Sb2O3 / MX2 heterojunction and preparation and application thereof

Abstract

The invention belongs to the field of preparation of two-dimensional materials, and particularly relates to a preparation method of a Sb2O3 / MX2 heterojunction, which comprises the following steps: arranging a Sb2O3 source in a temperature zone 1 of a vapor deposition tube, and arranging an MX2 two-dimensional material substrate in a temperature zone 2 of the vapor deposition tube; the temperature of the temperature zone 1 is raised to 400-480 DEG C under reverse carrier gas flow in advance; and then the carrier gas flow is converted into the forward direction, so that the volatilized Sb2O3 is subjected to PVD deposition on the MX2 two-dimensional material substrate, and the Sb2O3 / MX2 heterojunction is prepared. The reverse temperature area 2 points to the direction of the temperature area 1, and the forward temperature area 1 points to the direction of the temperature area 2; in the MX2 two-dimensional material, M is a transition metal; and X is S or Se. The invention also discloses the material prepared by the preparation method and application thereof. According to the method disclosed by the invention, the substrate two-dimensional material with high crystallinity and large area can be obtained. Taking a WSe2 single crystal as an example, if one-way airflow (forward airflow) is directly used, the obtained WSe2 single crystal is relatively small in size and is generally less than 100 microns, and the surface of the WSe2 single crystal is non-uniform.

Description

Technical Field

[0001] The present invention belongs to the field of two-dimensional material preparation, and particularly relates to a van der Waals dielectric material, a preparation method thereof, and an application thereof. Technical Background

[0002] Two-dimensional (2D) semiconductors have the characteristics of being atomically thin, having strong gate controllability, having no dangling bonds on the surface, and having high carrier mobility, and are therefore considered to be ideal candidate materials for next-generation electronic devices 1-5 . To build large-scale circuits, it is crucial to integrate high-quality dielectrics on the surface of two-dimensional semiconductors. However, applying the existing state-of-the-art ALD process to two-dimensional semiconductors is challenging because the pristine surface of two-dimensional semiconductors has no dangling bonds and cannot undergo chemical reactions 6-8 . In modern silicon microelectronics, chemical vapor deposition (CVD) has high controllability, can be used for large-scale preparation, and can obtain high-quality van der Waals insulator / semiconductor interfaces, which benefits from its ability to scalably integrate high-quality thin films with well-controlled thicknesses

[0003] Two-dimensional semiconductor transition metal chalcogenides (s-TMDs), such as WSe 2 , have the potential to be used as channel materials for next-generation electronic devices 9-13 . Sub-stoichiometric metal oxides (such as MoO for p-type x 14 and AlO for n-type x or TiO x 15-16 ) have been used as stable doping layers for two-dimensional materials, but doped devices usually suffer from serious degradation of the current on / off ratio and poor SS. These challenges ultimately hinder the realization of two-dimensional transistors with high on-current and good current on / off ratio

[0004] References

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[0018] 14. Cai, Lili, et al. "Rapid flame synthesis of atomically thin MoO 3 down to monolayer thickness for effective hole doping of WSe 2."Nano letters 17.6(2017):3854-3861.

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[0020] 16.Leonhardt,Alessandra,et al."Material-Selective Doping of 2DTMDCthrough Al x O y Encapsulation."ACS applied materials&interfaces 11.45(2019):42697-42707. Summary of the Invention

[0021] Regarding the problem that there is no Sb 2 O 3 / MX 2 heterojunction with high crystallinity and controllable thickness in the prior art, the first object of the present invention is to provide a method for preparing an Sb 2 O 3 / MX 2 heterojunction, aiming to prepare an Sb 2 O 3 / MX 2 heterojunction with high-performance crystallinity and ultra-thin thickness.

[0022] The second object of the present invention is to provide the Sb 2 O 3 / MX 2 heterojunction prepared by the preparation method and its preparation application in optoelectromagnetic devices.

[0023] The third object of the present invention is to provide a device containing or prepared from the Sb 2 O 3 / MX 2 heterojunction.

[0024] Sb 2 O 3 / MX 2 The preparation method of the heterojunction, the Sb2 O 3 The source is set in the temperature zone 1 of the vapor deposition tube, and the MX 2 The two-dimensional material substrate is arranged in the temperature zone 2 of the vapor deposition tube;

[0025] In advance, the temperature of temperature zone 1 is raised to 400-480°C under reverse carrier gas flow; then the carrier gas flow is changed to forward flow to make the volatilized Sb 2 O 3 In MX 2 The two-dimensional material substrate is subjected to PVD deposition to obtain the Sb 2 O 3 / MX 2 Heterojunction;

[0026] The reverse direction refers to the direction from temperature zone 2 to temperature zone 1, and the forward direction refers to the direction from temperature zone 1 to temperature zone 2;

[0027] The MX 2 In the two-dimensional material, the M is a transition metal; and the X is S or Se.

[0028] The present invention innovatively adopts the current conversion technology to realize Sb 2 O 3 / MX 2 Heterojunction synthesis, so that in MX 2 Highly crystallinity and controllable thickness of Sb formed on the surface of two-dimensional materials 2 O 3 , Sb with excellent morphology and excellent performance can be obtained 2 O 3 / MX 2 Heterojunction.

[0029] In the present invention, the MX 2 In the two-dimensional material, the M is W or Mo.

[0030] In the present invention, the MX 2 Two-dimensional materials can be synthesized based on conventional means, for example, they can be synthesized by conventional PVD or CVD methods.

[0031] For example, optional PVD-synthesized MX 2 The steps for two-dimensional materials are: MX 2 Heat to the volatilization temperature, then change the carrier gas to positive gas flow, and make MX 2 Deposited on a substrate to obtain the s-TMD substrate two-dimensional material; the reverse direction refers to the substrate to MX 2 Direction; positive direction refers to MX 2 Direction to the base.

[0032] Preferably, the MX 2 has a volatilization temperature of 1160 - 1200 °C; and a deposition temperature of 840 - 900 °C.

[0033] Preferably, the MX 2 is WSe 2 , which has a volatilization temperature of 1165 - 1185 °C; and a deposition temperature of 840 - 850 °C;

[0034] Alternatively, the MX 2 is WS 2 , which has a volatilization temperature of 1180 - 1200 °C; and a deposition temperature of 850 - 860 °C;

[0035] Alternatively, the MX 2 is MoS 2 , which has a volatilization temperature of 1195 - 1200 °C; and a deposition temperature of 860 - 865 °C;

[0036] Alternatively, the MX 2 is MoSe 2 , which has a volatilization temperature of 1195 - 1200 °C; and a deposition temperature of 860 - 865 °C;

[0037] The carrier gas is a protective gas, and the flow rates of the carrier gas in the forward and reverse directions are both 70 - 85 sccm;

[0038] The deposition time is 1 - 8 min, and further preferably 2 - 5 min.

[0039] The MX 2 two-dimensional material can also be prepared by a conventional CVD method. For example, taking the MX 2 as MoS 2 as an example, a Mo oxide source and a sulfur source can be heated separately and subjected to CVD deposition to prepare the MoS 2 two-dimensional material, wherein the volatilization temperature of the Mo oxide source is, for example, 780 - 820 °C. The volatilization temperature of the sulfur source is 140 - 160 °C. The deposition time can be, for example, 15 - 25 min.

[0040] The hetero-bonding method of the present invention includes two typical implementation manners, for example, including a one-step deposition manner (Manner A) and a two-stage deposition manner of nucleation - deposition (Scheme B).

[0041] The steps of the one-step deposition manner described in Scheme A are, for example: heating Zone 1 under a reverse gas flow, and then performing vapor deposition under a low-flow forward carrier gas flow of 50 - 200 sccm to obtain a small-sized Sb 2 O 3 / MX 2 heterojunction.

[0042] Preferably, the flow rate of the forward carrier gas stream can further be 70 to 85 sccm.

[0043] In Solution A of the present invention, the flow rate of the reverse carrier gas stream is 50 to 150 sccm, preferably 70 to 85 sccm.

[0044] In Solution A of the present invention, the temperature of Temperature 1 is preferably 440 to 460 °C.

[0045] In the present invention, the temperature of Temperature Zone 2 can be adjusted according to the position of the substrate and Temperature Zone 1, and specifically can be 200 to 400 °C; further 280 to 350 °C.

[0046] In the present invention, the time for single-step deposition is 1 to 8 min, preferably 2 to 5 min.

[0047] Another typical solution (Solution B) of the present invention: The PVD deposition method is a nucleation-deposition multi-step deposition method assisted by countercurrent in the inner tube, and its steps are as follows: First, place the Sb 2 O 3 source in the inner tube arranged along the axial direction of the gas-phase deposition tube in Temperature Zone 1, then heat Temperature Zone 1 to temperature T1 under reverse gas flow, then switch to forward gas flow for nucleation treatment, then switch to reverse gas flow to continue heating Temperature Zone 1 to temperature T2, and then switch to forward gas flow again for deposition treatment to obtain a large-area single-crystal Sb 2 O 3 / MX 2 heterojunction;

[0048] The temperature 400 °C ≤ T1 < T2 ≤ 480 °C;

[0049] The flow rate of the forward gas flow is 200 to 900 sccm.

[0050] Based on the inner-tube-assisted multi-stage PVD of the present invention, further combined with the joint control of the carrier gas flow rate and the nucleation and deposition temperatures, unexpectedly, synergy can be achieved, and the Sb 2 O 3 crystal domains can grow along a single orientation direction and finally cover the entire MX 2 , solving the technical problem that large-area high-quality gate dielectrics and the lossless integration of two-dimensional semiconductor / two-dimensional gate dielectric van der Waals heterojunctions cannot be achieved. In this preferred manner, Sb 2 O 3The direct large-scale growth has universality. Moreover, high-performance transistor devices can be obtained. The present invention solves the problem that most of the current vertical heterojunctions rely on mechanical peeling and then stacking methods, and realizes the lossless integration of two-dimensional semiconductor / two-dimensional gate dielectric van der Waals heterojunctions.

[0051] In the present invention, the inner tube can be a cylindrical hollow straight tube. In the present invention, the diameter of the inner tube can be 0.2 to 0.4 times the inner diameter of the vapor deposition tube.

[0052] In the present invention, the inner tube includes more than 2, preferably 3 to 6, stacked in parallel; and Sb is provided in each inner tube. 2 O 3 source.

[0053] In the present invention, it is preferred to set a plurality of inner tubes parallel to the axial direction of the vapor deposition tube and stacked in the radial direction in temperature zone 1, and Sb is added to each inner tube. 2 O 3 source, and the setting position of Sb in each inner tube. 2 O 3 source is within temperature zone 1.

[0054] In the present invention, there is no special requirement for the length of the inner tube, but it does not extend to the substrate in temperature zone 2.

[0055] In the present invention, the Sb set in the inner tube. 2 O 3 source is Sb. 2 O 3 powder or flaky Sb. 2 O 3 ; preferably flaky Sb. 2 O 3 . The research of the present invention also shows that under the means of variable current multi-step deposition of the inner tube of the present invention, further combined with the joint control of parameters such as the morphology of the Sb. 2 O 3 , the nucleation temperature and the carrier gas flow rate, etc., can further strengthen the synergy of the preparation process, and can further control the highly unidirectional growth of Sb. 2 O 3 A monolayer, highly crystalline, large-area Sb that can cover the MX2 substrate can be obtained. 2 O 3 / MX 2 heterojunction.

[0056] The temperature T1 is 400 to 440 °C, preferably 425 to 435 °C; the time for nucleation treatment is 2 to 5 s;

[0057] Preferably, the temperature T2 is 450 to 470 °C.

[0058] Preferably, the time for the deposition treatment is 0.5 to 3 min, preferably 1 to 2 min;

[0059] Preferably, the flow rate of the forward gas flow in the nucleation and deposition stages is 300 to 650 sccm, and further can be 550 to 630 sccm.

[0060] Preferably, there is no particular requirement for the flow rate of the reverse flow in the nucleation and deposition heating stages, for example, it can be 50 to 900 sccm, and further can be 300 to 650 sccm.

[0061] In the present invention, in the nucleation and deposition stages, the temperature of the temperature zone 2 (MX 2 substrate) is 200 to 400 °C, and further can be 280 to 350 °C.

[0062] Preferably, the components of the forward and reverse gas flows are both protective gases, such as at least one of nitrogen and inert gases.

[0063] The present invention also provides an Sb 2 O 3 / MX 2 heterojunction prepared by the preparation method described above.

[0064] The preparation method of the present invention can endow the prepared material with special physical and chemical characteristics, and the material with the characteristics prepared by this preparation method can exhibit excellent performance.

[0065] The present invention also provides an application of the Sb 2 O 3 / MX 2 heterojunction prepared by the preparation method described above, which is used to prepare at least one of optical, electrical, and magnetic devices.

[0066] In the present invention, based on conventional means, the Sb 2 O 3 / MX 2 heterojunction described above can be used to prepare at least one of the required optical, electrical, and magnetic devices.

[0067] The present invention also provides a device, which includes the Sb 2 O 3 / MX 2 heterojunction prepared by the preparation method described above, or is prepared from the Sb 2 O 3 / MX 2 heterojunction.

[0068] Beneficial effects

[0069] (1): Through the current conversion technology, the present invention can regulate Sb 2 O 3 in the MX 2 van der Waals growth behavior, and can prepare Sb 2 O 3 / MoS 2 van der Waals heterojunction with high crystallinity and controllable thickness.

[0070] (2): By means of the inner tube-assisted current conversion multi-stage deposition described in the present invention, in cooperation with the combined coordination of parameters such as the carrier gas flow rate and temperature during the treatment process, various large-area single-crystal semiconductor / gate dielectric heterojunctions can be obtained for the first time in the industry. For example: Sb 2 O 3 / WSe 2 van der Waals heterojunction, Sb 2 O 3 / WS 2 van der Waals heterojunction, Sb 2 O 3 / MoS 2 van der Waals heterojunction, Sb 2 O 3 / MoSe 2 and other van der Waals heterojunctions can be integrated without damage.

[0071] The MX 2 nanosheets prepared by the present invention have a thickness of 0.7 - 3 nm and a size of 100 - 400 μm; Sb 2 O 3 nanosheets have a thickness of 0.7 - 6 nm and a size of 1 - 20 μm. The present invention is compatible with semiconductor processes and is easy to realize large-scale preparation and integration.

[0072] (3): During the preparation process of the present invention, there are no complex operation steps and the use of expensive raw materials. The equipment is simple, and the operation is simple and easy to perform with good reproducibility.

[0073] (4): The prepared materials have excellent properties. For example, Sb 2 O 3 / WSe 2 prepared by the present invention can be applied to electronic devices. The Sb 2 O 3 nanosheets improve the ability of the gate dielectric to form van der Waals contact with the semiconductor, improve the current density and on-off ratio, reduce the leakage current, and make the subthreshold swing close to the ideal subthreshold swing (60 mV / dec). It endows Sb 2 O 3 molecular crystals with the prospect of being used as dielectrics in 2D devices, which helps to promote the development of microelectronic device technology. Description of the Drawings

[0074] Figure 1 Prepare Sb for Example 1 2 O 3 / MX 2 Schematic diagram of chemical vapor deposition device for van der Waals heterojunction;

[0075] Figure 2 WSe single crystal optical photo prepared by bidirectional gas flow CVD method; 2

[0076] Figure 3 Sb for Example 1 2 O 3 / WSe 2 Van der Waals heterojunction optical photo;

[0077] Figure 4 Sb for Example 1 2 O 3 / MoS 2 Van der Waals heterojunction optical photo;

[0078] Figure 5 Sb with different thicknesses prepared for Example 1 2 O 3 / WSe 2 Atomic force microscope characterization of heterojunction;

[0079] Figure 6 Sb prepared for Comparative Example 1 2 O 3 / WSe 2 Van der Waals heterojunction optical photo;

[0080] Figure 7 Prepare large-area single crystal Sb for Example 2 2 O 3 / WSe 2 Schematic diagram of chemical vapor deposition device for van der Waals heterojunction;

[0081] Figure 8 Sb in nucleation stage prepared for Example 2 2 O 3 / WSe 2 Heterojunction;

[0082] Figure 9 Sb with single orientation after deposition at temperature T1 for t1 in Example 2 2 O 3 / WSe 2 Atomic force microscope photo of heterojunction;

[0083] Figure 10 Large-area single crystal Sb prepared after deposition at temperature T2 for t2 in Example 2 2 O​3 / WSe 2 Comparison of optical photos before and after the growth of van der Waals heterojunction;

[0084] Figure 11 Sb at the nucleation stage prepared in Comparative Example 2 2 O 3 / WSe 2 heterojunction;

[0085] Figure 12 Sb at the growth stage at low temperature prepared in Comparative Example 3 2 O 3 / WSe 2 Atomic force microscope photo of heterojunction;

[0086] Figure 13 Sb prepared in Comparative Example 4 2 O 3 / WSe 2 Optical photo of heterojunction;

[0087] Figure 14 Sb obtained in Comparative Example 5 2 O 3 / WSe 2 Atomic force microscope photo of heterojunction.

[0088] Figure 15 Sb obtained in Comparative Example 6 2 O 3 / WSe 2 Atomic force microscope photo of heterojunction.

[0089] Figure 16 Prepared in Example 2-ABCD, changing the number of inner tube stacks, changing the Sb powder state in the inner tube, the flow rate of the forward air flow, and the growth time at the growth stage to obtain Sb 2 O 3 powder state, the flow rate of the forward air flow, and the growth time at the growth stage to obtain Sb 2 O 3 / WSe 2 Optical photo of van der Waals heterojunction.

[0090] Figure 17 Sb prepared in Example 3 2 O 3 / WSe 2 Optical picture of the field effect transistor.

[0091] Figure 18 、 19 Sb prepared in Example 3 2 O 3 / WSe 2 Electrical transport and transfer characteristic curves obtained from the field effect transistor test.

[0092] Figure 20 Sb prepared for Example 3-1 2 O 3 / WSe 2 Optical picture of the inverter.

[0093] Figure 21 Sb prepared for Example 3-1 2 O 3 / WSe 2 Typical voltage transfer curve obtained for the inverter. Detailed implementation manners

[0094] The present invention will be further described below through examples, but the content of the present invention is not limited to the following content only.

[0095] The Sb 2 O 3 / MX 2 Preparation method of the heterojunction, which includes the following steps:

[0096] Step (1): Obtain a two-dimensional material of a semiconductor transition metal chalcogenide s-TMD substrate on a substrate, and the chemical formula of the two-dimensional material of the s-TMD substrate is MX 2 ; M is W or Mo; X is S or Se;

[0097] Step (2): Perform physical vapor deposition on the two-dimensional material of the s-TMD substrate obtained in step (1) using Sb 2 O 3 as the evaporation source to obtain an Sb 2 O 3 / MX 2 heterojunction.

[0098] In the present invention, the existing method can be adopted to form the MX 2 substrate two-dimensional material on the substrate.

[0099] The present invention discovers through research that innovatively adopting the physical vapor deposition means with variable carrier gas flow helps to obtain large-size and high-crystallinity MX 2 substrate two-dimensional materials, which helps subsequent deposition to obtain single-crystalline state and good-morphology MX 2 semiconductor materials and Sb 2 O 3 / MX 2 heterojunction.

[0100] The physical vapor deposition means with variable carrier gas flow is, for example: heating MX 2 to the volatilization temperature under a reverse carrier gas flow, and then changing the carrier gas to a forward gas flow to deposit MX 2Deposited on a substrate to obtain the two-dimensional material of the semiconductor substrate; the reverse direction refers to the direction from the substrate to MX 2 ; the forward direction refers to the direction from MX 2 to the substrate; or obtained by chemical vapor deposition of an X elemental source and a compound of M metal.

[0101] By using this preferred method, two-dimensional materials of the substrate with high crystallinity and large area can be obtained. Taking WSe 2 single crystal as an example, if a unidirectional gas flow (forward gas flow) is directly used, the size of the obtained WSe 2 single crystal is small, generally below 100 μm, and the surface is uneven.

[0102] In the present invention, for different MX 2 , in combination with the means of carrier gas variable flow physical vapor deposition, further controlling the volatilization temperature and the deposition temperature helps to further improve the size of the two-dimensional material of the substrate, helps to obtain micron-sized and high-quality single crystal materials, and thus helps to further facilitate the subsequent growth and preparation of Sb 2 O 3 / MX 2 heterojunction.

[0103] Preferably, the volatilization temperature of the MX 2 is 1160-1200 °C; the deposition temperature is 840-900 °C.

[0104] The MX 2 is WSe 2 , and its volatilization temperature is 1165-1185 °C; further preferably 1170-1180 °C; the deposition temperature is 840-850 °C; further preferably 845-850 °C.

[0105] Alternatively, the MX 2 is WS 2 , and its volatilization temperature is 1180-1200 °C; the deposition temperature is 850-860 °C.

[0106] Alternatively, MX 2 is MoS 2 , and its volatilization temperature is 1195-1200 °C; the deposition temperature is 860-865 °C.

[0107] Alternatively, MX 2 is MoSe 2 , and its volatilization temperature is 1195-1200 °C; the deposition temperature is 860-865 °C.

[0108] The carrier gas is a protective gas, and the protective gas is, for example, nitrogen or an inert gas, preferably Ar.

[0109] In the present invention, the MX can also be synthesized by a conventional CVD method. 2 . For example, MoO3 and sulfur can be subjected to CVD deposition to obtain molybdenum sulfide. Among them, the volatilization of Mo oxide and the temperature of CVD deposition are 750 - 850 °C. The volatilization temperature of sulfur can be 120 - 180 °C.

[0110] Preferably, the flow rates of the forward and reverse carrier gases are both 70 - 85 sccm;

[0111] Preferably, in step (1), the deposition time is 1 - 8 min, further preferably 2 - 5 min.

[0112] Preferably, the prepared MX 2 substrate two-dimensional material is a single-layer or double-layer single-crystal nanosheet with a size of 100 - 300 μm.

[0113] The present invention studies and finds that the carrier gas variable flow physical vapor deposition method can also be used for the growth of Sb 2 O 3 . By further controlling the volatilization temperature and the growth time, high-quality Sb 2 O 3 nanosheets are obtained.

[0114] An implementable mode A of the present invention specifically lies in:

[0115] Place the Sb 2 O 3 source in boat A and place it in zone 1. Place the MX 2 substrate in boat B; preheat zone 1 under a reverse carrier gas. When the temperature reaches the required volatilization temperature, change the gas flow to forward and perform deposition treatment. In this mode, the flow rate of the forward gas can be 50 - 200 sccm, further preferably 75 - 85 sccm. Among them, the carrier gas can be a protective atmosphere, such as nitrogen or an inert gas. There is no special requirement for the flow rate of the countercurrent gas, and it can also be 70 - 85 sccm, further preferably 75 - 85 sccm. The deposition time is 1 - 8 min, preferably 2 - 5 min. The evaporation temperature of the Sb 2 O 3 source (the temperature of zone 1) is 400 - 460 °C, further preferably 410 - 460 °C. The temperature of zone 2 can be, for example, 200 - 400 °C; further 280 - 350 °C.

[0116] The so-called reverse direction refers to the direction from the MX 2 substrate to the Sb 2 O 3 source; the forward direction refers to the direction from the Sb 2 O 3 source to the MX 2The direction of the base.

[0117] In the present invention, Sb is reacted with a reverse carrier gas flow. 2 O 3 Heated to the volatilization temperature (nucleation temperature), then changed the carrier gas to a positive gas flow, at the deposition temperature Sb 2 O 3 Deposited in MX 2 On the substrate, the Sb 2 O 3 / MX 2 Heterojunction materials.

[0118] The present invention also shows that it is difficult to control Sb by directly increasing the carrier flow rate or regulating the temperature. 2 O 3 Directed growth makes it difficult to obtain an ideal large-sized heterojunction. To address the problems faced in preparing large-sized heterojunctions, the present invention adopts an inner tube variable flow multi-step auxiliary synthesis scheme (Scheme B): specifically:

[0119] In the temperature zone 1, one or more inner tubes parallel to the axial direction of the vapor deposition tube are arranged (when there are multiple inner tubes, each inner tube is stacked in the temperature zone 1), and Sb 2 O 3 It is arranged in the inner tube, and then the temperature zone 1 is heated to temperature T1 (the temperature in the nucleation stage is 400-440°C, and more preferably 425-435°C) under reverse airflow, and then the airflow is changed to forward, and nucleation treatment is carried out. After nucleation insulation, it is switched to reverse airflow, and temperature 1 is further heated to temperature T2 (450-470°C), and then switched to forward airflow for insulation deposition treatment. In this method, the flow rate of the forward airflow is 200-900sccm; the reverse airflow can be 50-900sccm, wherein the carrier gas can be a protective atmosphere, such as nitrogen or an inert gas. The nucleation time is 2-5s, and the deposition time is 0.5-3min. In the nucleation and deposition stages, the distance between temperature zones 1 and 2 remains unchanged, wherein the temperature of temperature 2 in the nucleation and deposition stages is 200-400°C; further 280-350°C. Among them, the temperature of temperature 2 in the deposition stage is not much different from the temperature of temperature 2 in the nucleation stage, which is within 10°C.

[0120] Scheme B of the present invention realizes Sb 2 O 3 The crystal domain grows along a single orientation direction and eventually covers the entire MX 2 , which solves the technical problem of being unable to achieve lossless integration of large-area high-quality gate dielectrics and two-dimensional semiconductor / two-dimensional gate dielectric van der Waals heterojunctions. The technical solution of the present invention can achieve Sb on different semiconductor materials. 2 O 3The direct growth of nanostructured carbon nanotubes is universal and can also produce high-performance transistor devices.

[0121] The present invention also provides a large Sb prepared by the preparation method. 2 O 3 / MX 2 Heterojunction.

[0122] MX 2 The thickness is 0.7-3nm and the size is 100-400μm; Sb 2 O 3 The thickness is 0.7 to 6 nm and the size is 1 to 20 μm;

[0123] Preferably, the large-area single crystal Sb 2 O 3 The van der Waals dielectric material method has a certain universality and can be applied to the growth of other semiconductor substrates, including Sb 2 O 3 / WSe 2 Van der Waals heterojunction, Sb 2 O 3 / WS 2 Van der Waals heterojunction, Sb 2 O 3 / MoS 2 Van der Waals heterojunction, Sb 2 O 3 / MoSe 2 The van der Waals heterojunction is compatible with semiconductor technology and can be easily prepared and integrated on a large scale.

[0124] The present invention also provides a Sb 2 O 3 / MX 2 Applications of heterojunctions, preparation of electronic devices using them;

[0125] Preferably, it is manufactured as a field effect transistor.

[0126] As a preferred step, the steps are: after depositing Sb 2 O 3 / MX 2 Van der Waals heterojunction SiO 2 A layer of polymethyl methacrylate (PMMA) was spin-coated on the surface of Si / Si, and the sample was marked by electron beam exposure. The excess antimony oxide was then etched with hydrochloric acid and metal was deposited on the surface. Finally, the gold film and PMMA were removed to obtain a field effect transistor, and the device was annealed at 200℃ for 2h.

[0127] Preferably, the vacuum coating machine is used to coat Sb 2 O 3 / MX2 Depositing metal on the surface of the van der Waals heterojunction;

[0128] Preferably, the metal is Au, and its thickness is 40 - 60 nm;

[0129] Preferably, it is applied to the preparation of electronic devices;

[0130] The electronic device is a field - effect transistor, including a channel MX 2 and a dielectric layer Sb 2 O 3 and source - drain electrodes Au;

[0131] The present invention utilizes Figure 1 the tube furnace shown for CVD deposition. Place the porcelain boat containing Sb 2 O 3 in the constant - temperature zone 1 of the tube furnace, and place the WSe 2 / SiO 2 / Si as the growth substrate on another porcelain boat and place it in the downstream variable - temperature zone of the tube furnace to obtain an appropriate crystal growth temperature.

[0132] The process of the present invention has no special requirements for the substrate, and it is also unexpectedly suitable for the deposition of Sb 2 on the surface of the MX 2 two - dimensional material, and then an Sb 3 O 2 O 3 / WSe 2 heterojunction can be formed. The MX 2 two - dimensional material is prepared by conventional CVD and PVD methods.

[0133] In the following cases, the MX 2 two - dimensional materials used are all prepared by the following typical preparation methods.

[0134] For example: the preparation conditions of the WSe 2 two - dimensional material (also known as the WSe 2 / SiO 2 / Si substrate): Place the porcelain boat containing WSe 2 in the constant - temperature zone 1 (the central temperature zone, upstream) of the tube furnace, and place a 285 - nm SiO 2The SiO₂ / Si substrate is placed on another porcelain boat and positioned downstream in a tube furnace to obtain an appropriate crystal growth temperature. Before heating, the air in the quartz tube is purged with a large flow rate of argon gas. Then, the temperature of the constant temperature zone 1 is raised to 1180 °C, and the argon gas flow rate is 80 sccm. During the source temperature increase process, a reverse gas flow (from the substrate to the source) is adopted. After the temperature increase is completed, the gas flow is changed to a forward flow (from the source to the substrate). The temperature of the zone where the substrate is located is 845 - 850 °C, and it is kept at this temperature for three minutes for growth. On the SiO₂ / Si substrate, single crystal WSe₂ nanosheets will be formed. After the growth is completed, the WSe₂ substrate is quickly pulled out, and the gas flow direction is changed to reverse. The optical photograph of the prepared WSe₂ nanosheets is as shown. 2 / Si substrate, there will be single crystal WSe₂ 2 nanosheets generated. After the growth is completed, quickly pull out the WSe₂ 2 substrate and change the gas flow direction to reverse. The prepared WSe₂ 2 nanosheets are as shown in Figure 2 the figure.

[0135] MoS₂ 2 two-dimensional material (also known as MoS₂ 2 / SiO₂ 2 / Si substrate) preparation conditions: Place 2 mg of molybdenum trioxide and 30 mg of sulfur powder in two different porcelain boats respectively. Place a SiO₂ / Si substrate with its bright side facing down flat on the porcelain boat loaded with molybdenum trioxide. Place the porcelain boat loaded with sulfur powder in the upstream temperature zone and the porcelain boat with molybdenum trioxide in the downstream temperature zone. The carrier gas flow is a constant 60 sccm of argon gas. Within 20 minutes, heat the upstream and downstream temperature zones to 800 °C and 150 °C respectively, and keep at a constant temperature for five minutes. At the end of the growth period, wait for the tube furnace to cool naturally to room temperature. 2

[0136]

[0136] WS₂ 2 two-dimensional material (also known as WS₂ 2 / SiO₂ 2 / Si substrate) preparation method: Use a single-temperature zone tube furnace. Place the porcelain boat loaded with WS₂ powder at the center of the temperature zone of the tube furnace. Place a SiO₂ / Si substrate with its bright side facing up flat on the porcelain boat, which is located downstream in the tube furnace. With 80 sccm of argon gas flowing in the reverse direction, heat the temperature at the center of the tube furnace temperature zone to 1185 °C (source evaporation temperature). After reaching 1185 °C, change the flow direction of the 80 sccm carrier gas to forward. The temperature of the zone where the substrate is located is 855 ± 5 °C, and keep it at a constant temperature for 2 minutes. After the growth process is completed, change the argon gas direction to reverse again and let the furnace cool naturally to the ambient temperature. 2 2 2

[0137] I. Examples of Scheme A

[0138] Example 1

[0139] Sb₂O₃ / WSe₂ 2 O₃ 3 / WSe₂2 Preparation of heterojunction:

[0140] Sb 2 O 3 / WSe 2 The experimental setup diagram of the heterojunction is as Figure 1 shown.

[0141] First, high-quality and large-sized single-crystal WSe 2 nanosheets are synthesized by the bidirectional gas flow method, Figure 2 and bilayer single-crystal WSe 2 is obtained.

[0142] Place the magnetic boat containing Sb 2 O 3 powder at the constant temperature zone 1 upstream of the tube furnace, and place the WSe 2 / SiO 2 / Si substrate (or MoS 2 / SiO 2 / Si) in the variable temperature zone downstream of the tube furnace (temperature zone 2, the distance between the magnetic boats in temperature zone 1 and temperature zone 2 is 10 - 12 cm). Before heating, use argon gas with a large flow rate to exhaust the air in the quartz tube. Then, heat the constant temperature zone 1 to 450 °C under a reverse argon gas flow of 80 sccm (in the direction from temperature zone 2 to temperature zone 1), and the temperature of temperature zone 2 is 300 ± 5 °C; subsequently, switch the carrier gas to a forward Ar gas flow of 80 sccm (from the source to the substrate (temperature zone 2)), keep the temperature for growth for three minutes, and Sb 2 / SiO 2 nanosheets will be generated on the / Si substrate. After the growth is completed, quickly pull out the Sb 2 O 3 / WSe 2 O 3 / WSe 2 heterojunction substrate, change the gas flow direction to reverse, and take out the prepared heterojunction after cooling.

[0143] Figure 3 The optical photo of the prepared Sb 2 O 3 / WSe 2 heterojunction. The light red part is the substrate, and the light purple triangles represent Sb 2 O 3 nanosheets with uniform thickness.

[0144] Figure 4 The optical photo of the prepared Sb 2 O 3 / MoS 2 heterojunction. The light red part is the substrate, and the light purple triangles represent Sb 2O 3 nanosheet

[0145] Figure 5 For the prepared Sb with different thicknesses 2 O 3 / WSe 2 atomic force diagram of the heterojunction, the triangles represent Sb nanosheets with uniform thickness 2 O 3 nanosheet

[0146] Comparative Example 1

[0147] Compared with Example 1, the difference is only that in Step 1, the Sb 2 O 3 / WSe 2 heterojunction is not synthesized by the variable gas flow method, but by the traditional unidirectional gas flow method (both the volatilization and deposition processes are carried out under the forward gas flow). Other operations and parameters are the same as those in Example 1, and the obtained Sb 2 O 3 has a thicker and non-uniform thickness

[0148] Figure 6 is the Sb 2 O 3 / WSe 2 heterojunction synthesized by the unidirectional gas flow method

[0149] II. Examples of Scheme B

[0150] Example 2

[0151] Use the tubular furnace shown in Figure 7 for deposition. The deposition tube (outer diameter 2.5 cm, length 1 m) of the tubular furnace includes a constant temperature zone 1 (zone 1) at the upstream and a variable temperature zone 4 at the downstream; five axially parallel stacked inner tubes (2) are provided in the zone 1. Each inner tube is a cylindrical hollow straight tube with an outer diameter of 8 mm and a length of 40 mm, and its axial direction is parallel to the axial direction of the deposition tube. The outer diameter of the inner tube is 0.3 times the inner diameter of the deposition tube; each inner tube does not extend into the zone 4 Figure 7

[0152] Sbsheets (3) are arranged in each inner tube of the zone 1, and WSe 2 O 3 / SiO 2 / Si(5) is arranged in the variable temperature zone 4; the distance between the Sb 2 sheets in the zone 1 and WSe 2 O 3 / SiO 2 / Si is 11 - 12 cm; 2

[0153] ​Preheat Zone 1 to T1 (430 °C) within 20 min under a reverse gas flow (8) of 600 sccm, with the temperature of Variable Temperature Zone 4 being 290 ± 5 °C. Subsequently, switch to a forward gas flow 7 (Ar atmosphere with a flow rate of 600 sccm), and hold for 3 s (marked as t1) for nucleation treatment; then switch back to the reverse gas flow 8, heat the temperature of Zone 1 to T2 (460 °C) within 1 min, switch to the forward gas flow 7 again, hold for deposition for 2 min (marked as t2), and then switch to the reverse gas flow 8 for cooling treatment to obtain large-area Sb. 2 O 3 / WSe 2 heterojunction.

[0154] Figure 8 is Sb at the nucleation stage (after deposition at temperature T1 for t1). 2 O 3 / WSe 2 heterojunction.

[0155] Figure 9 is Sb after deposition at temperature T1 for t1. 2 O 3 / WSe 2 atomic force microscope image of the SbO / WSe heterojunction.

[0156] Figure 10 is large-area single-crystal Sb after deposition at temperature T2 for t2. 2 O 3 / WSe 2 Comparison of optical images of the van der Waals heterojunction before and after growth.

[0157] Comparative Example 2

[0158] Compared with Example 2, the only difference is that the flow rate of the forward gas flow 7 during the temperature holding and deposition stages at temperatures T1 and T2 is controlled at 80 sccm.

[0159] Figure 11 is Sb at the nucleation stage under normal gas flow. 2 O 3 / WSe 2 atomic force microscope image of the SbO / WSe heterojunction. The Sb obtained under these conditions 2 O 3 has a small nucleation density, uneven thickness, and is prone to polycrystal formation.

[0160] Comparative Example 3

[0161] Compared with Example 2, the only difference is that the temperature of T2 is the same as that of T1, that is, the temperature of T2 is controlled to be the same as that of T1, both being 430 °C, and other operations and parameters are the same as those in Example 2.

[0162] Figure 12Sb of Comparative Example 3 2 O 3 / WSe 2 Atomic force microscopy image of the heterojunction. The Sb 2 O 3 crystallite domains do not have a single orientation.

[0163] Comparative Example 4

[0164] Compared with Example 2, the only difference is that the inner tube in Temperature 1 is removed, and the Sb 2 O 3 flakes are placed in a magnetic boat, and other operations and parameters are the same as those in Example 2.

[0165] Figure 13 This is the Sb 2 O 3 grown with the Sb 2 O 3 / WSe 2 heterojunction optical image. The material obtained under this condition has uneven thickness and does not completely cover the WSe 2 substrate.

[0166] Comparative Example 5

[0167] Compared with Example 2, the only difference is that the process of Temperature T1 is cancelled, and the temperature zone 1 is directly heated to 460 °C under the reverse gas flow 8 in advance, and then deposited for 2 min under the forward gas flow 7. Other operations and parameters are the same as those in Example 2.

[0168] Figure 14 This is the Sb 2 O 3 / WSe 2 atomic force microscopy image of the heterojunction. The material obtained under this condition has a relatively low nucleation density and does not completely join together to form a film.

[0169] Comparative Example 6

[0170] Compared with Example 2, the only difference is that the heating stage is carried out under the forward gas flow.

[0171] Figure 15 This is the Sb 2 O 3 / WSe 2 atomic force microscopy image of the heterojunction. The material obtained under this condition will randomly show individual relatively thick Sb 2 O 3 triangular crystallite domains with uneven thickness distribution.

[0172] Example 2-A

[0173] Compared with Example 2, the only difference is that the number of inner tube stacks is changed. The experimental groups are as follows:

[0174] Group A: 1 inner tube;

[0175] Group B: 2 inner tubes;

[0176] All other operations and parameters are the same as in Example 2.

[0177] Figure 16 A is the Sb 2 O 3 / WSe 2 heterojunction. When the coverage is not complete enough and the concentration distribution is uneven, Sb 2 O 3 is more likely to grow vertically into a thicker material (the thickness of purple-red, purple, and blue increases in turn). The preparation results of A and B are similar, and Figure 16A is a diagram of a case in Group B.

[0178] Example 2 - B

[0179] Compared with Example 2, the only difference is that the Sb 2 O 3 sheets in the inner tube are changed to Sb 2 O 3 powder. All other operations and parameters are the same as in Example 2.

[0180] Figure 16 B is the Sb 2 O 3 / WSe 2 heterojunction Sb 2 O 3 has uneven thickness and is inferior to Example 2.

[0181] Example 2 - C

[0182] Compared with Example 2, the only difference is that the flow rate of the forward airflow is changed, which are:

[0183] Group A: The flow rate of the forward airflow is 200 Sccm;

[0184] Group B: The flow rate of the forward airflow is 300 Sccm;

[0185] All other operations and parameters are the same as in Example 2.

[0186] Figure 16 C is the Sb 2 O 3 / WSe 2 heterojunction. When the forward flow rate is small, the nucleation density is also small, and Sb 2 O 3It is difficult to form a film by splicing. The preparation results of A and B are similar, and Figure 16C is a diagram of a case in Group B.

[0187] Example 2-D

[0188] Compared with Example 2, the only difference is that the growth time in the growth stage is changed, which are respectively:

[0189] Group A: The temperature T1 is 430 °C, and the temperature T2 is 450 °C; each treatment time is 3 s, 0.5 min

[0190] Group B: The temperature T1 is 430 °C and the temperature T2 is 450 °C; each treatment time is 3 s, 1 min;

[0191] Other operations and parameters are the same as those in Example 2.

[0192] Figure 16 D is the Sb prepared under this condition 2 O 3 / WSe 2 heterojunction. When the time is short, the Sb 2 O 3 coverage rate is low. The preparation results of A and B are similar, and Figure 16D is a diagram of a case in Group B.

[0193] III. Device preparation

[0194] Example 3

[0195] Sb 2 O 3 / WSe 2 Preparation method of a field effect transistor. Spin-coat a layer of polymethyl methacrylate (PMMA) on the Sb 2 O 3 / WSe 2 heterojunction (the material prepared in Example 1), then mark the sample by electron beam exposure, and etch the excess Sb with hydrochloric acid 2 O 3 After that, deposit 50 nm of Au on its surface, then anneal the device at 200 °C for 2 h, and finally remove the gold film and PMMA with acetone to obtain Sb with different thicknesses 2 O 3 / WSe 2 field effect transistor.

[0196] Sb 2 O 3 / WSe 2 The optical picture of the Sb Figure 17 field effect transistor is as shown, where S, TG, and D represent the source metal, top gate metal, and drain metal respectively.

[0197] Figure 17 In it, SiO2 The / Si substrate is gray, and Sb 2 O 3 is blue, and WSe 2 is purple. The golden long rectangle on the surface is the deposited metal Au.

[0198] The electrical transport and transfer characteristic curves obtained by testing are respectively as Figure 18 and Figure 19 shown. The on / off ratio of 10 8 , 10 -12 -10 -13 μA / μm 2 of low gate leakage current and a subthreshold swing of 60 mV / dec show excellent gate tunability.

[0199] Example 3-A

[0200] According to the method of Example 3, the heterojunction prepared in Example 2 was made into a device. The steps are as follows:

[0201] Sb 2 O 3 / WSe 2 The preparation method of the inverter was to spin-coat a layer of polymethyl methacrylate (PMMA) on the Sb 2 O 3 / WSe 2 heterojunction (the material prepared in Example 2) obtained by CVD method, then mark the sample by electron beam lithography, etch the excess Sb 2 O 3 with hydrochloric acid, deposit 50 nm Au on its surface, then anneal the device at 200 °C for 2 h, and finally remove the gold film and PMMA with acetone to obtain the Sb 2 O 3 / WSe 2 inverter with different thicknesses.

[0202] The optical picture of the Sb 2 O 3 / WSe 2 inverter is as Figure 20 shown, where GND V dd V out V in represent ground, power supply voltage, output voltage, and input voltage respectively.

[0203] Figure 20 In, the SiO 2 / Si substrate is gray, and Sb 2 O 3 / WSe 2 is dark purple, and the golden long rectangle on the surface is the deposited metal Au.

[0204] Typical voltage transfer curves obtained by testing are respectively as follows Figure 21 , showing a gain of 1.5 when the operating voltage V dd = 1V.

Claims

1. A method for preparing a Sb2O3 / MX2 heterojunction, characterized in that: The Sb2O3 source is arranged in the temperature zone 1 of the vapor deposition tube, and the MX2 two-dimensional material substrate is arranged in the temperature zone 2 of the vapor deposition tube; The temperature of the temperature zone 1 is raised to 400-480° C. in advance under a reverse carrier gas flow; the carrier gas flow is then changed to a forward direction, so that the volatilized Sb2O3 is PVD deposited on the MX2 two-dimensional material substrate to obtain the Sb2O3 / MX2 heterojunction; The reverse direction refers to the direction from temperature zone 2 to temperature zone 1, and the forward direction refers to the direction from temperature zone 1 to temperature zone 2; In the MX2 two-dimensional material, the M is a transition metal; and the X is S or Se.

2. The method for preparing a Sb2O3 / MX2 heterojunction according to claim 1, characterized in that: In the MX2 two-dimensional material, the M is W or Mo; The MX2 two-dimensional material is synthesized by PVD or CVD method; Preferably, the steps of PVD synthesis of MX2 two-dimensional material are: heating MX2 to a volatilization temperature under a reverse carrier gas flow, then changing the carrier gas to a forward gas flow, and depositing MX2 on a substrate at a deposition temperature to obtain the s-TMD substrate two-dimensional material; the reverse direction refers to the direction from the substrate to MX2; the forward direction refers to the direction from MX2 to the substrate; Preferably, the volatilization temperature of MX2 is 1160-1200°C; the deposition temperature is 840-900°C; Preferably, the MX2 is WSe2, whose volatilization temperature is 1165-1185°C; and the deposition temperature is 840-850°C; Alternatively, the MX2 is WS2, whose volatilization temperature is 1180-1200°C; and whose deposition temperature is 850-860°C; Alternatively, MX2 is MoS2, whose volatilization temperature is 1195-1200°C; and whose deposition temperature is 860-865°C; Alternatively, MX2 is MoSe2, whose volatilization temperature is 1195-1200°C; and the deposition temperature is 860-865°C; The carrier gas is protective gas, and the flow rates of the forward and reverse carrier gases are both 70-85 sccm; The deposition time is 1 to 8 minutes, and further 2 to 5 minutes.

3. The method for preparing a Sb2O3 / MX2 heterojunction according to claim 1, characterized in that: The PVD deposition method is a single-step deposition method, and its steps are: The temperature of temperature zone 1 is increased under a reverse gas flow, and then vapor deposition is performed under a low flow rate of 50 to 200 sccm of a forward carrier gas flow to obtain a small-sized Sb2O3 / MX2 heterojunction; Preferably, the forward carrier gas flow is 70 to 85 sccm; Preferably, the flow rate of the reverse carrier gas flow is 50 to 150 sccm, preferably 70 to 85 sccm; Preferably, the temperature of the temperature 1 is preferably 440-460°C; Preferably, the temperature of temperature zone 2 is 200-400°C; further 280-350°C; Preferably, the single-step deposition time is 1 to 8 minutes, preferably 2 to 5 minutes.

4. The method for preparing a Sb2O3 / MX2 heterojunction according to claim 1, characterized in that: The PVD deposition method is a nucleation-deposition multi-step deposition method assisted by an inner tube countercurrent, and the steps are as follows: pre-placing the Sb2O3 source in an inner tube arranged along the axial direction of the vapor deposition tube in the temperature zone 1, then heating the temperature zone 1 to a temperature T1 under a reverse airflow, then switching to a forward airflow for nucleation treatment, then switching to a reverse airflow to continue heating the temperature zone 1 to a temperature T2, then switching to a forward airflow again for deposition treatment, and obtaining a large-area single crystal Sb2O3 / MX2 heterojunction; Temperature 400℃≤T1 <T2≤480℃; The flow rate of the forward gas flow is between 200 and 900 sccm.

5. The method for preparing a Sb2O3 / MX2 heterojunction according to claim 4, characterized in that: The inner tubes include more than 2, preferably 3 to 6, stacked in parallel; and each inner tube is provided with a Sb2O3 source.

6. The method for preparing a Sb2O3 / MX2 heterojunction according to claim 4 or 5, characterized in that: The Sb2O3 source disposed in the inner tube is Sb2O3 powder or flake Sb2O3.

7. The method for preparing a Sb2O3 / MX2 heterojunction according to any one of claims 4 to 6, characterized in that: The temperature T1 is 400-440°C, preferably 425-435°C; the nucleation treatment time is 2-5s; Preferably, the temperature T2 is 450-470°C; Preferably, the deposition treatment time is 0.5 to 3 minutes, preferably 1 to 2 minutes; Preferably, the flow rate of the forward gas flow during the nucleation and deposition stages is 300 to 650 sccm; Preferably, the reverse flow rate is 50 to 900 sccm; Preferably, during the nucleation and deposition stages, the temperature of temperature zone 2 is 200-400°C; Preferably, the components of the forward and reverse airflows are both protective gases.

8. A Sb2O3 / MX2 heterojunction prepared by the preparation method according to any one of claims 1 to 7.

9. An application of a Sb2O3 / MX2 heterojunction prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The device is prepared into at least one of optical, electrical and magnetic devices.

10. A device, characterized in that: The invention relates to a Sb2O3 / MX2 heterojunction prepared by the preparation method according to any one of claims 1 to 7, or prepared by the Sb2O3 / MX2 heterojunction.

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