Synthesis of type-I textured tungsten disulfide thin films on quartz substrate

Tungsten disulfide (WS2) films were obtained by solid state reaction of spray deposited WO3 with gaseous sulfur i.e. solid gas phase reaction (SGP). The XRD and SEM studies revealed the formation of WS2 thin films on quartz substrate with a mixed type-I and type-II texture. The WS2 thin films prepared with a controlled heating/cooling rate of 323 K/h. during the sulfurization were free from cracks while those prepared with higher heating/cooling rate during the sulfurization suffer from cracks. The former WS2 thin film comprises well defined hexagonal crystallites with larger size (2 μm) and thickness. The complete conversion of WO3 into WS2 was observed when sulfurization carried out in evacuated quartz ampoule containing sulfur. A low oxygen and carbon content was observed in XPS spectrum due to air exposure of the sample which is removed by in-situ Ar cleaning. XPS and EDS studies showed that the films are stoichiometric.