Growth dynamics of pulsed laser deposited WS2 thin films on different substrates

Abstract

The scaling behavior, as well as growth mechanism of polycrystalline WS2 thin films grown on glass and Si substrates by pulsed laser deposition as a function of the deposition time, has been studied using height–height correlation function using the AFM images. X-ray diffraction measurement confirms the increase in crystallinity of the WS2 thin film on both the substrates. The WS2 films deposited onto Si substrate showed high rate of roughening or interface width (w) and a rapid increase in island size or correlation length (ξ) of WS2 nanoclusters in comparison to the films deposited onto glass substrate. The WS2 films grown on glass substrate evolved following the nonlinear stochastic deposition equation, however, WS2 films on Si substrate follow a linear growth model. The difference in surface smoothness, thermal conductivity and sticking coefficient of the two substrates causes different growth patterns of WS2 films onto the substrates. The growth of the WS2 films on the two different substrates evolved differently which has been realized more conveniently by schematically analyzing the behavior of the evolution of ξ and w with deposition time, t. The high roughness of the films deposited onto oxidized Si provides a large surface area, which will be useful for electro-catalysis applications.