Tungsten Trioxide Thin Films Prepared by Sputtering Method
Synthetic nano tungsten trioxide or thin film methods are usually gas phase method, solid phase method, liquid phase method. Sputtering method is a preparation of nano tungsten trioxide film gas phase preparation method.
The most widely used sputtering method is magnetron sputtering. Some foreign scholars use metal W as a target, and use a mixed gas of Ar and O2 to prepare a WO3 thin film which is more gas-sensitive to NOx by magnetron sputtering. In addition, there are scholars using DC magnetron sputtering device, the target is 99.95% W, in a vacuum degree of 2 × 10-6mbar reaction chamber, Ar (50%) - O2 (50%) the mixed gas is subjected to direct current radio frequency excitation and discharge to deposit the WO3 thinly on the substrate to obtain a WO3 thin film. The electrochromic properties are also studied.
Compared with other coating methods, the sputtering coating method has the following advantages: (1) Any substance can be spattered, especially high melting point, low vapor pressure element and compound. (2) The adhesion between the sputtering film and the substrate is good. High energy particles are deposited on the substrate for energy conversion, producing higher heat energy and enhancing the adhesion between the sputtering atom and the substrate. (3) The sputtering density is high, the pinholes are few, and the purity of the films is high, because there is no such phenomenon as the crucible pollution in the process of sputtering. (4) The thickness of the film is controllable and the reproducibility is good. In addition, a thin film with uniform thickness can be obtained on a large area by the sputtering coating.
In recent years, radio frequency sputtering and magnetron sputtering technology have made great progress in China, and have made some progress in improving sputtering speed and reducing substrate temperature. Sputtering method has also become the main method of preparation of nano tungsten trioxide film, but it needs to be explained that the equipment price of sputtering method is more expensive and the investment in the early stage is larger.