LARGE-SCALE SYNTHESIS OF HOMOGENEOUS WS2 FILMS BY PHYSICAL VAPOR DEPOSITION

Abstract

TMDs are semiconductors, unlike graphene, and have a direct bandgap when converted from bulk to thin film. This property makes TMDs an ideal material for optoelectronic and photovoltaic applications due to their strong optical absorption and photoluminescence effect. The WS2, a popular TMD, has unique properties such as low friction coefficient, high thermal stability, and good electrical conductivity, and a bandgap energy of approximately 1.2 eV and 2.2 eV for indirect and direct behaviors. The article also discusses various methods for synthesizing WS2, including chemical vapor deposition (CVD), physical vapor deposition (PVD), hydrothermal synthesis, and solvothermal synthesis. PVD is a scalable method for producing large-area films and coatings with high quality, but the difficulty of controlling the sulfur or selenium sources in this method leads to the need for optimizing growth parameters for large-scale and high-quality WS2 film synthesis. The study reports the successful growth of large-scale and homogeneous WS2 films on a glass substrate using PVD and optimized substrate temperature. The results of this study provide valuable information for the advancement of WS2 film growth techniques and the development of WS2-based semiconductor technologies, such as transistors, diodes, photodetectors, and solar cells.