Effects of DC sputtering power and rapid thermal processing temperature on tungsten disulfide (WS2) thin films

Abstract

For the direct formation of two-dimensional (2D) tungsten disulfide (WS2) thin films with higher productivity and lower process temperature than conventional chemical vapor deposition (CVD), WS2 thin films were deposited on a sapphire glass substrate by direct current (DC) sputtering and subsequent rapid thermal processing (RTP). From the optical investigation by atomic force microscopy (AFM), it was possible to stable surface and observe more improvements at higher RTP temperatures irrespective of sputtering power. Hall measurements showed higher resistivity and lower carrier density at higher DC sputtering power in spite of the constant carrier mobility. Raman spectrum results showed lateral vibration of tungsten and sulfur atoms at temperatures above 700 degrees C. The directly formed WS2 thin films showed the improvements in structural and electrical characteristics as a semiconductor layer.