阅读说明：本技术 一种pvd技术生长大尺度iv-vi族化合物单晶薄膜材料的方法 (Method for growing large-scale IV-VI group compound single crystal thin film material by PVD (physical vapor deposition) technology ) 是由 王春香 赵洪泉 石轩 张国欣 张炜 于 2021-09-03 设计创作，主要内容包括：本发明公开了一种PVD技术生长大尺度IV-VI族化合物单晶薄膜材料的方法,具体包括三个主要阶段：第一阶段是准备材料,优化选择多晶粉源的重量；第二阶段将粉源和衬底放入石英管中,设置好粉源和衬底分别在石英管中的位置；第三阶段利用物理气相沉积技术生长单晶薄膜,通过优化粉源的升温速率、保温温度和时间,衬底温度,气流速度,制备出大尺度和具有规则条带形状的层状薄膜材料,为大尺度IV-VI族单晶薄膜的实验制备及其应用奠定了重要的技术基础。(The invention discloses a method for growing a large-scale IV-VI compound monocrystal thin film material by a PVD (physical vapor deposition) technology, which specifically comprises three main stages: the first stage is to prepare materials and optimally select the weight of the polycrystalline powder source; in the second stage, the powder source and the substrate are placed in a quartz tube, and the positions of the powder source and the substrate in the quartz tube are set; in the third stage, a single crystal film is grown by utilizing a physical vapor deposition technology, and a large-scale and regular strip-shaped layered film material is prepared by optimizing the heating rate, the heat preservation temperature and time of a powder source, the substrate temperature and the air flow rate, so that an important technical basis is laid for the experimental preparation and the application of a large-scale IV-VI family single crystal film.)

1. A method for growing large-scale IV-VI compound monocrystal thin film material by using PVD technology is characterized by comprising the following steps:

(1) cleaning a substrate to remove impurities, then carrying out ultrasonic treatment, and drying for later use; weighing high-purity IV-VI compound polycrystalline powder, and uniformly spreading the high-purity IV-VI compound polycrystalline powder into a quartz boat for later use;

(2) a gas flow controller, a heat insulation area I, a heating area and a heat insulation area II are sequentially arranged in a quartz tube cavity of the single-temperature-area tube furnace along the airflow direction, the heating temperature of the central position of the heating area is measured, the difference value between the measured temperature of the heating area and the measured temperature of a thermocouple is calculated, and the heating temperature is calibrated according to the difference value;

(3) placing the substrate processed in the step (1) in a heat insulation area II, placing the quartz boat after loading in the central position of the heating area, and then vacuumizing the quartz tube cavity;

(4) and (4) continuously introducing argon into the quartz tube cavity after vacuumizing in the step (3), simultaneously heating the heating area to 550 ℃, keeping the temperature for 2min, closing the heating to naturally cool the substrate to room temperature, cutting off an argon gas source, and taking out a sample to obtain the single crystal thin film material.

2. The method for growing the large-scale IV-VI compound monocrystal thin film material by the PVD (physical vapor deposition) technology as claimed in claim 1, wherein the substrate in the step (1) is a surface-polished monocrystal silicon wafer or a surface-polished oxidized monocrystal silicon wafer; the ultrasonic treatment is to sequentially add the mixture into acetone, alcohol and deionized water for ultrasonic treatment for 10 min; the drying is blowing dry with nitrogen.

3. The method for growing large-scale group IV-VI compound single crystal thin film material by PVD technique as claimed in claim 1, wherein the high-purity group IV-VI compound polycrystalline powder in step (1) is one of SnS, SnSe, GeS, GeSe, the purity is 99.999%, the ratio of the weight of the high-purity group IV-VI compound polycrystalline powder to the surface area of the substrate is (1-5) mg: 2cm²The ratio of the diameter of the quartz tube to the surface area of the sinking bottom is 1 inch: 2cm²。

4. A method for growing large-scale IV-VI compound single crystal thin film material by PVD technique as claimed in claim 1, wherein the distance between the substrate and the central position of the heating zone in step (3) is 15 cm.

5. A method for growing large-scale IV-VI compound monocrystal thin film material by PVD technique as claimed in claim 1, wherein the vacuum degree in step (3) is 1-3 Pa.

6. The method for growing large-scale group IV-VI compound single crystal thin film material by PVD technique as claimed in claim 1, wherein the argon gas flow rate in step (4) is 100 sccm.

7. The method for growing the large-scale IV-VI compound single crystal thin film material by the PVD technique as claimed in claim 1, wherein the heating zone temperature rise process in the step (4) is as follows:

firstly, heating to 200 ℃ for 20 min;

then the temperature is increased to 550 ℃ for 10 min.

8. A method for growing a large-scale IV-VI compound single crystal thin film material by using the PVD technique as claimed in any claim 1 to 7, further comprising: scrubbing the quartz tube chamber and the quartz boat by dilute hydrochloric acid, then scrubbing by alcohol, finally cleaning by deionized water, and drying for reuse.

Technical Field

The invention relates to the technical field of new materials, in particular to a method for growing a large-scale IV-VI compound monocrystal thin film material by using a PVD (physical vapor deposition) technology.

Background

The graphene is formed by carbon atoms passing through SP²Three carbon atoms hybridized and close to the carbon atoms form a sigma bond of 120 degrees to form a honeycomb structure. The simple structure of graphene has many unique physical phenomena including dirac fermi, fractional and room temperature quantum hall effects, minimum quantum conduction, etc. Graphene has many good properties, such as the lightest carrier mass, the highest current density, the longest mean free path at room temperature, the highest carrier mobility, etc., wherein an ultra-high carrier mobility offers the potential for developing fast electronic devices. However, the ultra-high mobility of graphene is caused by zero band gap, and the lack of an intrinsic forbidden band width results in a low on/off current ratio of the graphene transistor, thereby limiting the wide application of the graphene transistor. Therefore, there is a need to develop other two-dimensional materials with wide tunable bandgaps to achieve multifunctional nanoscale optoelectronic devices.

Layered group IV-VI compounds are a new class of semiconductor materials, including SnS, SnSe, GeS, GeSe, and the like. The development and application of semiconductor materials and technologies in the field of photoelectric detection urgently need a novel semiconductor material which can meet the requirements of detection from visible-infrared bands, has high-speed photoresponse characteristics, requires excellent chemical stability and the like, and can better meet the requirements of GeSe in IV-VI compound two-dimensional materials. In the two-dimensional materials of IV-VI compounds, the GeSe single crystal film has a direct band gap energy band structure and a distorted NaCl lattice structure. The IV-VI compound represented by GeSe has a very complex energy band structure, and the material has a crystal structure similar to graphene, belongs to a layered material, has a complex energy band structure, and has a light absorption spectrum range almost coincident with the whole solar light wave band, so the material has a great application prospect in the aspects of near infrared photodetectors and electron tunneling devices. The GeSe single crystal thin film material has extremely low carrier effective substanceAmount, effective carrier mass of GeSe monolayer less than 0.1m₀And the carrier mass in the monoatomic layer is also adjustable in strain, and the adjustable range is 0.03-0.61m₀It is predicted that such materials will have extremely high carrier mobility. In addition, the GeSe single crystal also has high surface oxidation resistance and surface inertness, and dangling bonds are extremely difficult to generate on the surface, which also means that the material has excellent stability and high photoelectric response rate. The GeSe single crystal film has extremely high application value in the aspects of micro-mechanics, electric heating, optoelectronics and the like due to the properties. The calculation of Density Functional Theory (DFT) shows that the structure of single-layer GeSe has four structures of beta-GeSe, gamma-GeSe, delta-GeSe and beta 0-GeSe besides the most common layered alpha-GeSe. The binding energy and the energy band structure of five germanium selenide isomorphs are respectively 3.88eV, 3.85eV, 3.83eV, 3.87eV and 3.78eV of the binding energy of beta 2-GeSe, beta 1-GeSe, gamma-GeSe, delta-GeSe and epsilon-GeSe, which are semiconductor properties. The five polymorphic structures of GeSe exhibit various types of energy band structures, which have very important roles in photoelectrons and photons. The alpha-GeSe, the gamma-GeSe, the delta-GeSe and the epsilon-GeSe are anisotropic structures, the beta-GeSe is an isotropic structure, the alpha-GeSe is the form which can form the highest energy in the five crystal forms, and the orthogonal structure of the alpha-GeSe is the most stable in the air.

The indirect band gap of the bulk alpha-GeSe is about 1.08eV, and the direct band gap of the monolayer alpha-GeSe calculated by the DFT method is about 1.7 eV. The hole mobility of the single crystal alpha-GeSe is 95cm at 300K²V^-1s^-1663cm at 112K²V^-1s^-1. The DFT theory predicts that the average hole mobility of the single-layer alpha-GeSe at 300K is as high as 1100cm²V^-1s^-1. GeSe has a very high photo response along the a3 direction (perpendicular to the plane). In 2013, Mukherjee et al synthesized high-quality micron-sized GeSe single crystal nanosheets by physical vapor transport and deposition technology, and studied the kinetic principle in the growth process. But the sample size is only a few microns and the thickness is above 100 nanometers. In 2016, Xue et al prepared high quality polypeptides using Rapid Thermal Sublimation (RTS)The crystalline GeSe thin film and the solar cell prepared by the process have the energy conversion efficiency of 1.48 percent and good stability, and prove the great potential of the GeSe thin film in the aspect of photovoltaic application. Yap et al in 2017 obtained a 10-micron GeSe nanosheet by a mechanical stripping method, studied anisotropy of electron transport, conductivity and effective mass, and theoretically proved by a Density Functional Theory (DFT). GeSe-MoS is prepared by utilizing P type doping of GeSe and N type doping of molybdenum disulfide₂The heterojunction provides a new idea for preparing the heterojunction by combining GeSe and N-type transition metal sulfide. In 2019, an ultra-thin long and thin hexagonal GeSe nanosheet is successfully synthesized by the Liu team by a rapid cooling physical vapor deposition method, the anisotropy of the nanosheet is researched, a field effect transistor based on the long and thin hexagonal GeSe nanosheet is manufactured, and the p-type semiconductor property with high photoresponse is shown. These works have conducted some degree of theoretical and experimental research on micron-sized, platelet-shaped GeSe crystals. However, experimental preparation of large-scale GeSe single crystal thin films is not yet realized, so experimental exploration on aspects of anisotropic current transport, material heterojunction and array monolithic integration of the material is limited, and further application of the material is restricted.

Therefore, how to provide a new large-scale group IV-VI compound single crystal thin film material is a problem to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the invention provides a method for growing a large-scale IV-VI group compound single crystal film on a silicon wafer substrate based on a PVD technology, and the grown large-scale semiconductor single crystal film material can be applied to the fields of semiconductor electronics, photoelectric devices, thermoelectric devices and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for growing large-scale IV-VI compound monocrystal thin film material by PVD technique includes the following steps:

(1) cleaning a substrate to remove impurities, then carrying out ultrasonic treatment, and drying for later use; weighing high-purity IV-VI compound polycrystalline powder, and uniformly spreading the high-purity IV-VI compound polycrystalline powder into a quartz boat for later use;

(2) a gas flow controller, a heat insulation area I, a heating area and a heat insulation area II are sequentially arranged in a quartz tube cavity of the single-temperature-area tube furnace along the airflow direction, the heating temperature of the central position of the heating area is measured, the difference value between the measured temperature of the heating area and the measured temperature of a thermocouple is calculated, and the heating temperature is calibrated according to the difference value;

(3) placing the substrate processed in the step (1) in a heat insulation area II, placing the quartz boat after loading in the central position of the heating area, and then vacuumizing the quartz tube cavity;

(4) and (4) continuously introducing argon into the quartz tube cavity after vacuumizing in the step (3), simultaneously heating the heating area to 550 ℃, keeping the temperature for 2min, closing the heating to naturally cool the substrate to room temperature, cutting off an argon gas source, and taking out a sample to obtain the single crystal thin film material.

Preferably, the substrate in the step (1) is a surface-polished monocrystalline silicon wafer or a surface-polished oxidized monocrystalline silicon wafer; the ultrasonic treatment is to sequentially add the mixture into acetone, alcohol and deionized water for ultrasonic treatment for 10 min; the drying is blowing dry with nitrogen.

Preferably, the high-purity group IV-VI compound polycrystalline powder in step (1) is one of SnS, SnSe, GeS, and GeSe, and has a purity of 99.999%, and a ratio of the weight of the high-purity group IV-VI compound polycrystalline powder to the surface area of the substrate is (1-5) mg: 2cm²The ratio of the diameter of the quartz tube to the surface area of the sinking bottom is 1 inch: 2cm²。

The beneficial effects of the preferred technical scheme are as follows: the ratio of the group IV-VI compound polycrystalline powder determines the growth density of the single crystal thin film, and the larger the weight, the higher the growth density of the single crystal thin film, and thus it is necessary to control it within a reasonable range.

Preferably, the distance between the substrate and the central position of the heating zone in the step (3) is 15 cm.

The beneficial effects of the preferred technical scheme are as follows: the substrate temperature plays a key role in the formation of the single crystal thin film and provides proper heat energy for the nucleation growth of the single crystal thin film, thereby forming the high-quality single crystal thin film. The temperature of the substrate silicon wafer is optimized by experiment, preferably about 150 ℃. Under the condition of the substrate temperature, the grown monocrystal film has larger scale and more regular shape. When the temperature of the substrate is lower than 150 ℃, the lower the temperature is, the denser the nucleation points of the crystal are, but the finer the crystal branches are; when the temperature of the substrate is higher than 150 ℃, the higher the temperature is, the crystals tend to agglomerate and cluster, the thickness is about large, when the distance between the substrate wafer and the center of the heat source is 15cm, the temperature of the substrate is 150 ℃, the thickness of the grown monocrystal film is about 100nm, the dimension is more than hundred microns, and the agglomeration is less.

Preferably, the vacuum degree of the vacuum pumping in the step (3) is 1-3 Pa.

The beneficial effects of the preferred technical scheme are as follows: the gas molecules and impurities such as water vapor, dust and the like absorbed in the quartz tube cavity can be removed by vacuumizing.

Preferably, the flow rate of argon gas in step (4) is 100 sccm.

Preferably, the heating zone temperature raising process in the step (4) is as follows:

firstly, heating to 200 ℃ for 20 min;

then the temperature is increased to 550 ℃ for 10 min.

Preferably, the method further comprises the following steps: scrubbing the quartz tube chamber and the quartz boat by dilute hydrochloric acid, then scrubbing by alcohol, finally cleaning by deionized water, and drying for reuse.

According to the technical scheme, compared with the prior art, the invention discloses a method for growing a large-scale IV-VI compound monocrystal thin film material by using a PVD (physical vapor deposition) technology, which has the following beneficial effects:

the process for growing the thin film crystal material by the Physical Vapor Deposition (PVD) technology is simple, the material consumption is less, the film formation is uniform and compact, the binding force with a substrate is strong, and the cost is low. Based on PVD technology, the invention prepares the single crystal film with the dimension of hundreds of microns to more than hundreds of microns on the silicon substrate by optimizing experimental parameters such as the weight of the powder source, the heating rate of the powder source, the growth temperature of the powder source, the temperature of the substrate wafer, the flow rate of the carrier gas and the like, and with relatively simple equipment conditions and low experimental cost. The scale of the single crystal film prepared by the method is about more than 10 times that of the single crystal film reported previously. Therefore, the technical scheme of the invention has important practical significance on solving the basic problem of large-scale growth of IV-VI materials represented by GeSe.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of experimental equipment for PVD growth of single crystal thin film materials;

FIG. 2 is a graph showing the temperature gradient at each position in the quartz tube as the length from the heating center increases;

FIG. 3 is a schematic diagram showing the temperature and gas flow settings during the growth of an alpha-GeSe single crystal thin film material by PVD techniques;

FIG. 4 is an optical micrograph of an α -GeSe single crystal thin film material obtained in example 1;

FIG. 5 is a Raman spectrum test chart of the GeSe thin film obtained in example 1, wherein an excitation source is a 532nm continuous laser;

FIG. 6 is a fluorescence spectrum of the GeSe thin film obtained in example 1, wherein the excitation source is a 532nm continuous laser, 6a is a spectrum at room temperature, and 6b is a spectrum at a low temperature of 10K;

FIG. 7 is an I-V test chart of FET devices made of GeSe thin film material obtained in example 1.7 a is a schematic diagram of the principle of the device, 7b is an optical micrograph of the device, and 7c is I of the device_ds-V_dsCurve, 7d is the I of the device_ds-V_gCurve line.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment 1 of the invention provides a method for growing a large-scale GeSe single crystal thin film material by using a PVD (physical vapor deposition) technology, wherein the preparation is carried out in a single-heating tube type furnace, and the specific structure is shown in figure 1; the temperature gradient changes at each location as the length from the heating center increases as shown in fig. 2; the temperature and gas flow settings during the preparative growth are schematically shown in figure 3.

The method specifically comprises the following steps:

(1) the substrate selected for preparing the sample is a monocrystalline silicon wafer with polished surface or a monocrystalline silicon wafer with polished and oxidized surface; before preparing a sample, cleaning the substrate to remove surface impurities; ultrasonically cleaning the substrate in acetone, alcohol and deionized water for 10 min; then the cleaned substrate is dried by nitrogen for standby; substrate surface area 2cm²Weighing 1-5mg of high-purity GeSe (99.999%) polycrystalline powder, and uniformly spreading the powder into a quartz boat for later use;

(2) the diameter of a quartz tube chamber of the single-temperature-zone tube furnace is 1 inch, a gas flow controller, a heat insulation zone I, a heating zone and a heat insulation zone II are sequentially arranged in the quartz tube chamber along the airflow direction, a thermometer is used for measuring the heating temperature of the central position of the heating zone, the difference value between the measured temperature and the measured temperature of a thermocouple is calculated, and the heating temperature is calibrated according to the difference value;

(3) placing the substrate treated in the step (1) in a heat insulation zone II, wherein the distance between the substrate and the center of a heating zone is 15cm, then placing the quartz boat with the material loaded in the center of the heating zone, and then pumping the quartz tube cavity to the vacuum degree of 1 Pa;

(4) continuously introducing argon into the quartz tube cavity vacuumized in the step (3) at the flow rate of 100sccm, heating the heating area to 200 ℃ within 20min, heating to 550 ℃ within 10min, then preserving heat for 2min, turning off heating, sliding the heating area away from the powder source and the substrate, naturally cooling the substrate to room temperature, cutting off the argon source, and taking out a sample to obtain a single crystal thin film material;

(5) scrubbing the quartz tube chamber and the quartz boat by dilute hydrochloric acid, then scrubbing by alcohol, finally cleaning by deionized water, and drying for reuse.

Example 2

The technical scheme disclosed in the embodiment 2 of the invention is basically the same as that in the embodiment 1, and only high-purity GeSe (99.999%) polycrystalline powder is replaced by high-purity SnS (99.999%) polycrystalline powder.

Example 3

The technical scheme disclosed in embodiment 3 of the invention is basically the same as that in embodiment 1, and only high-purity GeSe (99.999%) polycrystalline powder is replaced by high-purity SnSe (99.999%) polycrystalline powder.

Example 4

The technical scheme disclosed in embodiment 4 of the present invention is substantially the same as that in embodiment 1, and only high-purity GeSe (99.999%) polycrystalline powder is replaced by high-purity GeS (99.999%) polycrystalline powder.

Effect verification

An optical micrograph of the material prepared based on the protocol of example 1 is shown in FIG. 4. The samples are regular, strip-like films, typically having dimensions above 100 μm. The regular strip shape accords with the crystal morphology of the alpha-GeSe single crystal, and shows that the prepared GeSe film is a single crystal material. In contrast, the GeSe single crystal thin film samples prepared by various GeSe single crystal thin film preparation schemes reported in the documents before generally have the dimension of 1-10 μm. Therefore, the size of the GeSe single crystal film prepared by the method is far larger than that of the GeSe single crystal film prepared by the method reported in the literature (about 10 times).

In order to verify that the strip-shaped GeSe thin film prepared in example 1 was an α -GeSe single crystal material, a series of tests were performed on the material, including mainly Raman spectrum test, fluorescence spectrum test of the thinned material, and electrical test of the device. Compared with the reported test result of the alpha-GeSe single crystal material, the test result of the material prepared by the method accords with the characteristics of the alpha-GeSe single crystal film.

1. And (3) Raman spectrum testing:

the raman spectrum is a vibrational spectrum of molecules. Raman spectroscopy can provide information about the substance itself, e.g. moleculesThe energy level of vibration and the like, and the position of the Raman peak corresponds to the chemical composition, the phase state, the crystal form and the like of a substance. FIG. 5 is a Raman spectrum test chart of the GeSe thin film prepared in example 1. The test was carried out with a laser power of 50. mu.W, 250. mu.W and 500. mu.W, respectively, using 532nm continuous laser as excitation source. At 81cm^-1、151cm^-1、175cm^-1And 188cm^-1Three distinct raman characteristic peaks can be observed, which correspond to the a of the germanium-selenium bond respectively¹g、B¹²g、B²²g and A³And g phonon vibration modes, wherein the vibration modes conform to the characteristic vibration mode of the alpha-GeSe single crystal film, and the prepared GeSe sample and the alpha-GeSe single crystal material have consistent phase composition and structure.

2. Fluorescence spectrum test:

the fluorescence spectrum is a spectrogram of intensity or energy distribution of light with different wavelengths formed by light emission through recombination of electrons and holes in a quasi-equilibrium state after electrons transit from a valence band to a conduction band and holes are left in the valence band under the excitation of laser, and the electrons and the holes in the quasi-equilibrium state reach the respective unoccupied lowest excited states through relaxation in the respective conduction band and the valence band to form the quasi-equilibrium state, and is generally used for semiconductor detection and characterization. The forbidden bandwidth of the direct band gap semiconductor material can be determined through the PL peak position. Firstly, thinning the prepared GeSe single crystal film by using a heat treatment thinning method, and then testing the fluorescence spectrum of the thinned material by using 532nm continuous laser as an excitation source, wherein the test result is shown in figure 6. FIG. 6a shows the fluorescence spectrum at room temperature, and FIG. 6b shows the fluorescence spectrum at low temperature of 10K. At normal temperature, three fluorescence characteristic spectrum peaks of the GeSe single crystal film are respectively found, namely 591nm, 659nm and 738 nm; at the low temperature of 10K, the positions of three fluorescence characteristic spectrum peaks are 590nm, 655nm and 735nm respectively. At the low temperature of 10K, the positions of three fluorescence spectrum peaks have red shifts of 1-4 nanometers compared with the positions at the normal temperature, and meanwhile, the intensity of the fluorescence spectrum peaks is improved by about 70 percent. The red shift of the fluorescence spectrum peak is caused by that the band gap width of the energy band of the GeSe single crystal material is slightly shrunk at low temperature; the spectral peak intensity is improved due to the improved quantum efficiency of the material at low temperatures. The test results are in accordance with the basic characteristics of the low temperature spectrum. The test result is simultaneously consistent with the fluorescence characteristic spectrum of the alpha-GeSe single crystal two-dimensional material reported in the literature.

3. I-V curve testing of GeSe Field Effect Transistors (FETs). After the prepared GeSe single crystal thin film was prepared into an FET device, we tested the I-V curve of the device using a Keithley4200 electrical tester. Fig. 7a and 7b are a schematic diagram of the device and an optical micrograph. FIG. 7c shows source-drain current-source-drain voltage (I) of the device at different back gate voltages_ds-V_ds) Graph is shown. When the grid voltage Vg is less than 0, the source-drain current I_dsOnly at source-drain voltage V_dsWhen > 0, it follows V_dsIs increased rapidly, and when V is increased_dsWhen < 0, I_dsWith V_dsWith little change, the conductive carriers in the channel are dominated by holes. When the grid voltage Vg is more than 0, the source-drain current I_dsOnly at source-drain voltage V_dsIf < 0, it follows V_dsIs increased rapidly, and when V is increased_dsWhen > 0, I_dsWith V_dsWith little change, the conductive carriers in the channel are dominated by electrons. This indicates that the prepared GeSe material is a typical bipolar conductive material. FIG. 7d shows the source-drain current-gate voltage (I) of the device at different source-drain voltages_ds-V_g) Graph is shown. I is_dsWith V_gIs typically p-type semiconductor material characteristic I_ds-V_gCurve line. The test results of fig. 7 show that the FET devices prepared from the GeSe thin films grown in this work exhibit significant bipolar conductivity characteristics and p-type semiconductor material characteristics, consistent with the material conductivity characteristics of α -GeSe single crystal thin films reported in the literature.

In conclusion, the test analysis of the work shows that the alpha-GeSe single crystal thin film material with the scale of hundreds of micrometers to hundreds of micrometers is successfully prepared by optimizing growth parameters based on the PVD technology. The material dimension is far larger than the growth preparation dimension of the alpha-GeSe single crystal thin film material reported in the literature. Therefore, the present work contributes to push the research on α -GeSe single crystal thin films to a new height.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.