A method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure

Abstract

The application discloses a preparation method of a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure. The method is chemical vapor deposition, and Si / SiO2 is used as a substrate, a metal rhenium foil (Re) is used as a rhenium source, and a metal molybdenum foil (Mo) is used as a molybdenum source. The metal rhenium foil is laid on one end surface of the metal molybdenum foil, the substrate is inverted on the metal molybdenum foil, and the substrate is reacted with sulfur vapor to prepare a two-dimensional ReS2 / MoS2 vertical heterostructure with a multilayer ReS2 as a bottom layer and a double-layer MoS2 as a top layer. The obtained two-dimensional ReS2 / MoS2 vertical heterojunction material is a crystal stacked by two crystals with different sizes, presents obvious luminescent properties, can be used as a channel material of a transistor and applied to the field of ultrathin electronic devices, and has potential application in the field of high-efficiency light detectors.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material preparation, and particularly relates to a preparation method of a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure. BACKGROUND

[0002] Ultra-thin two-dimensional semiconductor materials, such as transition metal dichalcogenides (TMDs), black phosphorus, boron nitride (BN), etc., have excellent optical and electrical properties, thus making them have considerable application prospects in the fields of field effect transistors, optical detectors, light-emitting diodes, energy, etc. Compared with bulk materials, thin-layer two-dimensional transition metal dichalcogenides (TMDs) represented by molybdenum disulfide (MoS2) have very excellent optical and electrical properties, such as layer-number-related indirect-direct band gap transition, adjustable band width, high light emission efficiency, rich excitons, and good flexibility. However, it is difficult to realize the regulation of interlayer excitons and the control of charge transfer of a single two-dimensional TMD material, thus greatly limiting its application in the field of high-performance, low-energy consumption ultra-thin optoelectronic devices. In order to further study the intrinsic optical and electrical properties of the material and expand its application field, researchers have focused on two-dimensional TMD-based vertical heterostructures.

[0003] Two-dimensional TMD-based vertical heterostructures are usually stacked based on interlayer van der Waals force by two or more two-dimensional materials. Since there is no dangling bond on the surface of TMD two-dimensional material, the problem of lattice mismatch does not need to be considered in the preparation process of the TMD-based vertical heterostructure, thus making the construction of TMD vertical heterojunction and the research on its performance become one of the most popular directions of two-dimensional materials at present. Two-dimensional TMD vertical heterojunction usually presents many novel phenomena, such as high light absorption, adjustable interlayer exciton, and ultrafast and efficient charge transfer, thus making the van der Waals vertical heterostructure have great application potential in the field of next-generation high-performance, low-power-consumption optoelectronic devices.

[0004] So far, research work has mainly focused on the mechanical exfoliation of stacked vertical heterostructures, and the construction of different vertical heterostructures by multi-step (two-step or three-step) chemical vapor deposition, such as MoS2 / WSe2, WSe2 / MoSe2, MoS2 / WS2, WS2 / MoSe2 and ReS2 / MoS2, and the novel phenomena of their optical and electrical properties have been explored. So far, the reported two-dimensional ReS2 / MoS2 vertical heterostructure is prepared by the strategy of mechanical exfoliation + transfer or chemical vapor deposition + transfer, and the migration of electrons and holes is observed, and the energy band arrangement of the heterostructure is confirmed to be I-type structure based on the analysis of optical and electrical properties.

[0005] However, there is no report on the preparation of a two-dimensional rhenium sulfide / molybdenum sulfide vertical heterostructure by one-step chemical vapor deposition, in which rhenium sulfide is used as a bottom layer and molybdenum sulfide is used as a top layer. Therefore, a simple and feasible method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure needs to be developed, and the exciton luminescence characteristics thereof need to be studied, so as to meet the application thereof in the field of high-efficiency, low-power consumption and ultra-thin optoelectronic devices. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure, which realizes the preparation of a rhenium sulfide / molybdenum sulfide vertical heterostructure with two-dimensional rhenium sulfide as a bottom layer and two-dimensional molybdenum sulfide as a top layer by one-step chemical vapor deposition. The method is simple, low in cost, free of catalyst and friendly to the environment.

[0007] The technical solution adopted by the present application to solve the technical problem is: a preparation method of a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure, comprising the following steps:

[0008] S1, using Si / SiO2 as a substrate, metal rhenium foil as a rhenium source, metal molybdenum foil as a molybdenum source, and sulfur powder as a sulfur source;

[0009] S2, a double-temperature-zone horizontal tube furnace is set as a sulfur source temperature zone and a deposition temperature zone in sequence according to the airflow direction, two quartz boats are placed in the same quartz tube, and the quartz tube is placed in the tube furnace, one of the quartz boats is placed with the sulfur source in the sulfur source temperature zone, and the other is placed with the rhenium source, the molybdenum source and the growth substrate, the oxidized metal rhenium foil is laid flat on the surface of one end of the oxidized metal molybdenum foil, the end is close to the sulfur source temperature zone, the substrate is inverted and placed directly above the metal molybdenum foil, the end of the substrate close to the sulfur source is supported by a quartz column, and the other end is in contact with the metal molybdenum foil, and the quartz boat is located in the deposition temperature zone;

[0010] S3, the quartz tube is first evacuated, then inert gas is introduced into the quartz tube, the sulfur source temperature zone and the deposition temperature zone are heated, the target temperature of the sulfur source temperature zone is 220-240 DEG C, the target temperature of the deposition temperature zone is 800-850 DEG C, and the two temperature zones are simultaneously raised to the set target temperature value;

[0011] S4, the sulfur vapor is transported to the deposition temperature zone by the inert gas to react with rhenium and molybdenum, the reaction time is 15-20 minutes, a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure is obtained on the substrate, and the reaction is cooled to room temperature under the protection of inert gas after the reaction is completed.

[0012] Preferably, the size of the Si / SiO2 substrate is 1cm*2cm.

[0013] Preferably, the Si / SiO2 substrate is a silicon wafer without a catalyst and a seed layer.

[0014] Preferably, the molybdenum source is a metal molybdenum foil oxidized in air at 350℃ for two hours, and the rhenium source is a metal rhenium foil oxidized in air at 350℃ for two hours.

[0015] Preferably, the metal molybdenum foil has a mass purity of 99.99%, a thickness of 0.1mm, and a size of 1.2cm x 3cm, the metal rhenium foil has a mass purity of 99.99%, a thickness of 0.04mm, and a size of 0.5cm x 0.5cm, and the sulfur powder has a mass purity of 99.99% and is added in an amount of 200-400mg.

[0016] Preferably, the sulfur source quartz boat is located close to the air inlet end of the tube furnace.

[0017] Preferably, the quartz column is vertically supported and has a height of 0.7-1.0mm, and the bottom of the quartz column is in contact with the metal molybdenum foil.

[0018] Preferably, the distance between the two quartz boats is 16-18cm.

[0019] Preferably, the inert gas is argon.

[0020] Preferably, in S3, after the quartz tube is evacuated, the quartz tube is cleaned with 500 cubic centimeters / minute of argon for 30 minutes.

[0021] Preferably, in S4, the operation of simultaneously raising the temperature of the two temperature zones to the set target temperature value is as follows: first, the deposition temperature zone is raised to 600℃ at a temperature raising rate of 22℃ / min, and then the sulfur source temperature zone is raised.

[0022] Preferably, the argon flow rate during the temperature raising stage and the reaction stage of the two temperature zones is 70 cubic centimeters / minute.

[0023] The present application has the following beneficial effects: the present application realizes the preparation of a rhenium sulfide / molybdenum sulfide vertical heterostructure with two-dimensional rhenium sulfide as the bottom layer and two-dimensional molybdenum sulfide as the top layer by one-step chemical vapor deposition. The method is based on the difference in the evaporation temperature of the rhenium / molybdenum source and the difference in the growth temperature of the rhenium sulfide / molybdenum sulfide, thereby realizing the growth of the two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure by one-step chemical vapor deposition. The method provided can be extended to the preparation of other two-dimensional vertical heterostructures, i.e., other two-dimensional vertical heterostructures are synthesized on different substrates by a similar method. The method is simple, low in cost, catalyst-free, and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The figure is a schematic diagram of the device used for the preparation of the two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure.

[0025] Figure 2 The figure is a low-power optical microscope (OM) photo of the ReS2 / MoS2 vertical heterostructure prepared in Example 1.

[0026] Figure 3 A high-magnification optical microscope (OM) photo of the ReS2 / MoS2 vertical heterostructure prepared in Example 1 of the present application.

[0027] Figure 4 A Raman spectrum of the ReS2 / MoS2 vertical heterostructure prepared in Example 1 of the present application.

[0028] Figure 5 A photoluminescence spectrum of the ReS2 / MoS2 vertical heterostructure prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0029] The structure or technical terms used in the present application are further described below. These descriptions are only used to illustrate how the present application is implemented and cannot constitute any limitation on the present application.

[0030] Example 1

[0031] A preparation method of a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure, which is prepared by chemical vapor deposition, using Si / SiO2 as a deposition substrate, a metal rhenium foil as a rhenium source, a metal molybdenum foil as a molybdenum source, and reacting with a sulfur source sulfur powder. The preparation is carried out in a double-temperature-zone horizontal tube furnace, and a device schematic diagram is shown in Figure 1 The temperature zone 1 is a sulfur source temperature zone, and the temperature zone 2 is a deposition temperature zone, and the preparation method specifically includes the following steps:

[0032] S1, selecting a Si / SiO2 substrate without a catalyst and a seed layer, and the substrate size is 1 cm x 2 cm.

[0033] S2, the double-temperature-zone horizontal tube furnace is sequentially set as a sulfur source temperature zone and a deposition temperature zone according to the airflow direction; a quartz boat containing 300 milligrams of sulfur powder is placed in the sulfur source temperature zone, a quartz boat containing a rhenium (Re) source, a molybdenum (Mo) source, and a growth substrate is placed in the center of the deposition temperature zone, a small metal rhenium foil with an oxidized thickness of 0.04 mm and a size of 0.5 cm x 0.5 cm is laid on one end of a large metal molybdenum foil with an oxidized thickness of 0.1 mm and a size of 1.2 cm x 3 cm, and the end is close to the sulfur source temperature zone, the area of the metal rhenium foil is smaller than that of the metal molybdenum foil, the substrate is inverted and placed directly above the metal molybdenum foil, one end of the substrate is vertically supported by a quartz column with a height of about 0.7 mm, the other end directly contacts the metal molybdenum foil, the quartz column is close to the sulfur source side, and the bottom of the quartz column contacts the metal molybdenum foil, the two quartz boats are placed in the same quartz tube with a spacing of 16 cm, and the quartz tube is placed in the tube furnace.

[0034] S3. Before heating, flush the furnace with 500 cubic centimeters / minute of high-purity argon (99.99%) for 30 minutes to remove residual oxygen and moisture. Under the protection of 70 cubic centimeters / minute of high-purity argon, heat the deposition temperature zone to 600°C at a heating rate of 22°C / min. At this time, the sulfur source temperature zone begins to heat. The target temperature of the sulfur source temperature zone is 230°C, and the target temperature of the deposition temperature zone is 825°C. Both temperature zones are simultaneously raised to the set target temperature values.

[0035] S4. Sulfur vapor generated in the sulfur source temperature zone is transported by argon to the deposition temperature zone to react with molybdenum and rhenium. The reaction time is 15 minutes, resulting in a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure on the substrate. After the reaction, the mixture is cooled to room temperature under argon protection. The resulting two-dimensional ReS2 / MoS2 vertical heterojunction material is a crystal composed of two different sizes of stacked crystals.

[0036] Figure 2 The image shown is a low-magnification optical photograph of the prepared two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure. It can be seen that the prepared sample is an independent, dispersed prismatic or triangular crystal, as indicated by the white arrow in the figure.

[0037] Figure 3 The image shown is a high-magnification optical photograph of a single prismatic crystal. It can be seen that the center (2) of the crystal is darker in color, while the edge region (1) is lighter in color, indicating a change in thickness. The shape of the dark central region is irregular, and the side length of the large prismatic crystal is approximately 20 micrometers.

[0038] Figure 4 As shown Figure 3 Raman spectra of the dark central region (2) and the light peripheral region (1) of the triangular vertical heterostructure. As can be seen from the figure, the difference between the two spectra is that the central region has an extra Raman peak, located at 380.3 cm⁻¹. -1 and 402.7cm -1 These two Raman peaks can be attributed to the E2 of hexagonal MoS2. 1 2g (Γ) and A 1g The difference between the (Γ) modulus and the modulus is only 20.4 cm. -1 This indicates the presence of a bilayer of MoS2 in the heterostructure. Furthermore, Raman peaks labeled 1-8 also appear at positions 1-2, with essentially the same peak position and shape. These Raman peaks can be attributed to the E-type of multilayer 1T-ReS2. 2g and A 1g The vibrational modes, as well as the vibrational modes generated by the disorder caused by symmetric splitting, can be identified by Raman analysis at different locations. It can be seen that the bottom of the crystal is a multilayer rhenium sulfide, and the middle and top are a double layer of molybdenum sulfide.

[0039] Figure 5 The photoluminescence spectrum of the center dark region (2) and the peripheral light region (1) of the triangular vertical heterostructure is shown Figure 3 The photoluminescence spectrum of the center dark region (2) and the peripheral light region (1) of the triangular vertical heterostructure is shown The photoluminescence spectrum of the center dark region (2) and the peripheral light region (1) of the triangular vertical heterostructure is shown

[0040] In summary, the present application is to use chemical vapor deposition method, based on the evaporation temperature of metal molybdenum foil and metal rhenium foil, and the growth temperature of molybdenum disulfide and rhenium disulfide is different, so as to realize the growth of two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure.

[0041] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure, characterized in that, Includes the following steps: S1. Using Si / SiO2 as the substrate, rhenium foil as the rhenium source, molybdenum foil as the molybdenum source, and sulfur powder as the sulfur source; S2. The dual-temperature zone horizontal tube furnace is set as the sulfur source temperature zone and the deposition temperature zone according to the airflow direction. Two quartz boats are placed in the same quartz tube, which is placed in the tube furnace. One quartz boat holds the sulfur source in the sulfur source temperature zone, and the other holds the rhenium source, molybdenum source, and growth substrate. The oxidized rhenium foil is laid flat on one end of the oxidized molybdenum foil, with this end close to the sulfur source temperature zone. The substrate is inverted and placed directly above the molybdenum foil. The end of the substrate close to the sulfur source is supported by a quartz pillar, and the other end is in contact with the molybdenum foil. This quartz boat is located in the deposition temperature zone. S3. First, evacuate the quartz tube, then introduce inert gas into the quartz tube to raise the temperature of the sulfur source temperature zone and the deposition temperature zone. The target temperature of the sulfur source temperature zone is 230℃, and the target temperature of the deposition temperature zone is 825℃. Both temperature zones are raised to the set target temperature values ​​at the same time. S4. Sulfur vapor is transported to the deposition temperature zone by inert gas to react with rhenium and molybdenum. The reaction time is 15 minutes, resulting in a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure on the substrate. After the reaction, the structure is cooled to room temperature under inert gas protection. The bottom of the two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure is multilayer rhenium sulfide, and the middle and top are double layers of molybdenum sulfide.

2. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 1, characterized in that, The Si / SiO2 substrate is a silicon wafer without catalyst and seed layer, with a size of 1cm × 2cm.

3. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 1, characterized in that, The molybdenum source was a molybdenum foil oxidized in air at 350°C for two hours, and the rhenium source was a rhenium foil oxidized in air at 350°C for two hours.

4. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 1, characterized in that, The molybdenum foil has a purity of 99.99%, a thickness of 0.1 mm, and a size of 1.2 cm × 3 cm. The rhenium foil has a purity of 99.99%, a thickness of 0.04 mm, and a size of 0.5 cm × 0.5 cm. The sulfur powder has a purity of 99.99% and is added in an amount of 200–400 mg.

5. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 1, characterized in that, The sulfur source quartz boat is located near the gas inlet end of the tubular furnace.

6. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 1, characterized in that, The quartz pillars are vertically supported, with their bottoms in contact with the molybdenum foil. The height of the pillars is 0.7-1.0 mm, and the distance between the two quartz boats is 16-18 cm.

7. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 1, characterized in that, The inert gas is argon.

8. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 7, characterized in that, In S3, after evacuating the quartz tube, the quartz tube is cleaned with argon gas at a flow rate of 500 cubic centimeters per minute for 30 minutes.

9. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 7, characterized in that, In S4, the operation of simultaneously heating two temperature zones to the set target temperature value is as follows: first, the deposition temperature zone is heated to 600℃ at a heating rate of 22℃ / min, and then the sulfur source temperature zone is heated.

10. The method for preparing a two-dimensional rhenium sulfide-molybdenum sulfide vertical heterostructure as described in claim 7, characterized in that, The argon gas introduction rate during both the heating and reaction phases in the two temperature zones was 70 cubic centimeters per minute.

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