally to room temperature and then take out the substrate. A layer of black GeSe film is evenly grown on the substrate.

[0008] Preferably, the GeSe powder in step A has a particle size of 160 mesh, a purity of 99.99%, and a mass of 20-30 mg.

[0009] Preferably, in step B, a mixed solution of CCl4 and acetone, ethanol and deionized water are used in sequence for cleaning, CCl4 and acetone are mixed in a volume ratio of 1:1, and the distance between the substrate and the quartz boat containing GeSe powder is 23-25 ​​cm.

[0010] Preferably, in step D, the argon gas is injected at a flow rate of 180-200 sccm, and the temperature range of the substrate region is 360-400°C.

[0011] Beneficial effects of the present invention: The present invention provides an application of a two-dimensional GeSe material in a photodetector. The two-dimensional GeSe film is prepared by deposition on a SiO2 / Si substrate using a physical vapor deposition method. It has high crystal quality, uniform diameter, good consistency, and small compressive stress or lattice distortion. When applied to a photodetector, it can significantly improve the detection rate and sensitivity (28.28) of the photodetector, while significantly shortening the response time (14ms) and recovery time (43ms). BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 is the XRD pattern of the GeSe thin film prepared in Example 1 and Comparative Examples 1-2 of the present invention ( Figure 1 (a)) and enlarged image ( Figure 1 (b)); Figure 2 is the Raman image of the GeSe thin film prepared in Example 1 of the present invention and Comparative Examples 1-2; Figure 3 is a SEM image of the GeSe thin film prepared in Example 1 of the present invention and Comparative Examples 1-2 ( Figure 3 (a1) is the SEM image of the GeSe film prepared in Comparative Example 1. Figure 3 (b1) is the SEM image of the GeSe film prepared in Comparative Example 2. Figure 3 (c1) is the SEM image of the GeSe film prepared in Example 1) and the enlarged image ( Figure 3 (a2) is an enlarged view of the SEM image of the GeSe film prepared in Comparative Example 1. Figure 3 (b2) is an enlarged SEM image of the GeSe film prepared in Comparative Example 2. Figure 3 (c2) is an enlarged view of the SEM image of the GeSe film prepared in Example 1); Figure 4 is the IV curve of the GeSe film prepared in Example 1 of the present invention under light of different wavelengths ( Figure 4 (a)) and IT curve ( Figure 4 (b)); Figure 5 The IV curves of the GeSe thin films prepared in Example 1 and Comparative Examples 1-2 at 880nm, the IT curves at 100% power, and the IT curves at different powers of 10%, 50%, and 100% ( Figure 5(a1) is the IV curve of the GeSe film prepared in Comparative Example 1 at 880nm. Figure 5 (a2) is the IV curve of the GeSe film prepared in Comparative Example 2 at 880nm. Figure 5 (a3) is the IV curve of the GeSe film prepared in Example 1 at 880nm, and (b1) is the IT curve of the GeSe film prepared in Comparative Example 1 at 100% power. Figure 5 (b2) is the IT curve of the GeSe film prepared in Comparative Example 2 at 100% power. Figure 5 (b3) is the IT curve of the GeSe film prepared in Example 1 at 100% power, and 5 (c1) is the IT curve of the GeSe film prepared in Comparative Example 1 at different powers of 10%, 50%, and 100%. Figure 5 (c2) is the IT curve of the GeSe film prepared in comparative example 2 at different powers of 10%, 50%, and 100%. Figure 5 (c3) is the IT curve of the GeSe film prepared in Example 1 at different powers of 10%, 50% and 100%); Figure 6 The response rise time and recovery fall time of the GeSe film prepared in Example 1 and Comparative Examples 1-2 of the present invention under 880nm light source irradiation ( Figure 6 (a1) is the response rise time of the GeSe film prepared in Comparative Example 1 under 880nm light source irradiation, Figure 6 (a2) is the response rise time of the GeSe film prepared in Comparative Example 2 under 880nm light source irradiation, Figure 6 (a3) is the response rise time of the GeSe film prepared in Example 1 under 880nm light source irradiation, Figure 6 (b1) is the recovery fall time of the GeSe film prepared in Comparative Example 1 under 880nm light source irradiation, Figure 6 (b2) is the recovery fall time of the GeSe film prepared in Comparative Example 2 under 880nm light source irradiation, Figure 6 (b3) is the recovery decline time of the GeSe film prepared in Example 1 under 880nm light source irradiation). DETAILED DESCRIPTION

[0014] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] A two-dimensional GeSe film is used in a photodetector. The photodetector includes a substrate layer, an insulating layer arranged on the substrate layer, a heterostructure formed on the insulating layer, and electrodes respectively connected to the source and drain of the heterostructure, wherein the heterostructure includes at least one two-dimensional GeSe film. The two-dimensional GeSe film is deposited on a SiO2 / Si substrate by physical vapor deposition. The two-dimensional GeSe film has high crystal quality, uniform diameter, good consistency, and small compressive stress or lattice distortion. The GeSe film shows the strongest diffraction peak, and the half-width of the diffraction peak of the (111) and (400) crystal phases is relatively small, and the calculated grain size is relatively large, indicating that the GeSe film prepared on the substrate has the best crystal quality. Analysis shows that the internal stress is relatively small and the quality is the best. This is because the lattice mismatch between the SiO2 / Si substrate and the GeSe film interface is relatively small.

[0016] Example 1 A method for preparing a two-dimensional GeSe thin film comprises the following steps: A. Accurately weigh 25 mg of GeSe powder and place it evenly in a quartz boat, and then place the quartz boat in the center of the quartz tube; B. The SiO2 / Si substrate was ultrasonically cleaned for 25 min using a mixed solution of CCl4 and acetone, ethanol and deionized water in sequence, and then dried in a nitrogen atmosphere. The cleaned substrate was placed downstream of the heating zone, ensuring that the distance between the substrate and the bottom of the quartz tube was 4 cm, and the distance between the substrate and the quartz boat containing GeSe powder was 24 cm; C. Use a vacuum pump to evacuate the inside of the quartz tube to a vacuum state, and then flush the quartz tube with argon gas at a flow rate of 450 sccm for 10 minutes; D. While maintaining the argon gas flow rate of 190 sccm, heat the center of the quartz tube to 560°C at a heating rate of 20°C / min, the temperature range of the substrate area is 380°C, and then keep the temperature for reaction for 70 minutes; E. After the reaction is completed, wait for the system to cool naturally to room temperature and then take out the substrate. A layer of black GeSe film is evenly grown on the substrate.

[0017] Example 2 A method for preparing a two-dimensional GeSe thin film comprises the following steps: A. Accurately weigh 20 mg of GeSe powder and place it evenly in a quartz boat, and then place the quartz boat in the center of the quartz tube; B. The SiO2 / Si substrate was ultrasonically cleaned for 30 min using a mixed solution of CCl4 and acetone, ethanol and deionized water in sequence, and then dried in a nitrogen atmosphere. The cleaned substrate was placed downstream of the heating zone, ensuring that the distance between the substrate and the bottom of the quartz tube was 3 cm, and the distance between the substrate and the quartz boat containing GeSe powder was 25 cm; C. Use a vacuum pump to evacuate the inside of the quartz tube to a vacuum state, and then flush the quartz tube with argon gas at a flow rate of 460 sccm for 10 minutes; D. While maintaining the argon gas flow rate of 200 sccm, heat the center of the quartz tube to 550°C at a heating rate of 20°C / min, the temperature range of the substrate area is 360°C, and then keep the temperature for reaction for 80 minutes; E. After the reaction is completed, wait for the system to cool naturally to room temperature and then take out the substrate. A layer of black GeSe film is evenly grown on the substrate.

[0018] Example 3 A method for preparing a two-dimensional GeSe thin film comprises the following steps: A. Accurately weigh 30 mg of GeSe powder and place it evenly in a quartz boat, and then place the quartz boat in the center of the quartz tube; B. The SiO2 / Si substrate was ultrasonically cleaned for 20 min using a mixed solution of CCl4 and acetone, ethanol and deionized water in sequence, and then dried in a nitrogen atmosphere. The cleaned substrate was placed downstream of the heating zone, ensuring that the distance between the substrate and the bottom of the quartz tube was 5 cm, and the distance between the substrate and the quartz boat containing GeSe powder was 23 cm; C. Use a vacuum pump to evacuate the inside of the quartz tube to a vacuum state, and then flush the quartz tube with argon gas at a flow rate of 440 sccm for 10 minutes; D. While maintaining the argon gas flow rate of 180 sccm, heat the center of the quartz tube to 570°C at a heating rate of 20°C / min, the temperature range of the substrate area is 400°C, and then keep the temperature for reaction for 60 minutes; E. After the reaction is completed, wait for the system to cool naturally to room temperature and then take out the substrate. A layer of black GeSe film is evenly grown on the substrate.

[0019] Comparative Example 1 A method for preparing a two-dimensional GeSe thin film comprises the following steps: A. Accurately weigh 25 mg of GeSe powder and place it evenly in a quartz boat, and then place the quartz boat in the center of the quartz tube; B. The ceramic substrate was ultrasonically cleaned for 25 min using a mixed solution of CCl4 and acetone, ethanol and deionized water, and then dried in a nitrogen atmosphere. The cleaned substrate was placed downstream of the heating zone, ensuring that the distance between the substrate and the bottom of the quartz tube was 4 cm, and the distance between the substrate and the quartz boat containing GeSe powder was 24 cm; C. Use a vacuum pump to evacuate the inside of the quartz tube to a vacuum state, and then flush the quartz tube with argon gas at a flow rate of 450 sccm for 10 minutes; D. While maintaining the argon gas flow rate of 190 sccm, heat the center of the quartz tube to 560°C at a heating rate of 20°C / min, the temperature range of the substrate area is 380°C, and then keep the temperature for reaction for 70 minutes; E. After the reaction is completed, wait for the system to cool naturally to room temperature and then take out the substrate. A layer of black GeSe film is evenly grown on the substrate.

[0020] Comparative Example 2 A method for preparing a two-dimensional GeSe thin film comprises the following steps: A. Accurately weigh 25 mg of GeSe powder and place it evenly in a quartz boat, and then place the quartz boat in the center of the quartz tube; B. The glass slide substrate was ultrasonically cleaned for 25 min using a mixed solution of CCl4 and acetone, ethanol and deionized water, and then dried in a nitrogen atmosphere. The cleaned substrate was placed downstream of the heating zone, ensuring that the distance between the substrate and the bottom of the quartz tube was 4 cm, and the distance between the substrate and the quartz boat containing GeSe powder was 24 cm; C. Use a vacuum pump to evacuate the inside of the quartz tube to a vacuum state, and then flush the quartz tube with argon gas at a flow rate of 450 sccm for 10 minutes; D. While maintaining the argon gas flow rate of 190 sccm, heat the center of the quartz tube to 560°C at a heating rate of 20°C / min, the temperature range of the substrate area is 380°C, and then keep the temperature for reaction for 70 minutes; E. After the reaction is completed, wait for the system to cool naturally to room temperature and then take out the substrate. A layer of black GeSe film is evenly grown on the substrate.

[0021] Performance Testing (1) Structural characterization The GeSe thin films prepared in Example 1, Comparative Example 1 and Comparative Example 2 were characterized using XRD, SEM and other techniques. XRD generates diffraction peaks through the interaction between X-rays and crystals to analyze the crystal structure, phase composition and lattice parameters. SEM observes the surface morphology and microstructure of the samples.

[0022] X-ray diffraction (XRD) patterns of GeSe films grown on different substrates are shown in Figure 2. Figure 1(a). The characteristic peaks of the orthorhombic GeSe structure (JCPDS NO.48-1226) crystal plane diffraction are marked with black dots. The asterisks correspond to the characteristic peaks of the ceramic sheet (Al2O3). The two significant peaks at 32.18° and 33.24° correspond to the GeSe (111) and (400) crystal plane diffraction peaks, respectively. No impurity peaks were detected in the diffraction pattern, indicating that it is composed of pure GeSe. The XRD pattern shows that different substrates have a significant effect on the crystal structure and quality of GeSe films, which may be related to factors such as the lattice matching degree, surface energy, and thermal expansion coefficient of the substrate.

[0023] The Debye-Scherrer formula can be used to calculate the grain sizes (d(111)) and (d(400)) corresponding to the (111) and (400) diffraction peaks of GeSe films: .

[0024] Where, is the half-width at half maximum (FWHM) of the diffraction peak, is the Bragg diffraction angle of GeSe, is the Cu diffraction wavelength of XRD (1.54046Å), and the grain sizes corresponding to the (111) and (400) diffraction peaks of GeSe films grown on different substrates are shown in Table 1.

[0025] Table 1 Lattice parameters of GeSe films grown on different substrates

[0026] from Figure 1 As can be seen from (a) and Table 1, the GeSe film on SiO2 / Si substrate shows the strongest diffraction peak, and the half-height width of the diffraction peak of the (111) and (400) crystal phases is relatively small, and the calculated grain size is relatively large, indicating that the crystal quality of the GeSe film prepared on this substrate is the best. In addition, the (111) diffraction peak of the prepared GeSe film is relatively strong, indicating that it is preferentially oriented along the (111) crystal plane. The (111) diffraction peak intensity of the GeSe film grown on the ceramic substrate is second, the grain size is small, and the crystal quality is acceptable; while the (111) diffraction peak of the GeSe film grown on the glass slide substrate is the weakest, and the grain size is relatively small, indicating that the crystal quality is low. In general, SiO2 / Si substrate is the best substrate choice for growing high-quality GeSe films. Figure 1 Figure (b) shows the enlarged view of the GeSe (111) and (400) diffraction peaks. It can be clearly seen that the (111) and (400) diffraction peaks of the GeSe film grown on the glass slide are both shifted to a low angle by 0.03°, which is due to the distortion or stress in the lattice of the GeSe film grown on the glass slide.

[0027] The strain corresponding to the (111) and (400) crystal planes of GeSe thin films is calculated using the lattice strain formula ( (111)) and ( (400)): ε = (d - d0) / d0, where d is the actual lattice spacing of the test sample and d0 is the lattice spacing of the standard card spectrum sample. For thin film materials, when d < d0, it indicates compressive stress (ε < 0); when d > d0, it indicates tensile stress (ε > 0). Taking standard GeSe as an example, the lattice plane spacing d(111) of its (111) crystal plane is 2.7900, and the lattice plane spacing d(400) of its (400) crystal plane is 2.7100. By measuring the lattice plane spacings d(111) and d(400) corresponding to the (111) and (400) diffraction peaks of the GeSe thin films grown on different substrates, the corresponding strains can be calculated respectively (111), (400), and the specific data are shown in Table 2.

[0028] Table 2 Lattice strain data of GeSe thin films grown on different substrates

[0029] As can be seen from Table 2, | (111)| 对比例2 > | (111)| 对比例1 > | (111)| 实施例1 , and | (400)| 对比例2 > | (400)| 对比例1 > | (400)| 实施例1 . Using X-ray diffraction (XRD) data to calculate stress usually involves changes in lattice spacing. The existence of stress will cause lattice distortion, which in turn causes the shift of diffraction peaks. By analyzing the data in the table, we can observe the d < d0 value, which indicates that there is compressive stress between the lattices of the GeSe thin film.

[0030] Combined with Figure 1 (b) and the data in Table 2, it can be seen that the XRD diffraction peak positions of the GeSe thin films prepared on the SiO2 / Si substrate basically do not change, and the strains corresponding to the (111) and (400) crystal planes ( (111)) and ( The value of (400)) is relatively small, indicating that the internal stress of the GeSe film prepared on the SiO2 / Si substrate in Example 1 is relatively small and the quality is the best. This is because the lattice mismatch between the SiO2 / Si substrate and the GeSe film interface is relatively small. There is good lattice matching between the SiO2 / Si substrate and GeSe, and the SiO2 / Si substrate is a single crystal substrate, which promotes the growth of the GeSe film along a specific (111) crystal plane to form an ordered crystal structure. The diffraction peak position of the GeSe film grown on the ceramic substrate has basically not changed, and the strain corresponding to the (111) and (400) crystal planes ( (111)) and ( The value of (400) is relatively small, indicating that the internal stress of the GeSe film prepared on the ceramic substrate is small and the quality is good, because the lattice mismatch between the ceramic substrate and the GeSe film interface is small. However, the diffraction peak position of the GeSe film grown on the glass substrate has a large shift, and the strain corresponding to the (111) and (400) crystal planes ( (111)) and ( (400)) has the largest value, which indicates that the internal stress of the GeSe film prepared on the glass slide substrate is relatively the largest and the quality is the worst. This phenomenon may be due to the large lattice mismatch between the glass slide substrate and the GeSe film interface, which leads to significant distortion of the lattice at the interface.

[0031] Figure 2 The Raman spectra of GeSe films grown on different substrates are shown. According to the symmetry principle of the D2h16 group, GeSe theoretically has 12 Raman active vibration modes, including 4 Ag modes, 2 B modes, and 4 C modes. 1g Mode, 4 B 2g Mode and 2 B 3g mode. Figure 3 In the Raman spectrum of -1 A g3 Mode, 150 cm -1 B 3g mode, and 188 cm -1 A g1pattern. These findings are highly consistent with previous reports on the position of the GeSe Raman peak, confirming the structure and composition of the GeSe films we prepared. In addition, different substrates have a significant effect on the position and intensity of the peak. The Raman peak intensity on the ceramic wafer and SiO2 / Si substrate is higher, indicating that the film crystal quality is better, and the peak position is consistent with the standard GeSe data; while the Raman signal on the glass slide substrate is weaker, indicating that the film quality is slightly inferior, and there may be lattice defects or insufficient thickness. In addition, the slight shift of the Raman peak caused by different substrates may be related to lattice stress or the interface interaction between the substrate and the film. This shows that ceramic wafers and SiO2 / Si substrates are better substrate choices for growing high-quality GeSe films.

[0032] Figure 3 Scanning electron microscope (SEM) images of GeSe films prepared on different substrates are revealed. It can be clearly seen that the GeSe film grown on the ceramic wafer forms a vertical array of nanowires, which are closely arranged and the diameter of the nanowires is relatively consistent. In contrast, although the GeSe film grown on the glass slide is also vertically distributed, it does not form a nanowire array, but presents a polyhedral morphology. Compared with those grown on ceramic wafers, the GeSe nanowires grown on SiO2 / Si substrates appear longer, thinner and more densely arranged.

[0033] (2) Photoelectric performance test A high-performance FS380Pro semiconductor parameter test system was used to measure the optoelectronic properties of GeSe thin films under different substrates. The light source is provided by a 4-channel LED light source MLED4, which can achieve high energy output of ultraviolet, visible, infrared light, etc., which are 365 nm, 530 nm, 660 nm, and 880 nm respectively. The GeSe thin films prepared by irradiation Example 1, Comparative Example 1 and Comparative Example 2 were tested and analyzed in detail.

[0034] The results were Figure 4 (a) IV curve and Figure 4(b) is presented in the form of an IT curve. The experimental results show that there is a good linear relationship between current (I) and voltage (V), which indicates that the contact between the Ag metal and the GeSe semiconductor in the device is an ohmic contact. In addition, the photocurrent generated by the constructed GeSe photodetector under different light sources is greater than its dark current, which shows that the detector can respond under different light sources. However, with the increase of the wavelength of the light source, the photocurrent response of the GeSe photodetector gradually increases. In particular, under the irradiation of a light source with a wavelength of 880 nm, the photocurrent response of the GeSe photodetector is most significant. These results reveal the performance changes of GeSe photodetectors under different wavelengths of light, and provide an important basis for further optimization and application. In order to explore the photoresponse characteristics of GeSe photodetectors prepared on different substrates under 880nm wavelength light, we conducted photoelectric performance tests, and its IV curve and IT curve are shown in the following figure. Figure 5 As shown. Figure 5 As can be seen from (a1-a3), the dark current, photocurrent and voltage of the prepared GeSe photodetector device show a linear relationship and exhibit good ohmic characteristics. Under the illumination condition of 880nm wavelength, the photocurrent of the prepared GeSe photodetector increases with the increase of voltage, showing obvious photoelectric response characteristics. Figure 5 (b1-b3) and (c1-c3) show the current-time (IT) response characteristics of GeSe photodetectors prepared on different substrates during the light switching cycle under a bias voltage of 5 V. It can be clearly observed from these figures that the photocurrent shows obvious periodic changes during the light source on-off cycle, which indicates that the prepared GeSe photodetector has a fast and repeatable response to the optical signal.

[0035] By analyzing Figure 5 , we can observe that under the conditions of +5V bias voltage and 880nm wavelength illumination, the GeSe thin films grown on ceramic wafers, glass slides and SiO2 / Si substrates show the following values ​​of photocurrent Ip and dark current Id: the photocurrent of the film on the ceramic wafer is 202nA, the dark current is 7.89nA, and the photoelectric sensitivity (S) is 25.6; the photocurrent of the film on the glass slide is 8581nA, the dark current is 2239nA, and the photoelectric sensitivity (S) is 3.83; the photocurrent of the film on SiO2 / Si is 2387nA, the dark current is 84.4nA, and the photoelectric sensitivity (S) is 28.28. It can be seen that the GeSe photodetectors prepared on ceramic wafers and SiO2 / Si respectively show sensitivities as high as 25.60 and 28.28. These values ​​significantly exceed the parameters reported in the literature, thus highlighting the excellent performance of the prepared GeSe photodetectors in terms of photoelectric conversion efficiency.

[0036] Combined with the SEM images, the dark current of GeSe nanowires grown on ceramic wafers and SiO2 / Si is much smaller than that of GeSe nanoparticles grown on glass slides. This is because the conductive paths between GeSe nanowires and GeSe nanoparticles are different, such as Figure 5 As shown. Compared with the conductive path of GeSe nanoparticles, the conductive path of GeSe nanowires is very long, resulting in a very small dark current. The photoelectric sensitivity of GeSe nanoparticles grown on a glass slide is also much smaller than that of GeSe nanowires grown on ceramic sheets and SiO2 / Si. This is because the GeSe nanoparticles grown on a glass slide have a smaller light absorption area, produce fewer photogenerated electron-hole pairs, and have large lattice distortion and stress between the nanoparticles, causing photogenerated carriers to be easily captured, thus making their photoelectric sensitivity smaller. GeSe nanowires grown on ceramic sheets have a larger specific surface area, which increases their light absorption area, produces relatively more photogenerated electron-hole pairs, and has smaller lattice distortion and stress between the nanowires, causing photogenerated carriers to be easily transferred to between electrodes, thus making their photoelectric sensitivity relatively large. The arrangement density of GeSe nanowires grown on SiO2 / Si is greater than that of GeSe nanowires grown on ceramic sheets, making their specific surface area relatively larger. Therefore, the area for absorbing light is relatively increased, and the number of photogenerated electron-hole pairs generated is relatively increased. In addition, the lattice distortion and stress between the nanowires are relatively minimal, making it easier for photogenerated carriers to be transferred between electrodes, thus making their photoelectric sensitivity relatively maximized.

[0037] Photoelectric sensitivity (S), photoresponsivity (R), and detection rate ( ) and EQ are important parameters of the device, and the calculation formula is as follows: ， , , Where, q = e = 1.6 × 10 -19 C, C = 3 × 10 8 m / s, λ=880nm, P0=50mW / cm 2 , A=0.01cm 2 , h = 6.625 × 10 -34 JS, it was calculated that the photoresponsivity (R) of GeSe films grown on ceramic wafers, glass slides, and SiO2 / Si substrates were 0.39 mA / W, 12.68 mA / W, and 4.61 mA / W, respectively. The response time and recovery time were 16 ms and 55 ms, 34 ms and 128 ms, and 14 ms and 43 ms, respectively. The quantum efficiency and detection rate were 0.06% and 7.76×108 , 1.79% and 1.49×10 9 , 0.65% and 2.80×10 9 As can be seen from the table, the GeSe photodetector prepared on the glass slide exhibits a high responsivity, quantum efficiency and detection rate, but the very large dark current not only increases the power consumption of the device, but also reduces the working efficiency of the device and the accuracy of signal detection, which has a direct and negative impact on the performance of the optoelectronic device, further limiting its application potential in the field of photoelectric detection.

[0038] Figure 6 (a1-a3) and (b1-b3) show the photoresponse characteristics of GeSe photodetectors fabricated on ceramic wafers, glass slides, and SiO2 / Si substrates under 880nm wavelength illumination. Specifically, the rise time (τr) of the photoresponse is defined as the time required for the photocurrent to increase from 10% to 90%, while the fall time (τf) is defined as the time required for the photocurrent to decrease from 90% to 10%. According to the data provided, the photoresponse rise time and fall time of these GeSe photodetectors are as follows: the rise time of the GeSe photodetector fabricated on the ceramic wafer is 16ms and the fall time is 55ms; the rise time of the GeSe photodetector fabricated on the glass slide is 34ms and the fall time is 128ms; the rise time of the GeSe photodetector fabricated on the SiO2 / Si substrate is 14 and the fall time is 43ms. These response times and recovery times are significantly better than those reported in the literature. This shows that the prepared GeSe photodetector has a faster response speed and a shorter recovery time, which is crucial to improving the performance of photodetectors, especially in applications that require fast response, such as high-speed optical communications and real-time imaging. The parameters of GeSe photodetectors prepared on different substrates are shown in Table 3.

[0039] Table 3 Parameters of GeSe photodetectors prepared on different substrates

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. Application of two-dimensional GeSe thin film in photodetector, characterized in that: The photodetector comprises a substrate layer, an insulating layer arranged on the substrate layer, a heterostructure formed on the insulating layer, and electrodes respectively connected to the source and drain of the heterostructure, wherein the heterostructure comprises at least one two-dimensional GeSe film, the two-dimensional GeSe film is deposited on a SiO2 / Si substrate by physical vapor deposition, a slender and dense GeSe nanowire array is formed on the surface of the two-dimensional GeSe film, and the photoelectric sensitivity of the GeSe film at a wavelength of 880nm is 28.28, the response time is 14ms, and the recovery time is 43ms; The method for preparing the two-dimensional GeSe thin film comprises the following steps: A. Accurately weigh the GeSe powder and place it evenly in a quartz boat, and then place the quartz boat in the center of the quartz tube; B. The SiO2 / Si substrate was ultrasonically cleaned for 20-30 minutes and then dried in a nitrogen atmosphere. The cleaned substrate was placed downstream of the heating zone to ensure that the distance between the substrate and the bottom of the quartz tube was 3-5 cm. C. Use a vacuum pump to evacuate the inside of the quartz tube to a vacuum state, and then flush the quartz tube with argon gas at a flow rate of 440-460 sccm for 10 minutes; D. While maintaining the argon injection, heat the center of the quartz tube to 550~570℃ at a heating rate of 20℃ / min, and then keep the temperature for reaction for 60~80min; E. After the reaction is completed, wait for the system to cool naturally to room temperature and then take out the substrate. A layer of black GeSe film is evenly grown on the substrate.

2. The use of the two-dimensional GeSe thin film in a photodetector according to claim 1, characterized in that: The particle size of the GeSe powder in step A is 160 mesh, the purity is 99.99%, and the mass is 20-30 mg.

3. The use of the two-dimensional GeSe thin film in a photodetector according to claim 1, characterized in that: In the step B, a mixed solution of CCl4 and acetone, ethanol and deionized water are used for cleaning in sequence. CCl4 and acetone are mixed in a volume ratio of 1:1, and the distance between the substrate and the quartz boat containing GeSe powder is 23-25 ​​cm.

4. The use of the two-dimensional GeSe thin film in a photodetector according to claim 1, characterized in that: In the step D, the argon gas is injected at a flow rate of 180-200 sccm, and the temperature range of the substrate area is 360-400°C.

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