A method for preparing heterostructure by epitaxial growth and its product and application

Abstract

The present invention discloses a method for preparing a heterostructure by epitaxial growth, its product and application, belonging to the technical field of two-dimensional material photodetectors. The present invention uses an in-situ growth technique to epitaxially grow two-dimensional In2S3 nanosheets on two-dimensional WS 2(1‑x) WSe 2x alloy nanosheets to obtain a WS 2(1‑x) WSe 2x / In2S3 heterostructure with a super-clean heterointerface, and then uses the WS 2(1‑x) WSe 2x / In2S3 heterostructure with a super-clean heterointerface obtained by epitaxial growth to construct a high-performance WS 2(1‑x) WSe 2x / In2S3 photodetector. Through experiments, it is measured that its on / off ratio is as high as 1.19×10 5 .

Description

Technical Field

[0001] The present invention relates to the technical field of two-dimensional material photoelectric detectors, and in particular to a method for preparing a heterostructure by epitaxial growth, and a product and application thereof. Background Art

[0002] Since the discovery of graphene in 2004, the field of two-dimensional materials has experienced rapid development. So far, a variety of two-dimensional materials with different properties have been discovered, covering various types such as insulators, semiconductors and metals. These materials have opened up new paths for scientific research and technological innovation with their unique physical and chemical properties. Two-dimensional materials are widely believed to have great application prospects in electronics, optoelectronics and energy due to their excellent mobility, transparency and flexibility. For example, field-effect transistors based on semiconductor two-dimensional materials have shown superior performance compared to traditional silicon-based field-effect transistors. By stacking different two-dimensional materials through van der Waals forces, heterostructures with novel physical properties can be formed. These heterostructures not only provide convenience in material design, but also show great application potential in electronics, optoelectronics and energy.

[0003] Nevertheless, current research on 2D heterostructures is often accompanied by wet or dry transfer processes, which inevitably involve the problem of polymer contamination at the heterointerface. Therefore, the precise fabrication of artificial heterostructures with clean interfaces remains a challenge. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a heterostructure by epitaxial growth and a product and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a method for preparing a heterostructure by epitaxial growth, wherein the heterostructure is WS 2(1-x) Wlq 2x / In2S3 heterostructure, the method for preparing the heterostructure by epitaxial growth comprises the following steps:

[0007] In2S3 powder is used as the reactant, S powder is used as the supplement, inert gas is used as the carrier gas, and two-dimensional WS 2(1-x) Wlq 2x Alloy nanosheets were used as supports and deposited on the WS by bidirectional gas flow. 2(1-x) Wlq 2x Two-dimensional In2S3 nanosheets are epitaxially grown on the surface of the alloy nanosheets to obtain the WS 2(1-x) Wlq 2x / In2S3 heterostructure.

[0008] The present invention realizes WS by epitaxial growth (van der Waals epitaxy technology) 2(1-x) Wlq 2x / In2S3 heterostructure stacking, i.e. in situ construction of WS 2(1-x) Wlq 2x / In2S3 heterostructure. Compared with the traditional heterostructure that needs to be transferred, it reduces the contact with PVA, PMMA, acetone and other substances, and its heterostructure interface is cleaner, reducing the impact of harmful substances and achieving performance improvement.

[0009] The function of S powder is to supplement S atoms and improve the crystallinity of In2S3.

[0010] Furthermore, the WS 2(1-x) Wlq 2x The / In2S3 heterostructure is a heterostructure with an ultra-clean heterointerface. The ultra-clean heterointerface means that compared with the traditional heterostructure that needs to be constructed by dry transfer, the present invention avoids the residue of pollutants such as PVA at the interface of the heterostructure.

[0011] Furthermore, the bidirectional airflow physical vapor deposition step includes: exhausting the air with an inert gas at a flow rate of 120-150 sccm, with the air flow direction from the carrier to the reactant, then adjusting the flow rate to 100 sccm, and heating to 900-930°C, adjusting the air flow direction from the reactant to the carrier, and keeping warm for 10-15 minutes.

[0012] Furthermore, after the insulation is completed, a step of cooling to room temperature is also included; the flow rate of the inert gas during the insulation and cooling processes is 100 sccm.

[0013] The flow rate of the inert gas, the temperature of the heating source, and the distance between the carrier and the reactants and supplements can limit the formation of In2S3 in the two-dimensional WS 2(1-x) Wlq 2x Moreover, by changing the flow rate of the inert gas, the temperature of the heating source, and the distance between the support and the reactants and supplements, the epitaxial growth of the alloy nanosheets can be achieved in the two-dimensional WS. 2(1-x) Wlq 2x Two-dimensional In2S3 nanosheets of different sizes and thicknesses were epitaxially grown on the surface of the alloy nanosheets.

[0014] Furthermore, the distance between the carrier and the In2S3 powder is 10 cm; the distance between the carrier and the S powder is 19~20 cm.

[0015] Furthermore, the In2S3 powder and the S powder are on the same side of the carrier.

[0016] Furthermore, the heating rate is 22.5-23.25°C / min.

[0017] Furthermore, the two-dimensional WS 2(1-x) Wlq 2x The alloy nanosheets are prepared by physical vapor deposition with bidirectional airflow, the steps comprising: mixing WS2 and WSe2 as reactants, using an inert gas as a carrier gas, and using a SiO2 / Si substrate as a carrier, and preparing a two-dimensional WS on the surface of the carrier by physical vapor deposition with bidirectional airflow. 2(1-x) Wlq 2x Alloy nanosheets.

[0018] Furthermore, the two-dimensional WS 2(1-x) Wlq 2x The value of X in the alloy nanosheets ranges from 0 to 1 and is not 0. X represents the mass ratio of WS2 and WSe2, that is, in terms of mass ratio, WS2:WSe2=1-x:x.

[0019] Furthermore, the physical vapor deposition step of the bidirectional airflow includes: exhausting the air with an inert gas at a flow rate of 120~150sccm, the air flow direction is from the carrier to the reactant, then adjusting the flow rate to 30~40sccm, and heating to 1100~1130°C at a heating rate of 10~13°C / min, then adjusting the air flow direction from the reactant to the carrier, and adjusting the flow rate to 100~120sccm, keeping warm for 8~15min, and finally adjusting the flow rate to 20~30sccm, and cooling to room temperature.

[0020] Furthermore, the SiO2 surface of the SiO2 / Si substrate faces upward.

[0021] Furthermore, the distance between the carrier (SiO2 / Si substrate) and the reactant is 8-10 cm.

[0022] Technical solution 2 of the present invention: WS prepared by the above-mentioned method of preparing heterostructure by epitaxial growth 2(1-x) Wlq 2x / In2S3 heterostructure.

[0023] The third technical solution of the present invention: the above-mentioned WS 2(1-x) Wlq 2x Application of / In2S3 heterostructure in the preparation of high-performance photodetectors.

[0024] Furthermore, the high-performance photodetector is a gain-type photodetector.

[0025] Technical solution 4 of the present invention: a high-performance photoelectric detector, using the above-mentioned WS2(1-x) Wlq 2x / In2S3 heterostructure as photosensitive material.

[0026] Furthermore, the high-performance photodetector has an ultra-clean heterointerface, that is, the high-performance photodetector is a high-performance photodetector with an ultra-clean heterointerface.

[0027] Technical solution 5 of the present invention: The method for preparing the above-mentioned high-performance photodetector comprises the following steps:

[0028] In the WS 2(1-x) Wlq 2x The high-performance photodetector is obtained by spin-coating photoresist on the surface of the / In2S3 heterostructure, aligning, exposing and developing the plate through a photolithography machine, and then plating titanium / gold electrodes.

[0029] The present invention discloses the following technical effects:

[0030] The present invention adopts in-situ growth technology to grow the two-dimensional WS 2(1-x) Wlq 2x Epitaxial growth of two-dimensional In2S3 nanosheets on alloy nanosheets to obtain WS with ultra-clean heterogeneous interface 2(1-x) Wlq 2x / In2S3 heterostructure, and then use the epitaxially grown WS with ultra-clean heterointerface 2(1-x) Wlq 2x / In2S3 heterostructure, constructing high-performance WS 2(1-x) Wlq 2x / In2S3 photodetector, the light on / off ratio is as high as 1.19×10 5 . BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 For the present invention, epitaxial growth of two-dimensional WS 2(1-x) Wlq 2x Schematic diagram of the device for / In2S3 heterostructure;

[0033] Figure 2 WS prepared in Example 1 2(1-x) Wlq 2xOptical microscope image of / In2S3 heterostructure (the scale bar in the figure is 20μm), where (a)-(c) are the right, middle and left areas of the carrier substrate, respectively;

[0034] Figure 3 WS prepared in Example 1 2(1-x) Wlq 2x PL Mapping of / In2S3 heterostructure at 668nm;

[0035] Figure 4 WS prepared in Example 1 2(1-x) Wlq 2x Atomic force microscope test images of In2S3 / In2S3 heterostructure, where (a)-(c) are the right, middle, and left areas of the substrate, respectively;

[0036] Figure 5 WS prepared in Example 1 2(1-x) Wlq 2x / Raman shift map of In2S3 heterostructure;

[0037] Figure 6 WS prepared in Comparative Example 1 2(1-x) Wlq 2x Optical microscopy image of / In2S3 heterostructure (the scale bar in the figure is 20μm);

[0038] Figure 7 WS prepared in Comparative Example 2 2(1-x) Wlq 2x Optical microscopy image of / In2S3 heterostructure (the scale bar in the figure is 20μm);

[0039] Figure 8 WS prepared in Comparative Example 3 2(1-x) Wlq 2x Optical microscopy image of / In2S3 heterostructure (the scale bar in the figure is 20μm);

[0040] Fig. 9 The optical microscope images before and after epitaxial growth in Comparative Example 4 (the scale bar in the figure is 20 μm), wherein (a) is before epitaxial growth, and (b) is after epitaxial growth;

[0041] Fig.10 Optical microscope images before and after epitaxial growth in Comparative Example 5 (the scale bar in the figure is 20 μm), wherein (a) is before epitaxial growth, and (b) is after epitaxial growth;

[0042] Fig.11 This is an optical microscope image of the photodetector prepared in Application Example 1 (the scale bar in the image is 20 μm);

[0043] Fig.12 This is an optical microscope image of the photodetector prepared in comparative application example 1 (the scale bar in the image is 20 μm);

[0044] Fig.13 This is an atomic force microscope test image of In2S3 of the photodetector prepared in Application Example 1;

[0045] Fig.14 This is an atomic force microscope test image of In2S3 of the photodetector prepared in comparative application example 1;

[0046] Fig.15 This is a Kelvin probe force microscope test image of the photodetector prepared in Application Example 1;

[0047] Fig.16 This is a Kelvin probe force microscope test image of the photodetector prepared in Comparative Application Example 1;

[0048] Fig.17 The source-drain voltage-current diagram of the photodetector prepared in Application Example 1 before and after irradiation with light in the 405nm band;

[0049] Fig.18 The source-drain voltage-current diagram of the photodetector prepared in comparative application example 1 before and after illumination in the 405nm band. DETAILED DESCRIPTION

[0050] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0051] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0052] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0053] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0054] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0055] As a first aspect of the present invention, the present invention provides a method for preparing a heterostructure by epitaxial growth, wherein the heterostructure is WS 2(1-x) Wlq 2x / In2S3 heterostructure, the method for preparing the heterostructure by epitaxial growth comprises the following steps:

[0056] In2S3 powder is used as the reactant, S powder is used as the supplement, inert gas is used as the carrier gas, and two-dimensional WS 2(1-x) Wlq 2x Alloy nanosheets were used as supports and deposited on the WS by bidirectional gas flow. 2(1-x) Wlq 2x Two-dimensional In2S3 nanosheets are epitaxially grown on the surface of the alloy nanosheets to obtain the WS 2(1-x) Wlq 2x / In2S3 heterostructure.

[0057] As a preferred embodiment of the present invention, the method for preparing a heterostructure by epitaxial growth comprises the following specific steps:

[0058] (1) WS2 and WSe2 are mixed as reactants, an inert gas is used as a carrier gas, and a SiO2 / Si substrate is used as a carrier. Two-dimensional WS is prepared on the surface of the carrier by physical vapor deposition with bidirectional gas flow. 2(1-x) Wlq 2x Alloy nanosheets, with two-dimensional WS deposited on the surface 2(1-x) Wlq 2x SiO2 / Si substrate of alloy nanosheets;

[0059] The two-dimensional WS 2(1-x) Wlq 2x The value of X in the alloy nanosheets ranges from 0 to 1 and is not 0;

[0060] The bidirectional gas flow physical vapor deposition step comprises: exhausting air with an inert gas at a flow rate of 120-150 sccm, the gas flow direction is from the carrier to the reactant, then adjusting the flow rate to 30-40 sccm, and heating to 1100-1130° C. at a heating rate of 10-13° C. / min, then adjusting the gas flow direction to the reactant to the carrier, and adjusting the flow rate to 100-120 sccm, keeping the temperature for 8-15 minutes, and finally adjusting the flow rate to 20-30 sccm, and cooling to room temperature;

[0061] The SiO2 surface of the SiO2 / Si substrate faces upward;

[0062] The distance between the support and the reactant is 8 to 10 cm;

[0063] (2) In2S3 powder is used as the reactant, S powder is used as the supplement, inert gas is used as the carrier gas, and two-dimensional WS 2(1-x) Wlq 2x Alloy nanosheets (prepared in step (1)) are deposited with two-dimensional WS 2(1-x) Wlq 2x The alloy nanosheets were deposited on the WS substrate by physical vapor deposition using a bidirectional gas flow. 2(1-x) Wlq 2x Two-dimensional In2S3 nanosheets are epitaxially grown on the surface of the alloy nanosheets to obtain the WS 2(1-x) Wlq 2x / In2S3 heterostructure (obtaining surface deposited WS 2(1-x) Wlq 2x / In2S3 heterostructured SiO2 / Si substrate);

[0064] The bidirectional gas flow physical vapor deposition step comprises: exhausting air with an inert gas at a flow rate of 120-150 sccm, the gas flow direction is from the carrier to the reactant, then adjusting the flow rate to 100 sccm, heating to 900-930°C at a heating rate of 22.5-23.25°C / min, adjusting the gas flow direction to the reactant to the carrier, keeping the temperature for 10-15 minutes, and finally cooling to room temperature;

[0065] The distance between the support and the In2S3 powder is 10 cm; the distance between the support and the S powder is 19-20 cm;

[0066] The In2S3 powder and the S powder are on the same side of the support;

[0067] 2D WS 2(1-x) Wlq 2x The alloy nanosheets face up.

[0068] As a second aspect of the present invention, the present invention provides WS prepared according to the above method for preparing a heterostructure by epitaxial growth. 2(1-x) Wlq 2x / In2S3 heterostructure.

[0069] As a third aspect of the present invention, the present invention provides the WS 2(1-x) Wlq 2x Application of / In2S3 heterostructure in the preparation of high-performance photodetectors.

[0070] As a fourth aspect of the present invention, the present invention provides a high-performance photodetector, using the above-mentioned WS 2(1-x) Wlq 2x / In2S3 heterostructure as photosensitive material.

[0071] As a preferred embodiment of the present invention, the high-performance photodetector has an ultra-clean heterogeneous interface.

[0072] As a fifth aspect of the present invention, the present invention provides a method for preparing the above-mentioned high-performance photodetector, comprising the following steps:

[0073] In the WS 2(1-x) Wlq 2x The high-performance photodetector is obtained by spin-coating photoresist on the surface of the / In2S3 heterostructure, aligning, exposing and developing the plate through a photolithography machine, and then plating titanium / gold electrodes.

[0074] As a preferred embodiment of the present invention, the preparation method comprises the following more specific steps:

[0075] (1) WS2 and WSe2 are mixed as reactants, an inert gas is used as a carrier gas, and a SiO2 / Si substrate is used as a carrier. Two-dimensional WS is prepared on the surface of the carrier by physical vapor deposition with bidirectional gas flow. 2(1-x) Wlq 2x Alloy nanosheets, with two-dimensional WS deposited on the surface 2(1-x) Wlq 2x SiO2 / Si substrate of alloy nanosheets;

[0076] (2) In2S3 powder is used as the reactant, S powder is used as the supplement, inert gas is used as the carrier gas, and two-dimensional WS 2(1-x) Wlq 2x The alloy nanosheets (prepared in step (1)) have two-dimensional WS deposited on their surfaces 2(1-x) Wlq2x The alloy nanosheets were deposited on the two-dimensional WS substrate by physical vapor deposition using bidirectional gas flow. 2(1-x) Wlq 2x Two-dimensional In2S3 nanosheets are epitaxially grown on the surface of the alloy nanosheets to obtain the WS 2(1-x) Wlq 2x / In2S3 heterostructure (obtained with WS deposited on the surface 2(1-x) Wlq 2x / In2S3 heterostructured SiO2 / Si substrate);

[0077] (3) In the WS 2(1-x) Wlq 2x The high-performance photodetector is obtained by spin-coating photoresist on the surface of the / In2S3 heterostructure, aligning, exposing and developing the plate through a photolithography machine, and then plating titanium / gold electrodes.

[0078] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0079] The raw materials used in the specific implementation of the present invention are all commercially available products, among which S powder, WS2 powder and WSe2 powder are all purchased from Aladdin with purities of 99.5%, 99.99% and 99.99% respectively. In2S3 powder is purchased from Alfa Aesar with a purity of 99.997%.

[0080] The room temperature involved in the specific implementation manner of the present invention specifically refers to 20-30°C.

[0081] Figure 1 The epitaxial growth of WS in the specific embodiment of the present invention 2(1-x) Wlq 2x Schematic diagram of the device for / In2S3 heterostructure.

[0082] The distance between the reactant and the substrate, or the distance between the supplement and the substrate in the following embodiments and comparative examples refers to the distance from the reactant or the supplement to the center of the substrate.

[0083] Example 1

[0084] (1) 2D WS 2(1-x) Wlq 2x Preparation of alloy nanosheets:

[0085] S1, mixing WS2 powder and WSe2 powder in a mass ratio of 3:1, stirring evenly, to obtain a reactant;

[0086] S2. Place the reactants and SiO2 / Si substrate at the center (reactants) and edge (substrate) of the heating zone of a horizontal tube furnace with a single temperature zone, with the SiO2 surface of the SiO2 / Si substrate facing upward, and the distance between the reactants and the SiO2 / Si substrate in the center zone is 10 cm;

[0087] S3, first pass nitrogen at a gas flow rate of 150 sccm for 20 minutes to exhaust the air in the quartz tube of the horizontal tube furnace, adjust the flow rate to 40 sccm and then start heating, and uniformly heat for 1.5 hours to 1130°C. The gas flow direction of this step is from the SiO2 / Si substrate to the reactant;

[0088] S4. When the temperature reaches 1130°C, change the nitrogen flow direction from the reactant to the SiO2 / Si substrate, then adjust the flow rate to 120 sccm and keep warm for 12 minutes to make WS 2(1-x) Wlq 2x The alloy begins to grow on the substrate;

[0089] S5. After the insulation is completed, adjust the gas flow rate to 25sccm and reduce WS 2(1-x) Wlq 2x The excess growth was naturally cooled to room temperature, and a two-dimensional WS was prepared on the surface of the SiO2 / Si substrate. 2(1-x) Wlq 2x Alloy nanosheets (X=0.25) with two-dimensional WS deposited on the surface 2(1-x) Wlq 2x SiO2 / Si substrate of alloy nanosheets.

[0090] (2) WS 2(1-x) Wlq 2x Epitaxial growth of In2S3 heterostructures:

[0091] S1. Mix 5 mg of reactant In2S3 powder and two-dimensional WS 2(1-x) Wlq 2x The alloy nanosheet substrate (i.e., the surface prepared in step (1) is deposited with two-dimensional WS 2(1-x) Wlq 2x The SiO2 / Si substrate of the alloy nanosheets was placed in the center (reactant) and edge (substrate) of the heating zone of a horizontal tube furnace with a single temperature zone. 2(1-x) Wlq 2x Two-dimensional WS on alloy nanosheet substrate 2(1-x) Wlq 2x Alloy nanosheets face up, reactants in the center and 2D WS 2(1-x) Wlq 2x The distance between the alloy nanosheet substrate and the substrate is 10 cm; then the supplementary S powder is placed, and the S powder and the two-dimensional WS 2(1-x) Wlq2x The distance between the alloy nanosheet substrate and the S powder and In2S3 powder is 19 cm. 2(1-x) Wlq 2x the same side of the alloy nanosheet substrate;

[0092] S2, first pass nitrogen at a gas flow rate of 150 sccm for 20 minutes to exhaust the air in the quartz tube of the horizontal tube furnace, then adjust the flow rate to 100 sccm and start heating, and heat it uniformly for 40 minutes to 900°C. The gas flow direction in this step is from the reactant to the substrate;

[0093] S3, after the temperature reaches 900℃, keep it warm for 10min, then cool naturally. 2(1-x) Wlq 2x Two-dimensional In2S3 nanosheets were epitaxially grown on the surface of alloy nanosheet substrate to obtain WS 2(1-x) Wlq 2x / In2S3 heterostructure.

[0094] Figure 2 WS prepared in Example 1 2(1-x) Wlq 2x Optical microscope images of / In2S3 heterostructures, where (a)-(c) are the right, middle, and left regions of the substrate, respectively (the side close to the reactants is the left side); Figure 3 WS prepared in Example 1 2(1-x) Wlq 2x PL mapping of / In2S3 heterostructure at 668nm.

[0095] Depend on Figure 2 and Figure 3 It can be seen that the epitaxially grown In2S3 in Example 1 has good uniformity, high crystallinity, and a size of about 20 μm, which is suitable for photodetectors. Moreover, the PL peak at In2S3 is completely quenched, which is more conducive to the separation of photogenerated carriers in photodetector applications, reduces the recombination of photogenerated carriers, and thus improves the responsivity of the photodetector.

[0096] Figure 4 WS prepared in Example 1 2(1-x) Wlq 2x Atomic force microscope test images of In2S3 / In2S3 heterostructure, where (a)-(c) are the right, middle and left areas of the substrate respectively (the side close to the reactant is the left side).

[0097] Depend on Figure 4It can be seen that the epitaxially grown In2S3 in Example 1 has different thicknesses, namely 13nm, 57nm, and 98nm. The epitaxial growth of In2S3 with different thicknesses can be achieved.

[0098] Figure 5 WS prepared in Example 1 2(1-x) Wlq 2x Raman shift map of / In2S3 heterostructure.

[0099] Depend on Figure 5 It can be seen that for a single WS 2(1-x) Wlq 2x The two main Raman peaks of (x=0.25) are located at 262 cm -1 and 409cm -1 , belonging to E1 2g and A respectively 1g ; For single In2S3, at 247cm -1 、306cm -1 and 328cm -1 Raman peaks were found, corresponding to A 1g , A 1g and F 2g It is noteworthy that the above main peaks all appear in the overlapping region, and no shift is observed, indicating that the epitaxially grown heterostructure is of high quality.

[0100] Comparative Example 1

[0101] Compared with Example 1, the only difference is that WS 2(1-x) Wlq 2x During the epitaxial growth of the / In2S3 heterostructure, the gas flow rate is 120 sccm (i.e., the flow rate is adjusted to 120 sccm and then the temperature is started to rise).

[0102] Figure 6 WS prepared in Comparative Example 1 2(1-x) Wlq 2x Optical microscopy image of / In2S3 heterostructure.

[0103] Depend on Figure 6 It can be seen that In2S3 in WS 2(1-x) Wlq 2x The size of the epitaxially grown alloy nanosheets on the substrate is small and dense (3-7 μm in size), which is not conducive to the fabrication of photodetectors.

[0104] Comparative Example 2

[0105] Compared with Example 1, the only difference is that WS 2(1-x) Wlq 2x Reactants and WS in the central region during epitaxial growth of / In2S3 heterostructures2(1-x) Wlq 2x The distance of the alloy nanosheet substrate is 9 cm.

[0106] Figure 7 WS prepared in Comparative Example 2 2(1-x) Wlq 2x Optical microscopy image of / In2S3 heterostructure.

[0107] Depend on Figure 7 It can be seen that In2S3 in WS 2(1-x) Wlq 2x Alloy nanosheets grow epitaxially, but due to being close to the center of the heating source, the lower WS 2(1-x) Wlq 2x Alloy nanosheets are easily damaged and fall off.

[0108] Comparative Example 3

[0109] Compared with Example 1, the difference is that in WS 2(1-x) Wlq 2x No supplementary S powder was used during the epitaxial growth of the / In2S3 heterostructure.

[0110] Figure 8 WS prepared in Comparative Example 3 2(1-x) Wlq 2x Optical microscopy image of / In2S3 heterostructure.

[0111] Depend on Figure 8 It can be seen that In2S3 in WS 2(1-x) Wlq 2x However, due to the lack of sufficient S atoms, the crystal quality of the upper In2S3 layer is poor.

[0112] Comparative Example 4

[0113] (1) Preparation of two-dimensional NiTe2 nanosheets:

[0114] S1, weigh 6 mg Te powder and 2 mg NiCl2 as reactants respectively;

[0115] S2. Place NiCl2 and SiO2 / Si substrates in the center of the heating zone of a horizontal tube furnace with a single temperature zone, place Te powder at the left edge, and place the SiO2 side of the SiO2 / Si substrate downward. The distance between Te powder and NiCl2 and SiO2 / Si substrates is 4 cm.

[0116] S3, first pass nitrogen at a gas flow rate of 150 sccm for 20 minutes to exhaust the air in the quartz tube of the horizontal tube furnace, then adjust the flow rate to 60 sccm and start heating, and uniformly heat for 40 minutes to 550°C. The gas flow direction in this step is from Te powder to SiO2 / Si substrate;

[0117] S4. When the temperature reaches 550°C, keep warm for 10 minutes;

[0118] S5. After the heat preservation is completed, the mixture is naturally cooled to room temperature, and two-dimensional NiTe2 nanosheets are prepared on the surface of the SiO2 / Si substrate, thereby obtaining a SiO2 / Si substrate with two-dimensional NiTe2 nanosheets deposited on the surface.

[0119] (2) Epitaxial growth

[0120] S1. Place 5 mg of reactant In2S3 powder and a two-dimensional NiTe2 nanosheet substrate (i.e., the SiO2 / Si substrate with two-dimensional NiTe2 nanosheets deposited on the surface obtained in step (1)) at the center (reactant) and edge (substrate) of the heating zone of a single-temperature horizontal tube furnace, with the two-dimensional NiTe2 nanosheets of the two-dimensional NiTe2 nanosheet substrate facing upward, and the distance between the reactant in the center and the two-dimensional NiTe2 nanosheet substrate is 10 cm; then place the supplementary S powder, with the distance between the S powder and the two-dimensional NiTe2 nanosheet substrate being 19 cm, and the S powder and In2S3 powder being located on the same side of the two-dimensional NiTe2 nanosheet substrate;

[0121] S2, first pass nitrogen at a gas flow rate of 150 sccm for 20 minutes to exhaust the air in the quartz tube of the horizontal tube furnace, then adjust the flow rate to 100 sccm and start heating, and heat it uniformly for 40 minutes to 900°C. The gas flow direction in this step is from the reactant to the substrate;

[0122] S3. After the temperature reaches 900°C, keep it warm for 10 minutes and then cool it naturally to epitaxially grow two-dimensional In2S3 nanosheets on the surface of the two-dimensional NiTe2 nanosheet substrate.

[0123] Fig. 9 These are optical microscope images before and after epitaxial growth in Comparative Example 4, wherein (a) is before epitaxial growth, and (b) is after epitaxial growth.

[0124] Depend on Fig. 9 It can be seen that the atoms of the lower layer NiTe2 are partially detached at high temperature, and In2S3 cannot grow epitaxially on the NiTe2 substrate.

[0125] Comparative Example 5

[0126] (1) Preparation of two-dimensional In2Se3 nanosheets:

[0127] S1, weigh 5 mg In2Se3 powder as reactant;

[0128] S2. Place the reactants on a flat boat with the mica facing upward, and place the flat boat in the center of the heating zone of a horizontal tube furnace with a single temperature zone;

[0129] S3, first pass nitrogen at a gas flow rate of 200 sccm for 20 minutes to exhaust the air in the quartz tube of the horizontal tube furnace, then adjust the flow rate to 175 sccm and start heating, and uniformly heat for 30 minutes to 835°C;

[0130] S4. When the temperature reaches 835°C, keep it warm for 4 minutes and adjust the gas flow rate to 80 sccm;

[0131] S5. After the heat preservation is completed, the gas flow rate is adjusted to 175 sccm, and the mixture is naturally cooled to room temperature to obtain a two-dimensional In2Se3 nanosheet.

[0132] S6. Spin-coat the surface of the two-dimensional In2Se3 nanosheets prepared on mica with a PMMA solution at a rotation speed of 2000 rpm for 120 seconds. After the spin coating is completed, bake at 100°C for 10 minutes, place in deionized water and slowly tear off the PMMA film with the two-dimensional In2Se3 nanosheets, then stick it on a new SiO2 / Si substrate, heat it on a heating plate at 100°C for 30 minutes, and finally immerse it in acetone for 30 minutes to remove the PMMA film, blow dry with nitrogen, and complete the transfer of the two-dimensional In2Se3 nanosheets to the SiO2 / Si substrate;

[0133] (2) Epitaxial growth

[0134] S1. Place 5 mg of reactant In2S3 powder and a two-dimensional In2Se3 nanosheet substrate (i.e., the SiO2 / Si substrate with two-dimensional In2Se3 nanosheets deposited on the surface obtained in step (1)) at the center (reactant) and edge (substrate) of the heating zone of a single-temperature horizontal tube furnace, with the two-dimensional In2Se3 nanosheets of the two-dimensional In2Se3 nanosheet substrate facing upward, and the distance between the reactant in the center and the two-dimensional In2Se3 nanosheet substrate is 10 cm; then place the supplementary S powder, with the distance between the S powder and the two-dimensional In2Se3 nanosheet substrate being 19 cm, and the S powder and In2S3 powder being located on the same side of the two-dimensional In2Se3 nanosheet substrate;

[0135] S2, first pass nitrogen at a gas flow rate of 150 sccm for 20 minutes to exhaust the air in the quartz tube of the horizontal tube furnace, then adjust the flow rate to 100 sccm and start heating, and heat it uniformly for 40 minutes to 900°C. The gas flow direction in this step is from the reactant to the substrate;

[0136] S3. After the temperature reaches 900°C, keep it warm for 10 minutes and then cool it naturally to epitaxially grow two-dimensional In2S3 nanosheets on the surface of the two-dimensional In2Se3 nanosheet substrate.

[0137] Fig.10 These are optical microscope images before and after epitaxial growth in Comparative Example 5, wherein (a) is before epitaxial growth, and (b) is after epitaxial growth.

[0138] Depend on Fig.10 It can be seen that In2S3 cannot be epitaxially grown on In2Se3 substrate.

[0139] Application Example 1

[0140] The preparation of high-performance photodetectors with ultra-clean heterojunction interfaces is as follows:

[0141] In the product of step (2) of Example 1 (i.e., WS 2(1-x) Wlq 2x WS in SiO2 / Si substrate ( / In2S3 heterostructure) 2(1-x) Wlq 2x The surface of the In2S3 heterostructure is spin-coated with photoresist, and the device pattern is formed after plate alignment, exposure and development by a photolithography machine, and then titanium / gold electrodes are plated to obtain a high-performance photodetector with an ultra-clean heterojunction (the relevant steps are conventional methods in the field and will not be repeated here).

[0142] Fig.11 This is an optical microscope image of the photodetector prepared in Application Example 1.

[0143] Depend on Fig.11 It can be seen that the photodetector is a two-dimensional WS 2(1-x) Wlq 2x Alloy nanosheets are used as the bottom material, two-dimensional In2S3 is used as the upper material, and titanium / gold is used as the source and drain electrodes, which are placed on the two-dimensional WS 2(1-x) Wlq 2x Overlapping positions of alloy nanosheets and two-dimensional In2S3.

[0144] Comparative application example 1

[0145] S1. The product of step (1) of Example 1 (i.e., the surface of which is deposited with WS 2(1-x) Wlq 2x Two-dimensional WS in alloy nanosheets (X=0.25) on SiO2 / Si substrate 2(1-x) Wlq 2x The alloy nanosheets were spin-coated with PMMA solution at a speed of 2000 rpm for 120 s. After the spin coating was completed, they were baked at 100 °C for 10 min and then immersed in BOE solution for 5 min.2(1-x) Wlq 2x The PMMA film of the alloy nanosheet is separated from the substrate, and the separated WS 2(1-x) Wlq 2x The alloy nanosheet / PMMA film was washed with deionized water for three times, then attached to a new SiO2 / Si substrate, heated on a hot plate at 100 °C for 30 min, and finally immersed in acetone for 30 min to remove the PMMA film and dried with nitrogen to complete the two-dimensional WS. 2(1-x) Wlq 2x Transfer of alloy nanosheets to new substrates;

[0146] S2, spin-coat PVA onto the two-dimensional In2S3, then heat it at 110℃ for 4min, and slowly peel it off. The two-dimensional In2S3 is transferred to the PVA film, and then the PVA film with In2S3 is bonded to the WS on the substrate. 2(1-x) Wlq 2x Alloy nanosheets were stacked, heated at 110 °C for 4 min, and then immersed in deionized water at 55 °C for 30 min to remove PVA and achieve In2S3 transfer on WS 2(1-x) Wlq 2x On the alloy nanosheet, a two-dimensional layered WS is formed 2(1-x) Wlq 2x / In2S3 heterostructure;

[0147] S3, in two-dimensional layered WS 2(1-x) Wlq 2x The surface of the / In2S3 heterostructure is spin-coated with photoresist, and a device pattern is formed after alignment, exposure, and development by a photolithography machine, and then titanium / gold electrodes are plated to obtain a photodetector (the relevant steps are conventional methods in the art and will not be repeated here. The operating parameters of Application Example 1 and Comparative Application Example 1 are the same).

[0148] Fig.12 This is an optical microscope image of the photodetector prepared in comparative application example 1.

[0149] Depend on Fig.12 It can be seen that the photodetector is a two-dimensional WS 2(1-x) Wlq 2x Alloy nanosheets are used as the bottom material, two-dimensional In2S3 is used as the upper material, and titanium / gold is used as the source and drain electrodes, which are placed on the two-dimensional WS 2(1-x) Wlq 2x Overlapping positions of alloy nanosheets and two-dimensional In2S3.

[0150] Test Example 1

[0151] Fig.13 This is the atomic force microscope test image of In2S3 of the photodetector prepared in Application Example 1.

[0152] Depend on Fig.13 It can be seen that the thickness of the two-dimensional In2S3 nanosheet of the photodetector prepared in Application Example 1 is 57 nm.

[0153] Fig.14 This is an atomic force microscope test image of In2S3 of the photodetector prepared in comparative application example 1.

[0154] Depend on Fig.14 It can be seen that the thickness of the two-dimensional In2S3 nanosheet of the photodetector prepared in Comparative Application Example 1 is 55 nm, which is not much different from the thickness of In2S3 in Application Example 1, eliminating the influence of thickness on performance.

[0155] Fig.15 This is a Kelvin probe force microscope test image of the photodetector prepared in Application Example 1; Fig.16 This is a Kelvin probe force microscope test image of the photodetector prepared in comparative application example 1.

[0156] Depend on Fig.15 It can be seen that the WS heterostructure grown in situ in Application Example 1 2(1-x) Wlq 2x The potential difference between the alloy and In2S3 is 179mV. Fig.16 It can be seen that compared with the WS of the traditional transfer heterostructure in application example 1 2(1-x) Wlq 2x The potential difference between the alloy and In2S3 is 63mV. Application Example 1 increases it by 116mV, which helps to enhance the separation of photogenerated carriers and improve the responsivity and response speed of the photodetector.

[0157] Fig.17 The source-drain voltage-current diagram of the photodetector prepared in Application Example 1 before and after irradiation with light in the 405nm band; Fig.18 The source-drain voltage-current diagram of the photodetector prepared in comparative application example 1 before and after illumination in the 405nm band.

[0158] Depend on Fig.17 It can be seen that when the source-drain voltage of the photodetector in Application Example 1 is 1V under dark conditions, the current is 1.63×10 -12 A, at an intensity of 101.22 mW / cm 2 Under the 405nm light intensity, the current value at 1V source-drain voltage is 1.95×10 -7 A. By Fig.18 It can be seen that the current of the photodetector of comparative application example 1 is 4.84×10 -12 A, at an intensity of 101.22 mW / cm 2Under the 405nm light intensity, the current value at 1V source-drain voltage is 1.49×10 -8 A. In comparison, the photodetector of Application Example 1 has lower dark current, higher photocurrent, and higher light on / off ratio [I 开 / I 关 =(I 光照 -I 黑暗 ) / I 黑暗 ](I 光照 is the current value obtained under light conditions, I 黑暗 is the current value obtained in the dark) is larger (up to 1.19×10 5 This is due to the in-situ growth of WS 2(1-x) Wlq 2x The ultra-clean heterointerface of the / In2S3 heterostructure is free of interface contamination caused by the traditional two-step transfer method and can more effectively separate photogenerated carriers.

[0159] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a heterostructure by epitaxial growth, characterized in that: The heterostructure is WS 2(1-x) Wlq 2x / In2S3 heterostructure, the method for preparing the heterostructure by epitaxial growth comprises the following steps: In2S3 powder is used as the reactant, S powder is used as the supplement, inert gas is used as the carrier gas, and two-dimensional WS 2(1-x) Wlq 2x Alloy nanosheets were used as supports and deposited on the two-dimensional WS by physical vapor deposition via bidirectional airflow. 2(1-x) Wlq 2x Two-dimensional In2S3 nanosheets are epitaxially grown on the surface of the alloy nanosheets to obtain the WS 2(1-x) Wlq 2x / In2S3 heterostructure; The bidirectional gas flow physical vapor deposition step comprises: exhausting air with an inert gas at a flow rate of 120-150 sccm, the gas flow direction is from the carrier to the reactant, then adjusting the flow rate to 100 sccm, and heating to 90-930°C, adjusting the gas flow direction to the reactant to the carrier, and keeping the temperature for 10-15 minutes; The distance between the support and the In2S3 powder is 10 cm; the distance between the support and the S powder is 19-20 cm; The two-dimensional WS 2(1-x) Wlq 2x The alloy nanosheets are prepared by physical vapor deposition with bidirectional airflow, the steps comprising: mixing WS2 and WSe2 as reactants, using an inert gas as a carrier gas, and using a SiO2 / Si substrate as a carrier, and preparing a two-dimensional WS on the surface of the carrier by physical vapor deposition with bidirectional airflow. 2(1-x) Wlq 2x Alloy nanosheets.

2. The method for preparing a heterostructure by epitaxial growth according to claim 1, characterized in that: The heating rate is 22.5-23.25°C / min.

3. The method for preparing a heterostructure by epitaxial growth according to claim 1, characterized in that: The two-dimensional WS 2(1-x) Wlq 2x The value of X in the alloy nanosheets ranges from 0 to 1 and is not 0.

4. A WS prepared by the method for preparing a heterostructure by epitaxial growth according to any one of claims 1 to 3 2(1-x) Wlq 2x / In2S3 heterostructure.

5. The WS according to claim 4 2(1-x) Wlq 2x Application of / In2S3 heterostructure in the preparation of high-performance photodetectors.

6. A high performance photodetector, characterized in that: The WS according to claim 4 2(1-x) Wlq 2x / In2S3 heterostructure as photosensitive material.

7. The method for preparing a high-performance photodetector according to claim 6, characterized in that: The following steps are involved: In the WS 2(1-x) Wlq 2x The surface of the / In2S3 heterostructure is spin-coated with photoresist, and after alignment, exposure and development by a photolithography machine, titanium / gold electrodes are plated to obtain the high-performance photodetector.

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