A method for growing a layered tungsten disulfide thin film on a photonic chip and the thin film

Abstract

This invention relates to the field of semiconductor materials technology, specifically to a method and film for growing layered tungsten disulfide thin films on photonic chips, comprising the following steps: using tungsten disulfide solid powder as the growth raw material, placing the growth raw material in the heating zone of a tube furnace, and placing the photonic chip on which tungsten disulfide is to be grown in the heat preservation zone of the tube furnace; introducing a protective gas into the tube furnace at a flow rate of 40-80 sccm, with the gas flow direction from the heating zone to the heat preservation zone; heating the area containing the tungsten disulfide solid powder to the tungsten disulfide growth temperature and maintaining the temperature to achieve the growth of layered tungsten disulfide thin films on the photonic chip; this invention avoids the growth of blocky or dendritic scattering sources, thereby improving the size of the film.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials technology, and more specifically to a method and a thin film for growing layered tungsten disulfide films on photonic chips. Background Technology

[0002] Layered transition metal dichalcogenide (TMDC) semiconductor thin films possess excellent optical and electrical properties, showing broad application prospects in the field of integrated optoelectronic chips. When the thickness of TMDC films is reduced from multiple atoms to a single atom, the material transforms from an indirect bandgap semiconductor to a direct bandgap semiconductor, resulting in a series of novel physical phenomena. Furthermore, when TMDCs become monolayers, they exhibit strong second-order nonlinear optical properties, showing broad application prospects in fields such as quantum light sources.

[0003] Graphene was initially obtained through the mechanical exfoliation of bulk graphite, which opened the door to the research of layered TMDCs. Layered tungsten disulfide (WS2), a typical representative of TMDCs, can also be obtained through the mechanical exfoliation of bulk WS2 and then transferred onto photonic chips for subsequent research. Transferring mechanically exfoliated layered WS2 onto photonic chips to achieve the integration of two-dimensional materials with photonic chips is simple, has low equipment dependence, and is widely used in laboratory research. However, photonic chips are non-flat substrates with waveguide steps hundreds of nanometers high on their surface. Therefore, when transferring atomically thin two-dimensional materials onto photonic chips, the two-dimensional material can only be transferred to the upper surface of the waveguide steps. Furthermore, because the height of the waveguide steps is relatively high compared to the thickness of the two-dimensional material, the transferred two-dimensional material is prone to wrinkling and breakage. In addition, the two-dimensional material transfer method has poor reproducibility and cannot be scaled up on a large scale.

[0004] To address the drawbacks of the aforementioned transfer methods, it is possible to directly grow layered WS2 on photonic chips with micro / nano structures. WS2 growth can be categorized into two methods: chemical vapor deposition (CVD) and physical vapor deposition (PVD). CVD typically requires pretreatment of the photonic chip surface and the establishment of two temperature zones within the tube furnace, where a chemical reaction is used to grow the WS2 semiconductor film on the photonic chip surface. PVD is simpler, generally requiring no pretreatment of the photonic chip; the WS2 powder is directly heated without any chemical reaction, resulting in a layered WS2 semiconductor film directly on the photonic chip surface.

[0005] Conventional physical vapor deposition (PVD) is reverse PVD, meaning that the gas flow is reversed during the heating phase and forward during the growth phase. For example, Chinese patent application number 201911032943.1 discloses a single-atom-layer tungsten disulfide (WS2) two-dimensional material and its preparation method and application via reverse PVD. This method uses a reverse gas flow to grow a single layer of WS2 with a feature size of 50-200 micrometers on a planar silicon oxide / silicon (SiO2 / Si) substrate. This method is not suitable for directly growing layered WS2 on the surface of photonic chips; the results are not ideal, and blocky or dendritic scattering sources may grow. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and a film for growing layered tungsten disulfide thin films on photonic chips, avoiding the growth of blocky or dendritic scattering sources and improving the size of the film.

[0007] This invention provides a method for growing a layered tungsten disulfide thin film on a photonic chip, comprising the following steps: using tungsten disulfide solid powder as the growth raw material, placing the growth raw material in the heating zone of a tube furnace, and placing the photonic chip on which tungsten disulfide is to be grown in the heat preservation zone of the tube furnace;

[0008] A protective gas is introduced into the tube furnace at a flow rate of 40-80 sccm, with the gas flow direction from the heating zone to the heat preservation zone. The area containing the tungsten disulfide solid powder is heated to the tungsten disulfide growth temperature and then kept at that temperature to achieve the growth of a layered tungsten disulfide thin film on the photonic chip.

[0009] In this invention, during both the heating and holding stages, the protective gas flow direction is from the heating zone to the holding zone. The growth method involves heating and sublimating tungsten disulfide solid powder, which is then deposited on a photonic chip following the protective gas flow direction. During the holding process, it grows into a layered semiconductor thin film, and the growth process does not involve any chemical processes. The mass of the growth raw material, i.e., tungsten disulfide solid powder, is 0.3-0.6 grams.

[0010] As one embodiment, the photonic chip that requires the growth of tungsten disulfide has raised silicon nitride straight waveguides and micro-ring micro-nano structures on its surface, with a step height of 600-1000 nanometers and a photonic chip size of 1.5 cm * 3 cm.

[0011] In one embodiment, the photonic chip to be grown as tungsten disulfide is placed in the center of the heat preservation zone of the tube furnace, and the distance between the center of the raw material and the center of the photonic chip is 7-12 cm.

[0012] In one embodiment, the protective gas is argon.

[0013] In one embodiment, a protective gas is introduced to clean the gas path before the raw material is grown. The flow rate of the protective gas is 300-500 sccm, and the cleaning time is 3-10 minutes.

[0014] In one embodiment, during the process of heating the area containing the tungsten disulfide solid powder to the tungsten disulfide growth temperature, the flow rate of the protective gas is 40-80 sccm, and the flow direction of the protective gas is from the heating zone to the heat preservation zone.

[0015] In one embodiment, the growth temperature is 1050-1180℃ and the holding time is 10-15 min.

[0016] In one embodiment, during the heat preservation process, the flow rate of the protective gas is 50-80 sccm, and the airflow direction of the protective gas is from the heating zone to the heat preservation zone.

[0017] As one embodiment, after the growth process is completed, the tube furnace is naturally cooled to complete the growth of the layered tungsten disulfide film on the photonic chip.

[0018] Protective gas is introduced during the heating, heat preservation, and natural cooling processes of the tubular furnace.

[0019] This invention provides a thin film prepared using the method described above for growing layered tungsten disulfide thin films on photonic chips.

[0020] The beneficial effects of this invention are:

[0021] 1. Compared to the publicly reported reverse-flow physical vapor deposition method for preparing single-atom-layer WS2, this invention employs a forward airflow throughout the entire material growth process. The protective gas direction is from WS2 solid powder to the photonic chip containing the WS2 semiconductor thin film to be grown. The main reason for using the reverse airflow technique is to prevent WS2 from growing before reaching the growth temperature; however, experiments show that it produces blocky or dendritic scattering sources on the waveguide surface. The conventional approach to reduce or avoid the growth of blocky or dendritic scattering sources on the waveguide surface is to reduce the flow rate of the protective gas during material growth to prevent WS2 accumulation and the formation of blocky or dendritic scattering sources. This invention also uses a forward airflow during the heating stage and maintains a constant flow rate. The reason it can avoid the formation of blocky or dendritic scattering sources is likely because this invention maintains a forward airflow direction from the WS2 powder to the photonic chip until the growth temperature is reached, thereby providing more WS2 nucleation sites on the waveguide and avoiding the blocky or dendritic scattering sources on the waveguide surface that occur during the reverse airflow growth method, thus preserving the multifunctionality of the photonic chip. It is generally believed that providing WS2 nucleation sites too early will lead to accumulation. However, the experiments in this application show that during the heating stage, before the temperature rises to the growth stage, allowing the photonic chip to accumulate some nucleation sites and controlling the flow rate of the protective gas to 40-80 sccm actually solves the growth problem of bulk or dendritic scattering sources and allows for a larger film size. This is an unexpected achievement for the inventors.

[0022] 2. Compared with the publicly reported chemical vapor deposition method for preparing layered WS2 semiconductor thin films, the present invention only requires one solid WS2 powder as the growth raw material, and does not require setting up multiple heating zones. Layered WS2 semiconductor thin films can be directly grown on photonic chips through a one-step physical process. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the tube furnace structure and airflow for growing layered WS2 semiconductor thin films according to an embodiment of the present invention.

[0024] Figure 2 This is a scanning electron microscope image of the WS2 thin film obtained in Example 1 of the present invention.

[0025] Figure 3 This is a scanning electron microscope image of the WS2 thin film obtained in Example 2 of the present invention.

[0026] Figure 4 This is a scanning electron microscope image of the WS2 thin film obtained in Example 3 of the present invention.

[0027] Figure 5 This is a scanning electron microscope image of the WS2 thin film obtained in Comparative Example 1.

[0028] Figure 6 This is a scanning electron microscope image of the WS2 thin film obtained in Comparative Example 2.

[0029] Figure 7 This is a scanning electron microscope image of the WS2 thin film obtained in Comparative Example 3.

[0030] In the diagram, 1 is the insulation zone, 2 is the heating zone, and 3 is the photonic chip. Detailed Implementation Plan

[0031] Example 1

[0032] A method for growing layered tungsten disulfide thin films on photonic chips, employing methods such as... Figure 1 The tube furnace structure shown is used, with WS2 solid powder as the growth raw material. 0.3g of WS2 solid powder is weighed and placed in a quartz boat, and then the quartz boat containing 0.3g of WS2 solid powder is placed in the heating zone 2 of the tube furnace. A clean silicon-based photonic chip 3 with a silicon nitride microring structure (1.5 cm x 3 cm, waveguide step height approximately 600 nm) was mounted on a quartz boat and placed in the center of the incubation zone 1 of a tube furnace. The center of the growth material was approximately 7 cm from the center of the substrate. The tube furnace was then sealed. Argon gas was introduced as a protective gas, with a forward airflow (from WS2 solid powder to the photonic chip) at a flow rate of 300 sccm. This flow rate was maintained for 5 minutes to clean the pipes and maintain an inert gas atmosphere for subsequent material growth. The flow rate of the argon gas was then adjusted to 80 sccm, and the tube furnace was heated. The furnace was heated from room temperature to 1100°C over 45 minutes and held at this temperature for 10 minutes. Heating was then stopped, and the furnace was allowed to cool naturally to room temperature, resulting in a layered WS2 semiconductor thin film grown on the photonic chip. Throughout the heating and natural cooling process, the direction and flow rate of the protective gas remained constant, and the fabrication process was carried out at atmospheric pressure.

[0033] Figure 2 This is a scanning electron microscope (SEM) image of the WS2 semiconductor thin film obtained in Example 1 of this invention. As can be seen from the image, the continuity of the WS2 semiconductor thin film growth was not affected by the silicon nitride microring protrusions on the SiO2 / Si substrate. The film shape is approximately triangular, with a feature size of about 280 micrometers. Furthermore, no blocky or dendritic scattering sources were observed on the silicon nitride microrings.

[0034] Example 2

[0035] A method for growing layered tungsten disulfide thin films on photonic chips includes the following steps: weighing 0.4g of WS2 solid powder and placing it in a quartz boat, and then placing the quartz boat containing 0.4g of WS2 solid powder in the heating zone 2 of a tube furnace. A clean silicon-based photonic chip 3 with a silicon nitride microring structure (1.5 cm x 3 cm, waveguide step height approximately 600 nm) was mounted on a quartz boat and placed in the center of the incubation zone 1 of a tube furnace. The center of the growth material was approximately 10 cm from the center of the substrate. The tube furnace was then sealed. Argon gas was introduced as a protective gas, with a forward airflow (from WS2 solid powder to the photonic chip) at a flow rate of 300 sccm. This flow rate was maintained for 5 minutes to clean the pipes and maintain an inert gas atmosphere for subsequent material growth. The flow rate of the argon gas was then adjusted to 50 sccm, and the tube furnace was heated. The furnace was heated from room temperature to 1170°C over 46 minutes and held at this temperature for 12 minutes. Heating was then stopped, and the furnace was allowed to cool naturally to room temperature, thus achieving the growth of a layered WS2 semiconductor thin film on the photonic chip with the silicon nitride microring protrusion micro / nano structure. Throughout the heating and natural cooling process, the direction and flow rate of the protective gas remained constant, and the fabrication process was carried out at atmospheric pressure.

[0036] Figure 3 This is a scanning electron microscope image of the WS2 semiconductor thin film obtained in Example 2 of the present invention. As can be seen from the image, the continuity of the WS2 semiconductor thin film growth was not affected by the silicon nitride microring protrusions on the SiO2 / Si substrate. The film shape is approximately triangular, with a feature size of about 300 micrometers. Furthermore, no blocky or dendritic scattering sources appeared on the silicon nitride microrings.

[0037] Example 3

[0038] A method for growing layered tungsten disulfide thin films on photonic chips includes the following steps: weighing 0.4g of WS2 solid powder and placing it in a quartz boat, and then placing the quartz boat containing 0.4g of WS2 solid powder in the heating zone 2 of a tube furnace. A clean silicon-based photonic chip 3 with a silicon nitride microring structure (1.5 cm * 3 cm in size, with a waveguide step height of approximately 600 nm) was mounted on a quartz boat and placed in the center of the incubation zone 1 of a tube furnace. The center of the growth material was approximately 10 cm from the center of the substrate. The tube furnace was then sealed. Argon gas was introduced as a protective gas, with a forward airflow (from WS2 solid powder to the substrate) at a flow rate of 300 sccm. This flow rate was maintained for 5 minutes to clean the pipes and maintain an inert gas atmosphere for subsequent material growth. The flow rate of the argon gas was then adjusted to 50 sccm, and the tube furnace was heated. The furnace was heated from room temperature to 1170°C over 46 minutes and held at this temperature for 15 minutes. Heating was then stopped, and the furnace was allowed to cool naturally to room temperature, thus achieving the growth of a layered WS2 semiconductor thin film on the SiO2 / Si photonic chip with silicon nitride microring protrusions. Throughout the heating and natural cooling process, the direction and flow rate of the protective gas remained constant, and the fabrication process was carried out at atmospheric pressure.

[0039] Figure 4 This is a scanning electron microscope (SEM) image of the WS2 semiconductor thin film obtained in Example 3 of this invention. As can be seen from the image, the continuity of the WS2 semiconductor thin film growth was not affected by the silicon nitride microring protrusions on the SiO2 / Si substrate; and due to the extended holding time at the WS2 growth temperature compared to Examples 1-2, the continuous size of the WS2 semiconductor thin film further increased to approximately 340 micrometers. Similarly, no blocky or dendritic scattering sources appeared on the silicon nitride microrings.

[0040] Comparative Example 1

[0041] A method for growing layered tungsten disulfide thin films on photonic chips, with specific growth parameters and results as follows.

[0042] Preparation: The prepared silicon nitride photonic chip was cut into 1.5 cm * 3 cm pieces and then ultrasonically cleaned in pure water. 0.05 g of WS2 powder was placed in a quartz boat and placed in heating zone 2. The prepared silicon nitride photonic chip 3 was then placed in the center of the entire tube furnace insulation zone 1. Initially, the airflow direction was from the photonic chip to the WS2 powder, and then the temperature was increased. When the temperature reached 1100℃, the direction of the inert gas was changed so that the airflow direction was from the WS2 powder to the photonic chip. The airflow velocity was then adjusted to 80 sccm, and the temperature was maintained within this range for 7 minutes to allow WS2 to grow on the photonic chip with micro-nano structures. Then the temperature was lowered to 1000℃, and the airflow velocity was adjusted to 60 sccm. When the temperature was lowered to 900℃, the gas flow velocity was adjusted to 20 sccm. The photonic chip was then removed after cooling to room temperature. To observe the quality of WS2 grown on a photonic chip with micro / nano structures on a SiO2 / Si substrate using reverse physical vapor deposition.

[0043] Figure 5 The image shows the scanning electron microscope (SEM) results of growing layered WS2 on a photonic chip with a silicon nitride microring resonator micro / nano structure using the method described above (refer to Example 1 in Chinese Patent Application No. 201911032943.1). It can be seen that the characteristic size of the WS2 is 100 micrometers, reaching a size comparable to the layered WS2 grown on a SiO2 / Si flat substrate proposed in Chinese Patent Application No. 201911032943.1; however, we can also observe that, due to the protrusion height of the silicon nitride microrings being close to one micrometer, many blocky WS2 scattering sources are grown on the microrings. The main reason for using a reverse airflow is to prevent WS2 from starting to grow on the substrate before reaching the growth temperature. Figure 5 As can be seen, when Comparative Example 1 is grown on a silicon nitride microring resonator, it has a large number of WS2 block scattering sources. These block scattering sources will prevent light from propagating continuously in the silicon nitride waveguide, thus defeating the purpose of the photonic chip. From Figure 5 The growth results shown indicate that the method of growing WS2 on a SiO2 / Si flat substrate using reverse physical vapor deposition in Comparative Example 1 is not suitable for directly growing layered WS2 semiconductor thin films on photonic chips with micro- and nano-structures.

[0044] Comparative Example 2

[0045] A method for growing layered tungsten disulfide thin films on photonic chips, with specific growth parameters and results as follows.

[0046] Preparation: The prepared silicon nitride photonic chip was cut into small pieces of 1.5 cm * 3 cm and then placed in pure water for ultrasonic cleaning; 0.06 g of WS2 powder was placed in a quartz boat and placed in the middle of the heating zone 2, and the prepared silicon nitride photonic chip 3 was placed in the center of the entire tube furnace insulation zone 1. Initially, the gas flow direction was from the photonic chip to the WS2 powder, and then the temperature was increased. When the temperature reached 1200℃, the direction of the inert gas was changed so that the gas flow direction was from the WS2 powder to the photonic chip, and then the gas flow rate was adjusted to 30 sccm. The temperature was maintained within this range for 10 minutes to allow WS2 to grow on the photonic chip with micro-nano structures. Then the temperature was lowered to 950℃, and the gas flow rate was adjusted to 50 sccm. When the temperature was lowered to 800℃, the gas flow rate was adjusted to 20 sccm. After cooling to room temperature, the photonic chip was removed, and the quality of WS2 grown on the photonic chip with micro-nano structures on the surface was observed by reverse physical vapor deposition on a SiO2 / Si substrate.

[0047] Figure 6 The image shows the scanning electron microscope (SEM) results of growing layered WS2 on a photonic chip with a silicon nitride microring resonant cavity micro / nano structure using the method described in Comparative Example 2. It can be seen that the feature size of the WS2 is approximately 200 micrometers. This increase in feature size is due to the use of a higher growth temperature, a lower gas flow rate during growth, and a longer holding time compared to the method described in Comparative Example 1. It also reaches a size comparable to the layered WS2 grown on a SiO2 / Si flat substrate proposed in Chinese Patent Application No. 201911032943.1. However, we can also observe that, due to the near-micrometer protrusion height of the silicon nitride microrings, numerous WS2 dendritic scattering sources are grown on the microrings. The main reason for using a reverse gas flow is to prevent WS2 from starting to grow on the substrate before reaching the growth temperature. Figure 6 As can be seen from the comparison, when Comparative Example 2 is grown on a silicon nitride microring resonator, a large number of WS2 dendritic scattering sources are generated. These dendritic scattering sources will prevent light from propagating continuously in the silicon nitride waveguide, thus negating the function of the photonic chip. From Figure 6 The growth results shown indicate that the method of growing WS2 on a SiO2 / Si flat substrate using reverse physical vapor deposition is not suitable for directly growing layered WS2 semiconductor thin films on photonic chips with micro- and nano-structures.

[0048] Comparative Examples 1-2 demonstrate the direct growth of layered WS2 crystals with feature sizes exceeding 100 nanometers on the surface of photonic chips with micro / nano structures, achieving the same crystal size effect as the WS2 crystals grown on SiO2 / Si substrates proposed in this patent. However, it is noted that the reverse airflow method failed to prevent the growth of bulk crystals in the circumferential region of the layered WS2 grown on the silicon nitride microrings. Figure 5 ) or dendritic ( Figure 6 The scattering sources will prevent light from propagating in the silicon nitride microring, thus negating the function of the integrated photonic chip.

[0049] This invention ensures that a large area of ​​layered WS2 semiconductor thin film can be grown on the surface of silicon nitride microrings while avoiding the growth of blocky or dendritic scattering sources, thereby increasing the multifunctionality of silicon nitride photonic chips without causing them to lose their functionality.

[0050] Comparative Example 3

[0051] A method for growing layered tungsten disulfide thin films on photonic chips, with specific growth parameters and results as follows.

[0052] Preparation: The prepared silicon nitride photonic chip was cut into 1.5 cm * 3 cm pieces and then ultrasonically cleaned in pure water. 0.3 g of WS2 powder was placed in a quartz boat and positioned at the center of heating zone 2. The prepared silicon nitride photonic chip 3 (1.5 cm * 3 cm, waveguide step height approximately 600 nm) was then placed on the quartz boat at the center of the incubation zone 1 of the tube furnace, with the center of the growth material approximately 8 cm from the center of the substrate. The tube furnace was then sealed. Argon gas was introduced as a protective gas, with a forward airflow (from WS2 solid powder to the photonic chip) at a flow rate of 300 sccm. This flow rate was maintained for 5 minutes to clean the pipes and maintain an inert gas atmosphere for subsequent material growth. Subsequently, the flow rate of the argon gas was adjusted to 90 sccm, and the program was set to heat the tube furnace. The tube furnace was heated from room temperature to 1100°C over 45 minutes and then held at this temperature for 10 minutes. Heating was then stopped, and the tube furnace was allowed to cool naturally to room temperature. The WS2 grown on the photonic chip was then observed. Throughout the heating and natural cooling process, the direction and flow rate of the protective gas remain constant, and the preparation process is carried out at atmospheric pressure.

[0053] This invention discloses a method for growing layered tungsten disulfide thin films on photonic chips. During material growth, the flow rate of the protective gas needs to be 40-80 sccm. In this comparative example, the gas flow rate during material growth is set to 90 sccm. Figure 7 It can be seen that if the gas flow rate is too high, the growth of layered WS2 thin films will not be achieved, resulting in the growth of WS2 dendritic scattering sources on silicon nitride microrings, thus losing the function of the photonic chip.

[0054] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0055] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A method for growing a layered tungsten disulfide thin film on a photonic chip, characterized in that, Includes the following steps: Using tungsten disulfide solid powder as the growth raw material, the growth raw material is placed in the heating zone of a tube furnace, and the photonic chip to be grown with tungsten disulfide is placed in the heat preservation zone of the tube furnace; before the growth of the growth raw material, a protective gas is introduced to clean the gas path, the flow rate of the protective gas is 300-500 sccm, and the cleaning time is 3-10 minutes. A protective gas is introduced into a tube furnace at a flow rate of 40-80 sccm, with the gas flowing from the heating zone to the holding zone. The area containing the tungsten disulfide solid powder is heated to the tungsten disulfide growth temperature, which is 1050-1180℃, and held at this temperature for 10-15 minutes, with the protective gas flowing from the heating zone to the holding zone at a flow rate of 40-80 sccm. This achieves the growth of a layered tungsten disulfide thin film on a photonic chip. After the growth process is completed, the tube furnace is naturally cooled, thus completing the growth of the layered tungsten disulfide film on the photonic chip. In particular, protective gas is introduced during the heating, heat preservation, and natural cooling processes of the tubular furnace. The photonic chip that requires the growth of tungsten disulfide has raised silicon nitride straight waveguides and micro-ring micro-nano structures on its surface, with a step height of 600-1000 nanometers. The photonic chip for which tungsten disulfide is to be grown is placed in the center of the heat preservation zone of the tube furnace, and the distance between the center of the raw material and the center of the photonic chip is 7-12 cm.

2. The method of claim 1, wherein the layer of tungsten disulfide is grown on the photonic chip by a chemical vapor deposition process. The protective gas is argon.

3. The method of claim 1, wherein the layer of tungsten disulfide is grown on a photonic chip. During the process of heating the area containing the tungsten disulfide solid powder to the tungsten disulfide growth temperature, the flow rate of the protective gas is 50-80 sccm, and the flow direction of the protective gas is from the heating zone to the heat preservation zone.

4. A thin film, characterized in that, It was prepared by the method of growing layered tungsten disulfide thin films on photonic chips as described in any one of claims 1-3.

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