Method for preparing metal sulfide thin film material through magnetron reactive sputtering at room temperature

Abstract

The invention belongs to the technical field of thin film preparation, and particularly relates to a method for preparing a metal sulfide thin film material through magnetron reactive sputtering at room temperature. The preparation method comprises the following steps: taking a metal target material with good heat conduction and electric conduction and elemental sulfur as raw materials, keeping a substrate at room temperature, heating and evaporating sulfur powder by adopting a resistor to form sulfur steam, and then reacting and depositing on the substrate by adopting a magnetron sputtering metal target material to obtain the metal sulfide film. Before formal sputtering deposition, a metal target material is subjected to pre-sputtering for more than or equal to 5 min, a substrate baffle is opened after pre-sputtering is finished, the formal sputtering metal target material is subjected to reaction deposition to obtain the metal sulfide film, the formal sputtering time is 5-60 min, the pre-sputtering power and the formal sputtering air pressure are the same, the power is 60-150 W, and the sputtering air pressure is 2.8-5 Pa. The method has the advantages of low raw material cost, no cracking in the target sputtering process, high deposition rate, avoidance of use of highly toxic gas H2S, room-temperature deposition, no need of annealing, simple operation and good repeatability.

Description

Technical Field

[0001] The invention belongs to the technical field of thin film preparation, and in particular relates to a method for preparing a metal sulfide thin film material by magnetron reactive sputtering at room temperature. Background Art

[0002] CdS is an important II-VI compound semiconductor, a metal sulfide, of the direct transition type, with a band gap of approximately 2.5 eV at room temperature. It exhibits excellent chemical stability, high transmittance, and optoelectronic properties, and therefore holds great promise for applications in solar cells, photodetectors, photocatalysis, and other fields. There are various methods for preparing CdS thin films, such as magnetron sputtering, vacuum evaporation, pulsed laser deposition, chemical water bath deposition, and spray pyrolysis. Magnetron sputtering offers advantages such as dense films, good adhesion, fast deposition rates, easy control, and scalability. It also avoids the hazards of chemical reagents and residual solutions used in chemical solution-based film preparation, which pose a threat to humans and the environment. It is a commonly used physical vapor deposition technique for preparing thin film materials.

[0003] Compound ceramic targets are often used in the preparation of CdS thin films by magnetron sputtering. Xiaobo Hu et al. used CdS films deposited by radio-frequency magnetron sputtering as buffer layers to fabricate Sb2Se3 thin-film solar cells. The optimized cells achieved an efficiency of 5.91% (see [5.91%-efficiency Sb2Se3 solar cells with a radio-frequency magnetron-sputtered CdS buffer layer[J]. Applied Materials Today, 2019, 16:367–374]). Shilin Wang et al. deposited Cu-doped CdS films by radio-frequency magnetron sputtering and studied the effect of Cu doping on their physical and photo-electrochemical properties (see [Influence of Cu doping on physical and photo-electrochemical properties of CdS thin films prepared by RF magnetron sputtering[J]. Materials Science in Semiconductor Processing, 2021, 133:105933]). However, compound ceramic targets are not only expensive but also prone to cracking during high-power sputtering. Le-Xi Shao et al. used a metal target to deposit ZnS metal sulfide thin films by magnetron reactive sputtering in an H2S and Ar atmosphere at a substrate temperature of 200°C. The resulting ZnS films can be used as buffer layers for thin-film solar cells (see "Zinc sulfide thin films deposited by RF reactive sputtering for photovoltaic applications[J]. Applied Surface Science, 2003, 212–213: 305–310"). However, this magnetron sputtering deposition method for preparing metal sulfide films involves the use of highly toxic H2S gas. Summary of the Invention

[0004] To address the above-mentioned defects and shortcomings of the prior art, the main purpose of the present invention is to provide a method for depositing metal sulfide thin films by magnetron reactive sputtering at room temperature. This method prevents the target material from cracking during the sputtering process and avoids the use of highly toxic gases.

[0005] The technical solution of this invention involves using a metal target with good thermal and electrical conductivity and elemental sulfur as raw materials. On a room-temperature substrate, sulfur powder is first evaporated using resistance heating to form sulfur vapor. This is then reactively deposited onto the substrate using magnetron sputtering to form a metal sulfide thin film. This method offers the advantages of low raw material costs, no target cracking during sputtering, fast deposition rates, avoidance of the highly toxic H2S gas, room-temperature deposition, no annealing required, simple operation, and excellent reproducibility.

[0006] The scheme adopted in the present invention is as follows: A method for depositing a metal sulfide thin film by magnetron reactive sputtering at room temperature comprises the following steps: (1) Clean the substrate, dry it, and place it on the substrate holder in the vacuum chamber; (2) Installing the single element metal target or alloy target at the corresponding target position in the vacuum chamber; (3) Weigh sulfur powder, place it in a steam boat, and install the steam boat at the corresponding evaporation station in the vacuum chamber; (4) Evacuate the vacuum chamber to a pressure less than 5×10 -3 Pa; (5) Turn on the resistance heating evaporation system to heat and evaporate the sulfur powder; (6) Fill with high-purity argon, turn on the RF power supply, and maintain the substrate at room temperature; before the formal sputtering deposition, pre-sputter the metal target for a time greater than or equal to 5 minutes. After the pre-sputtering is completed, open the substrate baffle and formally sputter the metal target for reactive deposition to obtain a metal sulfide film. The formal sputtering time is 5 minutes to 60 minutes. The power and sputtering pressure of the pre-sputtering and formal sputtering are the same, the power is 60W to 150W, and the sputtering pressure is 2.8Pa to 5Pa.

[0007] Furthermore, in step (1), the substrate material is quartz glass.

[0008] Preferably, in the above step (1) of cleaning the substrate, the substrate material is ultrasonically cleaned in deionized water, acetone and anhydrous ethanol for 10 minutes respectively, and then dried.

[0009] Furthermore, in the above step (2), the single element metal target is Cd with a purity of 99.99 wt.%, the alloy target is CdZn alloy (Zn doping concentrations are 10 at.%, 30 at.%, and 50 at.%), with a purity of 99.99 wt.%, and the distance between the target and the substrate is 13 cm.

[0010] Preferably, in the above step (3), the mass of the sulfur powder is 100-400 mg, the purity is 99.5 wt%, the steam boat is a molybdenum evaporation boat, and the distance between the steam boat and the substrate is 20 cm.

[0011] Preferably, in the above step (5), the substrate baffle is always closed, the resistance heating evaporation system is turned on, and the steam boat and sulfur powder are preheated for 30 seconds. After the preheating is completed, the current is increased to the target current for heating and evaporation to evaporate all the sulfur powder in the steam boat; the current for preheating the steam boat and sulfur powder is 30A, and the target current for heating and evaporation is 45A-75A.

[0012] Preferably, in step (6), the purity of the high-purity argon injected is 99.999 at.%, and the substrate holder rotation speed is 17 rpm. The purpose of pre-sputtering is to remove impurities on the surface of the target material. During the pre-sputtering process, the substrate baffle should be closed and opened after the pre-sputtering is completed.

[0013] Compared with the prior art, the technical effects of the present invention are as follows: (1) Using a metal target and sulfur powder, the substrate is kept at room temperature, and the sulfur powder is evaporated by resistance heating and the metal target is reactively deposited by magnetron sputtering to obtain a CdS film, and no annealing is required. The target material in the present invention is a metal target material, which is low in cost. There is no cracking of the target material during sputtering, and a larger power usage range can be achieved, while avoiding the use of highly toxic H2S gas.

[0014] (2) The CdS film prepared by the present invention has good reproducibility, simple operation, and can obtain high light transmittance. In addition, magnetron sputtering and resistance heating evaporation equipment have been industrialized and are relatively mature, and can be easily prepared and produced on a large scale. Therefore, the present invention provides a low-cost, fast deposition rate, room temperature deposition, no annealing required, safe and reliable method for the preparation and application and research of metal sulfide films. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] These and / or other aspects and advantages of the present invention will become more apparent and more easily understood from the following detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and tables, in which: Figure 1 Schematic diagram of the positional relationship in a vacuum coating machine for reactively depositing metal sulfide thin films using a method of resistive heating to evaporate sulfur powder and magnetron sputtering a metal target according to an embodiment of the present invention.

[0016] Figure 2 These are the XRD patterns and transmission spectra of the films prepared in Examples 1, 2, 3 of the present invention and Comparative Example 1.

[0017] Figure 3 Surface SEM images of the films prepared in Examples 1 and 2 of the present invention and Comparative Example 1.

[0018] Figure 4 These are EDS graphs of the films prepared in Examples 1 and 2 of the present invention and Comparative Example 1.

[0019] Figure 5These are the XRD patterns and transmission spectra of the CdS films prepared in Examples 2, 4, and 5 of the present invention.

[0020] Figure 6 These are the XRD patterns and transmission spectra of the CdS films prepared in Examples 2, 6, and 7 of the present invention.

[0021] Figure 7 These are cross-sectional SEM images of the CdS films prepared in Examples 2, 6, and 7 of the present invention.

[0022] Figure 8 These are the XRD patterns and transmission spectra of the CdS films prepared in Examples 2, 8, and 9 of the present invention.

[0023] Figure 9 These are the XRD patterns and transmission spectra of the CdS films prepared in Examples 2 and 10 of the present invention.

[0024] Figure 10 These are the XRD patterns and transmission spectra of the undoped and Zn-doped CdS films prepared in Examples 2, 11, 12, and 13 of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific examples. However, the embodiments of the present invention are not limited thereto. The description of the example embodiments is only for illustrative purposes and does not limit the present invention and its applications.

[0026] The specifications of the Cd or CdZn alloy target, evaporated molybdenum boat, high-purity Ar, and sulfur powder used in the following examples and comparative examples are as follows: the purity of the Cd metal target or CdZn alloy target is 99.99wt.%, the diameter is 60mm, and the thickness is 5mm; the evaporated molybdenum boat is 17mm wide, 100mm long, the outer dimension of the groove depth is 10mm, the outer dimension of the groove width is 15mm, and the outer dimension of the groove length is 40mm; the purity of the high-purity Ar is 99.999at.%; and the purity of the sulfur powder is 99.5wt.%. Example

[0027] (1) A quartz glass substrate with a size of 12 mm × 24 mm was selected. The substrate was first ultrasonically cleaned in deionized water, acetone, and anhydrous ethanol for 10 min, dried, and placed on the substrate holder in a vacuum coating machine. The distance between the target and the substrate was 130 mm. (2) Install the Cd metal target in the corresponding RF target position in the vacuum coating machine; (3) Weigh 300 mg of sulfur powder, ultrasonically clean the evaporation molybdenum boat with anhydrous ethanol for 5 minutes, dry it, then place the sulfur powder in the molybdenum boat and install it in the corresponding evaporation station in the vacuum coating machine; (4) Pump down the vacuum chamber of the vacuum coating machine to the background vacuum (less than 5×10 -3 Pa); (5) The vacuum in the vacuum chamber of the coating machine was cooled to 0.1 Pa, and the resistance heating evaporation system was turned on to preheat the molybdenum boat and sulfur powder. The preheating current was 30 A and the preheating time was 30 s. Then the current was increased to the target current of 45 A to heat and evaporate the sulfur powder. The heating time was 4400 s, and all the sulfur powder was evaporated. (6) Turn off the resistance heating evaporation system, start the substrate holder rotation at a speed of 17 rpm, fill the vacuum chamber with high-purity Ar at a flow rate of 16.1 sccm, and maintain the sputtering gas pressure at 5.0 Pa; (7) Turn on the RF power supply and pre-sputter the target material at a power of 100 W for 5 minutes, then open the substrate baffle and perform formal magnetron reactive sputtering deposition for 15 minutes; (8) Close the substrate baffle, RF power supply and Ar gas, stop the substrate holder from rotating, then fill the vacuum chamber with air to normal pressure, open the vacuum chamber, and remove the CdS film.

[0028] The XRD and transmission spectrum test results of the CdS film prepared in Example 1 are as follows: Figure 2 As shown. Figure 2 It can be seen from a that an obvious diffraction peak is observed at 2θ=26.5°, which corresponds to the (002) crystal plane of hexagonal CdS (PDF#77-2306). The peak is strong and the half-height width is small, about 0.27°, indicating that the crystal quality is good. Figure 2 b shows that the average light transmittance of the film is about 80%; the SEM image of the film is as shown in FIG. Figure 3 As shown in a, the film is continuous, dense and uniform; Figure 4 The EDS result of a shows that the S / Cd molar ratio of the film prepared in Example 1 is 1.20. Example

[0029] This embodiment is basically the same as embodiment 1, except that the sputtering pressure is 3.5 Pa and the argon flow rate is 8.5 sccm. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 2 are shown in FIG. Figure 2 As shown. Figure 2 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is smaller than that in Example 1, which is about 0.17°, indicating that its crystal quality has improved. In addition, a very weak diffraction peak is found at 2θ=54.5°, corresponding to the (004) crystal plane of the CdS hexagonal crystal structure (PDF#77-2306); Figure 2 b shows that the average light transmittance of the film is about 80%; the SEM image of the film is as shown in FIG. Figure 3As shown in b, the film is continuous, dense and uniform, and the film particles are larger than those in Example 1; the S / Cd molar ratio of the film is 1.12. Example

[0030] This embodiment is basically the same as embodiment 2, except that the sputtering pressure is 2.8 Pa and the argon flow rate is 7.1 sccm. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 3 are shown in FIG. Figure 2 As shown. Figure 2 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly smaller than that in Example 2, indicating that its crystallinity has been improved; Figure 2 b It can be seen that the average transmittance of the CdS film is about 80%.

[0031] Comparative Example 1 As a comparative example, the method is basically the same as Example 2, except that the sputtering pressure is 2.0 Pa and the argon flow rate is 3.3 sccm. The XRD and transmission spectrum test results of the film prepared in Comparative Example 1 are shown in FIG. Figure 2 As shown. Figure 2 a As can be seen from the figure, no XRD diffraction peaks of CdS phase appeared, and only the XRD diffraction peaks of Cd (PDF#85-1328) were observed, which appeared at 2θ of 31.9°, 34.7°, 38.4°, and 47.8°, respectively, indicating that the main Cd metal phase was formed; Figure 2 b shows that its transparency is very poor, because the film is mainly composed of Cd metal, which strongly absorbs photons in the entire wavelength range, resulting in very low light transmittance of the film. The SEM image of the film is as follows Figure 3 As shown in c, its surface morphology is completely different from that in Examples 1 and 2, which is related to the fact that the film mainly forms a Cd metal phase; and Figure 4 The EDS results of c confirm that the S element content in the film prepared in Comparative Example 1 is very small, and the S / Cd molar ratio is 0.17, which further confirms that the film is mainly a Cd metal film with a very small CdS content; this is because in step (7) of Comparative Example 1, during the sputtering of the metal target at a lower pressure (2 Pa), more Cd metal atoms will reach the substrate per unit time, but the sulfur powder evaporation conditions are the same as those in Example 2, so most of the metal atoms do not have time to react with the sulfur vapor, and mainly Cd metal phase is formed on the substrate, with very little CdS. Example

[0032] This embodiment is basically the same as embodiment 2, except that the sputtering power is 60 W. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 4 are shown in FIG. Figure 5 As shown. Figure 5It can be seen from a that the CdS film has a hexagonal structure and the half-height width of its strongest peak is larger than that in Example 2, indicating that its crystallinity is reduced; Figure 5 b It can be seen that the average transmittance of the CdS film is about 70%; the S / Cd molar ratio of the film is 2.0. Example

[0033] This embodiment is basically the same as embodiment 2, except that the sputtering power is 150 W. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 5 are shown in FIG. Figure 5 As shown. Figure 5 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly smaller than that in Example 2, indicating that its crystallinity has been improved; Figure 5 b It can be seen that the average transmittance of the CdS film is about 80%; the S / Cd molar ratio of the film is 1.09. Example

[0034] This embodiment is basically the same as embodiment 2, except that the sputtering deposition time is 5 minutes. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 6 are shown in FIG. Figure 6 As shown. Figure 6 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly larger than that in Example 2, indicating that its crystallinity is reduced; Figure 6 b shows that the average transmittance of the CdS film is about 80%; the S / Cd molar ratio of the film is 1.12; the cross-sectional SEM image of the film is as follows Figure 7 As shown in a, the film thickness is about 130 nm. Example

[0035] This embodiment is basically the same as embodiment 2, except that the sputtering deposition time is 60 min. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 7 are shown in FIG. Figure 6 As shown. Figure 6 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly smaller than that in Example 2, indicating that its crystallinity is slightly improved; Figure 6 b shows that the average transmittance of the CdS film is about 80%; the S / Cd molar ratio of the film is 1.03; the cross-sectional SEM image of the film is as follows Figure 7 As shown in FIG. 3 , the thickness of the film is about 1000 nm, which is greater than the thickness of the CdS film prepared in Example 2 ( Figure 7 b, about 190 nm). Example

[0036] This embodiment is basically the same as embodiment 2, except that the mass of evaporated sulfur powder is 100 mg and the heating evaporation time is 1500 s. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 8 are shown in FIG. Figure 8 As shown. Figure 8 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly larger than that in Example 2, indicating that its crystallinity is slightly reduced; Figure 8 b It can be seen that the average light transmittance of the CdS film is about 80%; the S / Cd molar ratio of the film is 1.13. Example

[0037] This embodiment is basically the same as embodiment 2, except that the mass of evaporated sulfur powder is 400 mg and the heating evaporation time is 5000 s. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 9 are shown in FIG. Figure 8 As shown. Figure 8 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly smaller than that in Example 2, indicating that its crystallinity has been improved; Figure 8 b It can be seen that the average transmittance of the CdS film is about 80%; the S / Cd molar ratio of the film is 1.08. Example

[0038] This embodiment is basically the same as embodiment 2, except that the evaporation current is 75A and the evaporation time is 1800s. The XRD and transmission spectrum test results of the CdS film prepared in embodiment 10 are shown in FIG. Figure 9 As shown. Figure 9 It can be seen from a that the CdS film has a hexagonal structure, and the half-height width of its strongest peak is similar to that in Example 2, indicating that its crystallinity is good; Figure 9 b It can be seen that the average transmittance of the CdS film is about 80%; the S / Cd molar ratio of the film is 1.14. Example

[0039] This embodiment is basically the same as embodiment 2, except that the target material used is CdZn alloy and the concentration of Zn doping is 10at.%. The XRD and transmission spectrum test results of the doped CdS film prepared in embodiment 11 are shown in FIG. Figure 10 As shown. Figure 10 It can be seen from a that the doped CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly smaller than that in Example 2, indicating that its crystallinity is slightly improved; Figure 10b It can be seen that the average transmittance of the doped CdS film is slightly lower than 80%. At the same time, it is found that its optical characteristic absorption edge is blue-shifted toward the short-wave direction compared with that in Example 2, indicating that doping has changed the optical properties of the film; the S / (Cd+Zn) molar ratio of the film is 0.99, and the composition has become better compared with that in Example 2; the Zn / (Zn+Cd) molar ratio of the film is 0.11, which is close to the doping concentration of the alloy target used in Example 11. Example

[0040] This embodiment is basically the same as embodiment 2, except that the target material used is CdZn alloy, and the concentration of Zn doping is 30at.%. The XRD and transmission spectrum test results of the doped CdS film prepared in embodiment 12 are shown in FIG. Figure 10 As shown. Figure 10 It can be seen from a that the doped CdS film has a hexagonal structure, and the half-height width of its strongest peak is slightly larger than that in Example 2, indicating that its crystallinity is reduced; Figure 10 b It can be seen that the average transmittance of the doped CdS film is about 80%, and its characteristic absorption edge is further blue-shifted; the S / (Cd+Zn) molar ratio of the film is 0.98; the Zn / (Zn+Cd) molar ratio of the film is 0.36, which deviates from the alloy target composition used in Example 12. This is because in the magnetron sputtering alloy target, there are certain differences in the sputtering yield and rate of the two metal elements Cd and Zn. Example

[0041] This embodiment is basically the same as embodiment 2, except that the target material used is CdZn alloy, and the concentration of doped Zn is 50at.%. The XRD and transmission spectrum test results of the doped CdS film prepared in embodiment 13 are shown in FIG. Figure 10 As shown. Figure 10 It can be seen from a that the doped CdS film has a hexagonal structure, and the half-height width of its strongest peak is larger than that in Example 2, indicating that its crystallinity is reduced; Figure 10 b It can be seen that the average transmittance of the doped CdS film is about 80%, and its characteristic absorption edge ( Figure 10 b) is obviously blue-shifted compared with that in Example 12; the S / (Cd+Zn) molar ratio of the film is 0.94; the Zn / (Zn+Cd) molar ratio of the film is 0.65, which is obviously deviated from the alloy target composition used in Example 13.

[0042] Table 1 Molar ratio of S to Cd in CdS films prepared in Examples 1, 2, 4-10 of the present invention Example No. S / Cd molar ratio Example 1 1.20 Example 2 1.12 Example 4 2.00 Example 5 1.09 Example 6 1.12 Example 7 1.03 Example 8 1.13 Example 9 1.08 Example 10 1.14 Table 2 Molar ratio of elements in Zn-doped CdS films prepared in Examples 11-13 of the present invention Example No. S / (Cd+Zn) molar ratio Zn / (Zn+Cd) molar ratio Example 11 0.99 0.11 Example 12 0.98 0.36 Example 13 0.94 0.65 Combining Examples 1-13 and Comparative Example 1, the following conclusions can be drawn: a CdS thin film is obtained by first evaporating sulfur powder by resistive heating and then reactively depositing a metal target by magnetron sputtering. The formation process is as follows: first, the sulfur powder is heated and evaporated to form sulfur vapor, and then a Cd or CdZn alloy target is formally sputtered. The sputtered metal atoms react with the sulfur vapor in the vacuum chamber to deposit an undoped CdS or doped CdS thin film. The resulting film is a hexagonal phase with good transmittance. The sputtering pressure, sputtering power, sputtering time, evaporated sulfur amount, evaporation current, and doping concentration have varying degrees of influence on the formation, crystal quality, transmittance, and stoichiometric composition of the reactively deposited CdS thin film.

[0043] Combining Examples 1, 2, 3 and Comparative Example 1, the following conclusions can be drawn: sputtering pressure has a major influence on the formation of CdS thin films. When the sputtering pressure is too low, CdS thin films cannot be obtained, and the obtained films are mainly Cd metal. Only by appropriately increasing the sputtering pressure can CdS thin films be obtained.

[0044] Combining Examples 2, 4, and 5, the following conclusions can be drawn: as the sputtering power increases, the crystallinity of the obtained CdS film improves, the S / Cd molar ratio of the CdS film tends to decrease, but there is no lack of sulfur.

[0045] Combining Examples 2, 6, and 7, the following conclusions can be drawn: sputtering time has a significant effect on the thickness of the CdS film. Increasing the sputtering time is beneficial to improving the crystallinity of the CdS film and significantly increasing the film thickness. The S / Cd molar ratio tends to decrease, but there is no lack of sulfur.

[0046] Combining Examples 2, 8, and 9, the following conclusions can be drawn: as the mass of evaporated sulfur powder increases, the crystallinity of the obtained CdS thin film improves, and the stoichiometric composition does not change much.

[0047] Combining Examples 2 and 10, the following conclusions can be drawn: the evaporation current has little effect on the crystallinity, composition, and transmittance of the CdS thin film.

[0048] Combined with Examples 2 and 11-13, the following conclusions can be drawn: Zn doping affects the crystallization quality, composition and optical properties of CdS thin films. When Zn doping is performed at an appropriate concentration, the crystallinity of the CdS thin film is improved, the S / (Cd+Zn) molar ratio becomes better, and the optical characteristic absorption edge blue-shifts. Its optical properties can be adjusted by doping; when the doping amount increases, the crystallinity of the film and the S / (Cd+Zn) molar ratio both tend to decrease.

[0049] In summary, the evaporation combined with sputtering method of the present invention has successfully prepared CdS thin films with high transmittance, good crystallization, and adjustable film thickness, composition, and optical properties at room temperature. The method has the characteristics of low cost, room temperature preparation, no annealing required, and safety. In addition, the method of the present invention is expected to be expanded to the preparation of other metal sulfide compound thin film materials.

[0050] The above description is only an embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, improvements, etc. made by ordinary technicians in this technical field without departing from the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for depositing metal sulfide thin films by magnetron reactive sputtering at room temperature, characterized in that The steps include: (1) Clean the substrate, dry it, and place it on the substrate holder in the vacuum chamber; (2) Installing the single element metal target or alloy target at the corresponding target position in the vacuum chamber; (3) Weigh sulfur powder, place it in a steam boat, and install the steam boat at the corresponding evaporation station in the vacuum chamber; (4) Evacuate the vacuum chamber to a pressure less than 5×10 -3 Pa; (5) Turn on the resistance heating evaporation system to heat and evaporate the sulfur powder; (6) Fill with high-purity argon, turn on the RF power supply, and maintain the substrate at room temperature; before the formal sputtering deposition, pre-sputter the metal target for a time greater than or equal to 5 minutes. After the pre-sputtering is completed, open the substrate baffle and formally sputter the metal target for reactive deposition to obtain a metal sulfide film. The formal sputtering time is 5 minutes to 60 minutes. The power and sputtering pressure of the pre-sputtering and formal sputtering are the same, the power is 60W to 150W, and the sputtering pressure is 2.8Pa to 5Pa.

2. The method according to claim 1, characterized in that In step (1), the substrate material is quartz glass.

3. The method according to claim 1 or 2, characterized in that In step (1), the substrate is cleaned by ultrasonically cleaning the substrate material in deionized water, acetone, and anhydrous ethanol for 10 minutes respectively, and then drying.

4. The method according to claim 1 or 2, characterized in that In step (2), the single element metal target is Cd with a purity of 99.99 wt.%, the alloy target is CdZn alloy, the Zn doping concentrations are 10 at.%, 30 at.%, and 50 at.%, respectively, and the purity of CdZn is 99.99 wt.%. The distance between the target and the substrate is 13 cm.

5. The method according to claim 1 or 2, characterized in that In step (3), the mass of the sulfur powder is 100-400 mg, the purity is 99.5 wt%, the steam boat uses an evaporation molybdenum boat, and the distance between the steam boat and the substrate is 20 cm.

6. The method according to claim 1 or 2, characterized in that In step (5), the substrate baffle is always closed, and the resistance heating evaporation system is turned on to preheat the steam boat and sulfur powder for 30 seconds. After the preheating is completed, the current is increased to the target current for heating and evaporation to evaporate all the sulfur powder in the steam boat; the current for preheating the steam boat and sulfur powder is 30A, and the target current for heating and evaporation is 45A-75A.

7. The method according to claim 1 or 2, characterized in that In step (6), the purity of the high-purity argon filled is 99.999 at.%, and the substrate holder rotation speed is 17 rpm.

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