A method for preparing a large-area two-dimensional indium selenide film crystal material based on a rapid cooling chemical vapor deposition method, a product prepared by the method and an application thereof

Abstract

The application discloses a method for preparing a large-area two-dimensional indium selenide film crystal material based on a rapid cooling chemical vapor deposition method, and a product and application thereof, and relates to the technical field of two-dimensional material preparation. In the method, the vertical distance between a precursor and a substrate is about 3 millimeters or about 1 millimeter, and compared with a distance of more than 10 cm required by a traditional chemical vapor deposition method, the super-short transmission distance can provide a stable, uniform and continuous gas source supply on a growth substrate, so that a large-size indium selenide film is obtained. The two-dimensional indium selenide film prepared by the method has high electron mobility, high quality and a relatively wide band gap, and the beta prime and alpha phases have ferroelectric effects, so that the two-dimensional indium selenide film has a wide prospect in applications of ferroelectric transistors and photoelectric detectors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of two-dimensional material preparation, and particularly relates to a method for preparing large-area two-dimensional indium selenide film crystal material based on a rapid cooling chemical vapor deposition method, a product prepared by the method and application. BACKGROUND

[0002] Among a large number of two-dimensional materials, indium selenide (In2Se3) of III-VI semiconductor with a layered structure is a rising star. In2Se3 has five main crystal phases, i.e., alpha, beta, gamma, delta and kappa. The In2Se3 monolayer is composed of vertically stacked Se-In-Se-In-Se quintuple layers, and the layers are connected by van der Waals force. Compared with other two-dimensional materials, In2Se3 has more excellent comprehensive performance, including high response speed and excellent stability under environmental conditions. Therefore, In2Se3 is expected to become a building material for key elements of the next generation of optoelectronic information equipment, and has broad prospects.

[0003] At present, there are many methods for preparing In2Se3 crystal film, including mechanical exfoliation (ME), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), chemical vapor deposition (CVD), electrochemical intercalation (EI) and the like. These preparation methods have problems such as low efficiency, low crystalline quality of the prepared sample, and inability to synthesize inch-level In2Se3 crystal film. The conversion of multiple phases (beta' and alpha phase) of In2Se3 has attracted widespread attention. These different phases differ in structure and properties, so studying their mutual conversion is of great significance to understanding and regulating the performance of In2Se3 material.

[0004] In the currently reported gas phase synthesis method, the distance between the precursor and the substrate is usually far (generally greater than 10 cm), which leads to instability of the gas source supply. In addition, due to the problem of uneven concentration gradient distribution in the evaporation process of gaseous precursors, it is difficult to realize large-area continuous growth of thin films on the substrate. At present, it is still a great challenge to grow large-area In2Se3 film and phase-controllable conversion. SUMMARY

[0005] In view of the defect that the traditional preparation method can only obtain small-size In2Se3 nanosheet, the purpose of the present application is to provide a method for preparing large-area two-dimensional In2Se3 film crystal material based on a rapid cooling chemical vapor deposition method, a product prepared by the method and application, which solves or at least partially solves the above technical defects existing in the prior art. The gas phase synthesis method provided by the present application is used for preparing inch-level two-dimensional In2Se3 film crystal material, and the method aims to realize synthesis of two-dimensional In2Se3 film material with controllable phase, large size, uniform thickness, ultra-thin and high crystalline quality by controlling rapid cooling and controllable phase synthesis.

[0006] In order to achieve the above first object of the present application, the present application provides a method for preparing a large-area two-dimensional indium selenide film (alpha phase or beta' phase) crystal material based on a rapid cooling chemical vapor deposition method.

[0007] The large area in the present application refers to the size of the prepared two-dimensional indium selenide film being inch level.

[0008] In one aspect, the present application provides a method for preparing a large-area two-dimensional beta' phase indium selenide (In2Se3) film crystal material based on a rapid cooling chemical vapor deposition method, specifically, placing a reaction source material alpha-In2Se3 powder and a growth substrate into a quartz boat, and placing the growth substrate at a position 2.5-3.5 mm above the source material; then placing the quartz boat into a high-temperature heating zone in a chemical vapor deposition system growth chamber, heating to 750-850℃ under inert gas conditions for 25-35 min; after the heat preservation is completed, moving the quartz boat out of the high-temperature heating zone and cooling to room temperature with the furnace, thereby obtaining the large-area two-dimensional beta' phase indium selenide (In2Se3) film crystal material.

[0009] Further, in a preferred embodiment of the present application, the growth substrate is a fluorine crystal mica (KMg3AlSi3O 10 F2) sheet.

[0010] Further, in a preferred embodiment of the present application, the growth substrate is placed at a position 3 mm above the source material.

[0011] Further, in a preferred embodiment of the present application, the growth substrate is placed at a position 3 mm above the source material.

[0012] Further, in a preferred embodiment of the present application, the inert gas is high-purity argon, that is, high-purity argon is introduced into the chemical vapor deposition system growth chamber as a carrier gas.

[0013] Further, in a preferred embodiment of the present application, the inert gas is high-purity argon, that is, high-purity argon is introduced into the chemical vapor deposition system growth chamber as a carrier gas.

[0014] Further, in a preferred embodiment of the present application, the inert gas is high-purity argon, that is, high-purity argon is introduced into the chemical vapor deposition system growth chamber as a carrier gas.

[0015] Further, in a preferred embodiment of the present application, the inert gas is high-purity argon, that is, high-purity argon is introduced into the chemical vapor deposition system growth chamber as a carrier gas.

[0016] Further, in a preferred embodiment of the present application, the temperature of the heat preservation is preferably 800 DEG C, and the time of the heat preservation is preferably 30 min.

[0017] In another aspect, the present application also provides a method for preparing a large-area two-dimensional alpha-phase indium selenide (In2Se3) thin film crystal material based on a rapid cooling chemical vapor deposition method, which comprises the following steps: placing a reaction source material alpha-In2Se3 powder and a growth substrate into a quartz boat, wherein the growth substrate is placed at a position 0.5-1.5 mm above the source material; then placing the quartz boat into a high-temperature heating zone in a chemical vapor deposition system growth chamber, heating to 750-850 DEG C under an inert gas condition, and keeping the temperature for 45-55 min; after the heat preservation, removing the quartz boat from the high-temperature heating zone and cooling to room temperature with the furnace, thereby obtaining the large-area two-dimensional alpha-phase indium selenide (In2Se3) thin film crystal material.

[0018] Further, in a preferred embodiment of the present application, the growth substrate is a fluorine crystal mica (KMg3AlSi3O 10 F2) sheet.

[0019] Further, in a preferred embodiment of the present application, the growth substrate is placed at a position 1 mm above the source material.

[0020] Further, in a preferred embodiment of the present application, the pressure in the chemical vapor deposition system growth chamber is 1 Pa.

[0021] Further, in a preferred embodiment of the present application, the inert gas is high-purity argon, that is, high-purity argon is introduced into the chemical vapor deposition system growth chamber as a carrier gas.

[0022] Further, in a preferred embodiment of the present application, the purity of the high-purity argon is 99.99%.

[0023] Further, in a preferred embodiment of the present application, the flow rate of the carrier gas is 200 sccm.

[0024] Further, in a preferred embodiment of the present application, the heating rate is 40 DEG C / min.

[0025] Further, in a preferred embodiment of the present application, the temperature of the heat preservation is preferably 800 DEG C, and the time of the heat preservation is preferably 50 min.

[0026] The second object of the present application is to provide a large-area two-dimensional beta prime phase indium selenide thin film crystal material or a large-area two-dimensional alpha phase indium selenide thin film crystal material prepared by the method.

[0027] The third object of the present application is to provide an application of the large-area two-dimensional beta prime phase indium selenide thin film crystal material or the large-area two-dimensional alpha phase indium selenide thin film crystal material prepared by the method in a ferroelectric transistor and / or a photoelectric detector.

[0028] The present application also provides a ferroelectric transistor comprising the large-area two-dimensional beta prime phase indium selenide thin film crystal material or the large-area two-dimensional alpha phase indium selenide thin film crystal material prepared by the method.

[0029] The present application also provides a photoelectric detector comprising the large-area two-dimensional beta prime phase indium selenide thin film crystal material or the large-area two-dimensional alpha phase indium selenide thin film crystal material prepared by the method.

[0030] Overall, compared with the prior art, the above technical solutions described in the present application have the following beneficial effects:

[0031] 1. Compared with the prior art CVD method in which the distance between the precursor and the substrate is far (generally more than 10 cm), it is difficult to obtain a stable gas source supply, and the concentration gradient distribution of the evaporated gaseous precursor is uneven, resulting in difficulty in obtaining a large-area (inch-level) continuous growth thin film on the substrate. In the method of the present application, the vertical distance between the precursor and the substrate is about 3 mm and about 1 mm. Compared with the distance of more than 10 cm required by the traditional chemical vapor deposition method, this ultra-short transmission distance can provide a stable, uniform and continuous gas source supply on the growth substrate, thereby obtaining a large-size indium selenide thin film.

[0032] 2. The deposition effect of the beta prime phase indium selenide of the present application is easily affected by the growth parameters. By using the scheme of the present application, the reaction parameters such as reaction time, reaction temperature and the distance between the sample and the substrate can be adjusted to adjust the growth of the beta prime phase indium selenide, change the growth thickness and size, etc., to meet various needs of products.

[0033] 3. Compared with the prior art CVD method which is difficult to directly grow an alpha-In2Se3 thin film, by using the method of the present application, a large-area two-dimensional alpha-In2Se3 thin film can be directly obtained by controlling the reaction time.

[0034] 4. The lateral size of the two-dimensional indium selenide thin film prepared by the method of the present application can reach an inch level.

[0035] 5、The application is to make high quality and large size indium selenide film on mica substrate by rapid cooling chemical vapor deposition in argon environment, and to control the growth morphology of the film by reaction temperature and reaction time, etc. Optical microscope (OM), atomic force microscope (AFM) and Raman spectrum (Raman) are used to describe the micro physical properties of the crystal.

[0036] 6、The two-dimensional indium selenide film prepared by the method of the application has high electron mobility, high quality and wide band gap, and the β' and α phases have ferroelectric effect, which has broad prospects in the application of ferroelectric transistors and photodetectors. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0038] Figure 1 is the schematic diagram of the experimental reaction device for preparing inch-level two-dimensional β' phase In2Se3 thin film crystal material according to embodiment 1 of the application;

[0039] Figure 2 is the schematic diagram of the experimental reaction device for preparing inch-level two-dimensional α phase In2Se3 thin film crystal material according to embodiment 2 of the application;

[0040] Figure 3 is the digital camera photo of the inch-level two-dimensional β'-In2Se3 thin film prepared according to embodiment 1 of the application;

[0041] Figure 4 is the digital camera photo of the two-dimensional α-In2Se3 thin film prepared according to embodiment 2 of the application;

[0042] Figure 5 is the optical microscope photo of the two-dimensional β'-In2Se3 thin film prepared according to embodiment 1 of the application;

[0043] Figure 6 is the optical microscope photo of the two-dimensional α-In2Se3 thin film prepared according to embodiment 2 of the application;

[0044] Figure 7 is the Raman spectrum photo of the two phases of In2Se3 thin film prepared according to embodiment 1 and embodiment 2 of the application;

[0045] Figure 8 is the atomic force microscope photo of the β'-In2Se3 thin film prepared according to embodiment 1 of the application;

[0046] Figure 9 is an atomic force microscope image of the α-In2Se3 thin film prepared in Example 2;

[0047] Figure 10 is an atomic force microscope image of the ordered wrinkle of the α-In2Se3 thin film prepared in Example 2;

[0048] Figure 11 (a)-(f) are digital camera images of the In2Se3 thin film prepared in Example 3 of the present application at different reaction times (5, 10, 20, 30, 40 and 50 minutes), in order;

[0049] Figure 12 (a)-(f) are optical microscope images of the In2Se3 thin film prepared in Example 3 of the present application at different reaction times (5, 10, 20, 30, 40 and 50 minutes), in order;

[0050] Figure 13 (a)-(d) are optical microscope images of the In2Se3 thin film grown in Example 4 of the present application at different reaction temperatures (600, 700, 800 and 900 °C), in order;

[0051] Figure 14 is a digital camera image of the In2Se3 thin film prepared in Example 2 at a vertical distance of 1 mm;

[0052] Figure 15 is an atomic force microscope image of the In2Se3 thin film prepared in Example 5 at (a) a reaction time of 30 minutes, a source material to substrate distance of 1 mm; (b) a reaction time of 30 minutes, a source material to substrate distance of 3 mm; (c) a reaction time of 50 minutes, a source material to substrate distance of 1 mm; (d) a reaction time of 50 minutes, a source material to substrate distance of 3 mm;

[0053] Figure 16 is a contrast curve of the optoelectronic device of the In2Se3 thin film prepared in Example 2 of the present application at different light intensities;

[0054] Figure 17 is a curve of the photoresponsivity and photodetectivity of the optoelectronic device of the In2Se3 thin film prepared in Example 2 of the present application;

[0055] Figure 18 is a curve of the external quantum efficiency of the optoelectronic device of the In2Se3 thin film prepared in Example 2 of the present application.

[0056] Figure 19 is a FET transfer characteristic curve of the α-In2Se3 prepared in Example 2. DETAILED DESCRIPTION

[0057] This invention provides a synthesis method for preparing large-area two-dimensional indium selenide thin films (α and β′ phases) based on a rapid cooling chemical vapor deposition method.

[0058] This invention grows β′ phase In2Se3 thin films by rapid cooling chemical vapor deposition: the growth substrate is placed directly above the source material α-In2Se3 powder, and the vertical distance between the source material and the substrate is controlled to be about 3 mm, and the reaction time is about 30 minutes.

[0059] This invention grows α-phase In2Se3 thin films by rapid cooling chemical vapor deposition: the growth substrate is placed directly above the source material α-In2Se3 powder, and the vertical distance between the source material and the substrate is controlled to be about 1 mm, and the reaction time is about 50 minutes.

[0060] It should be noted that the source material used in this invention is α-In₂Se₃ powder. Under an argon atmosphere, the synthesis of the two phases (β′ and α) of In₂Se₃, as well as the area and thickness of the deposited film, are controlled by chemical vapor deposition. The source material mass is 200 mg, the target temperature is 800℃, and the reaction time is 30 minutes. One end of an iron wire is fixed to a quartz boat, and the other end is attracted to it with a magnet. The boat is placed inside a quartz tube, and another magnet is placed at a corresponding position outside the tube. The attraction between the magnets is used to move the quartz boat. By controlling the reaction time, the synthesis of the two phases (α- and β′-In₂Se₃) of the In₂Se₃ film can be controlled. The source material is laid flat on the bottom of the quartz boat, and a fluorinated mica substrate is placed directly above the source material. When the vertical distance between the source material and the substrate is 3 mm, a large area of ​​β′-In₂Se₃ film can be deposited on the mica substrate by chemical vapor deposition. By controlling the source material mass to 200 mg, the reaction time to 50 minutes, and the distance between the source material and the substrate to 1 mm, a large-area α-In₂Se₃ thin film was deposited on a mica sheet via chemical vapor deposition. The growth area and thickness of the indium selenide (ILS) film were controlled by adjusting the temperature, reaction time, and the distance between the source material and the substrate. The film grown at a reaction time of 30 minutes had a smaller area and thinner thickness than the film grown at a reaction time of 50 minutes. Optical micrographs of the α-In₂Se₃ film revealed angular wrinkles. These wrinkles were caused by interfacial compressive stress due to the difference in thermal expansion coefficients between mica and ILS during the cooling process from high temperature to room temperature. The stress release led to wrinkle formation in the ILS film. Since ILS has a 2H (hexagonal) structure, the included angles of the wrinkles were 60° or 120°, resulting in ordered wrinkles.

[0061] The two-dimensional indium selenide thin film obtained by this invention is a high-quality semiconductor crystal with high electron mobility and a wide bandgap (1.39 eV), which has broad application prospects in photodetectors.

[0062] It should be noted that the short distance (vertical distance 1-3 mm) of the source material and the growth substrate in the present application provides a stable, uniform and continuous gas source supply for the substrate deposition of indium selenide, thereby obtaining a large-size two-dimensional indium selenide crystal material.

[0063] It should be noted that the phase of the two-dimensional indium selenide thin film crystal material in the present application is controllable, and the lateral size can reach an inch level.

[0064] It should be noted that the source material used in the present application is alpha-In2Se3 powder, which is grown by chemical vapor deposition. After the end of the heat preservation and the start of the cooling, the quartz boat in the quartz tube is slowly dragged out of the high-temperature heating zone by moving the magnet, and the thin film crystal material is rapidly cooled to obtain better crystallinity.

[0065] It should be noted that in the preferred embodiment of the present application, the temperature range of the high-temperature heating zone is set to 800℃.

[0066] It should be noted that in the preferred embodiment of the present application, the growth substrate is fluorine crystal mica.

[0067] It should be noted that in the preferred embodiment of the present application, the pressure in the reaction area is about 1 Pa.

[0068] The present application also provides a two-dimensional indium selenide crystal material prepared by the above preparation method, which is a high-quality crystal with high electron mobility (53 cm 2 V -1 S -1 ) and has ferroelectric effect of beta' and alpha phases.

[0069] The present application controls the synthesis of indium selenide (alpha / beta' phase) by controlling the reaction time of chemical vapor deposition. Since the linear expansion coefficient of indium selenide is different from that of fluorine crystal mica sheet, during the process of cooling from high temperature to room temperature, due to the different thermal expansion coefficients of mica and indium selenide, the interface pressure stress acts, the stress is released, and the ordered wrinkles of the indium selenide thin film are formed. The structure of indium selenide is hexagonal symmetry, so the included angle of the wrinkles is 60° or 120°.

[0070] The two-dimensional indium selenide thin film crystal material prepared by the above method of the present application also belongs to the protection scope of the present application.

[0071] The present application will be further described in detail through the following implementation cases. The present implementation case is implemented on the premise of the present application technology, and the detailed implementation mode and specific operation process are given to illustrate the creativity of the present application, but the protection scope of the present application is not limited to the following implementation cases.

[0072] The equipment and raw materials used in the present application can be purchased from the market or are commonly used in the art. The methods in the following examples are conventional methods in the art, unless otherwise specified.

[0073] The fluorine crystal mica (KMg3AlSi3O 10 F2) used in the following examples is commercially available from Changchun Taiyuan Fluorine Crystal Mica Co., Ltd.

[0074] Example 1

[0075] The method of the present embodiment for preparing large-area two-dimensional β'-phase indium selenide (β'-In2Se3) thin film crystal material based on a rapid cooling chemical vapor deposition method comprises the following steps:

[0076] Figure 1 is a cross-sectional view of an experimental device for preparing an inch-level two-dimensional β'-In2Se3 thin film crystal material according to the present application. The deposition equipment is a CVD furnace, which is divided into a high-temperature heating zone and a growth substrate. 200 mg of α-In2Se3 powder is placed in a quartz boat in the high-temperature heating zone and evenly spread. A fluorine crystal mica (KMg3AlSi3O 10 F2) sheet is used as the growth substrate and placed directly above the source material, with the vertical distance between the source material and the substrate controlled within a small range (3 mm). One end of an iron wire is fixed to the quartz boat, and the other end is attracted to the upper surface by a magnet. The iron wire and the magnet are placed in the quartz tube, and another magnet is placed at the corresponding position outside the quartz tube. The quartz boat is moved using the attractive force between the two magnets. Before the reaction, the air is first evacuated, and pure argon gas with a purity of 99.99% is introduced into the quartz tube for 1 hour to remove the air. The target temperature of the high-temperature heating zone is set to 800°C. The holding time after reaching the target temperature is 30 minutes. The heating rate is 40°C / min. After the holding time ends, the quartz boat is slowly pulled out of the heating zone by the magnet, and the product is cooled to room temperature with the furnace. A two-dimensional β'-phase In2Se3 thin film with an area of 2.5*1 cm 2 is obtained on the mica substrate.

[0077] Example 2

[0078] The method of the present embodiment for preparing large-area two-dimensional α-phase indium selenide (α-In2Se3) thin film crystal material based on a rapid cooling chemical vapor deposition method is basically the same as that of Example 1, with the only difference being that the vertical distance between the source material and the substrate in the present embodiment is 1 mm, and the holding time is 50 minutes. The rest of the preparation process and parameters are the same.

[0079] Example 3

[0080] The preparation method of the indium selenide film of the present example is basically the same as that of Example 2, with the only difference being that the indium selenide film of the present example is grown by controlling different reaction times (5, 10, 20, 30, 40 and 50 minutes).

[0081] Example 4

[0082] The preparation method of the indium selenide film of the present example is basically the same as that of Example 2, with the only difference being that the indium selenide film of the present example is grown by controlling different reaction temperatures (600, 700, 800 and 900°C).

[0083] Example 5

[0084] The preparation method of the indium selenide film of the present example is basically the same as that of Example 2, with the only difference being that the indium selenide film of the present example is grown by controlling different reaction times and different distances between the source material and the substrate.

[0085] Analysis of experimental results

[0086] The macroscopic morphology of the In2Se3 film prepared in Example 1 was recorded by a camera, and the results are shown in Figure 3 From the photograph, it can be seen that the size of the In2Se3 film grown on the transparent mica sheet is about 1 inch in length, and the color is dark red.

[0087] The micro-morphology of the two-phase In2Se3 films prepared in Examples 1-2 was characterized by an optical microscope, and the results are shown in Figures 5-6 From the optical microscope image, it can be seen that the two-phase In2Se3 films are both continuous and large in size.

[0088] From the Raman spectrum of the two-phase In2Se3 films of Figure 7 , it can be seen that the wave peaks of a-In2Se3 are at 104, 181 and 191, and the wave peaks of β'-In2Se3 are at 110.

[0089] From the atomic force microscope image of the two-phase In2Se3 films of Figures 8-9 , it can be seen that the films are continuous and smooth in surface without protrusions and particles. The thickness of the β'-In2Se3 prepared in Example 1 is 6.8 nm, and the thickness of the a-In2Se3 prepared in Example 2 is 55 nm.

[0090] From the two-dimensional a-In2Se3 film of Figure 10 , the crack thickness of the ordered wrinkle is 173 nm.

[0091] According to Example 3, from the digital camera images of the indium selenide films of Figure 11 , it can be seen that as the reaction time is prolonged, the film area is increasing, and the area is from 0 cm 2 to 1 cm2 .

[0092] According to Example 3, from Figure 12 From the optical microscopic images of the indium selenide thin film, it can be seen that as the reaction time increases, the continuity of the film also increases, and the color changes from light white to dark red.

[0093] According to Example 4, from Figure 13 Based on the temperature gradient micrographs of the indium selenide thin film, 800℃ is the optimal temperature.

[0094] from Figure 14 Based on digital camera photos showing a distance of 1 mm between the source material and the substrate, samples deposited at a distance of 1–3 mm exhibited the best crystallinity and the highest degree of continuity.

[0095] According to Example 5, from Figure 15 Based on the AFM plots showing different reaction times and different distances between the source material and the substrate, the film thickness increases with increasing reaction time.

[0096] Application Examples

[0097] First, a mica sheet with a two-dimensional β′ phase In₂Se₃ thin film was spin-coated with a layer of PMMA solution at 2000 rpm. Then, the PMMA-coated sample was baked on a hot plate at 80°C for 5 minutes to evaporate the organic solvent in the PMMA, thus solidifying it into a solid film. Next, adhesive tape was attached around the sample, and the sample was immersed in deionized water. Using the surface tension of the water, the PMMA film and mica were separated using tweezers. The PMMA film with the sample was then transferred to a Si / SiO₂ substrate and baked on a hot plate at 45°C for 10 minutes to completely evaporate the water. After dissolving the PMMA in acetone, the In₂Se₃ thin film was transferred onto a silicon wafer.

[0098] The β′ phase In₂Se₃ thin film prepared in Example 1 was transferred to a substrate with an area of ​​1.5 x 1.5 cm using the method described above. 2The silicon wafer was covered with a copper mesh on the sample, and the area of the silicon wafer without the sample was pasted with conductive glue to prevent gold deposition. The gold electrode with a thickness of 60 nm was deposited by a film coating machine to construct a photodetector. The test was carried out in a vacuum environment in a probe station (Mapu vacuum probe station) by a semiconductor analyzer (Keithley 4200). First, the probe was gently pressed against the gold electrode of the device, then the dark current and photocurrent of the device were tested, and finally the responsivity, response and external quantum efficiency of the device were calculated according to the formula. The two Au electrodes above In2Se3 were used as source and drain, respectively, and the bottom Si electrode was used as gate. The ferroelectric transition characteristic curve was tested by scanning the voltage of the gate from -60V to 60V with a step of 1.2V, and applying a source-drain voltage of 1V, 3V and 5V between the source and drain, respectively

[0099] From Figure 16 The two-dimensional In2Se3 thin film photodetector has a good light response characteristic, as can be seen from the light response curve under the irradiation of 405nm laser with different light intensities (1.45*10 - 4 mW / cm 2 ~1.45*10 2 mW / cm 2 , the photocurrent increases continuously with the increase of light intensity.

[0100] Figure 17 The responsivity and detectivity of the two-dimensional In2Se3 thin film photodetector are important parameters of SBPD, and their values directly determine the detection ability of the device and reflect the sensitivity of SBPD to ultraviolet light. According to the calculation formula of and , the R and D* values of the two-dimensional In2Se3 photodetector can be calculated. When the light intensity rises from 1*10 -4 mW / cm 2 to 1*10 2 mW / cm 2 , the responsivity decreases from 749.19A / W to 0.01381A / W, and the detectivity decreases from 1.97*10 14 Jones to 3.63*10 9 Jones. From the data, it can be seen that the responsivity and detectivity decrease, which shows that the photodetector has better responsivity and detectivity when the light intensity is weak, which is helpful for the detection of weak light.

[0101] From Figure 18 The external quantum effect of the two-dimensional In2Se3 thin film photodetector reached 365012%, which showed that the photodetector had good solar blind detection ability.

[0102] From Figure 19 The transfer characteristic curves of the ferroelectric at different source-drain voltages, obtained by scanning the gate voltage from -40 to 40 V, have good gate voltage control function.

[0103] Those skilled in the art will easily understand that the above description is only one of the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing large-area two-dimensional α-phase In₂Se₃ thin film crystal materials based on rapid cooling chemical vapor deposition, characterized in that: The reaction source material α-In2Se3 powder and a growth substrate are placed in a quartz boat, the growth substrate is placed 0.5-1.5 mm above the source material; then the quartz boat is placed in a high-temperature heating area in a chemical vapor deposition system growth chamber, heated to 750-850 ℃ under inert gas conditions for 45-55 min; after the heat preservation is completed, the quartz boat is removed from the high-temperature heating area and cooled to room temperature with the furnace, and the large-area two-dimensional α-phase In2Se3 thin film crystal material is obtained.

2. The method of claim 1, wherein: The growth substrate is a fluorine crystal mica sheet.

3. The method of claim 1, wherein: The inert gas is high-purity argon, and the flow rate of the high-purity argon is 100-300 sccm.

4. The method of claim 1, wherein: The heating rate is 30-50 ℃ / min.

5. The method of claim 1, wherein: The heat preservation temperature is preferably 800 ℃.

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