Growth dynamics of pulsed laser deposited WS 2 thin films on different substrates
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Growth dynamics of pulsed laser deposited WS2 thin films on different substrates Gobinda Pradhan1 · Partha P. Dey1 · Ashwini K. Sharma1 Received: 13 January 2020 / Accepted: 18 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
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 W S2 thin film on both the substrates. The W S2 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 W S2 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 W S2 films onto the substrates. The growth of the W S2 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. Keywords WS2 thin films · Pulsed laser deposition · Growth dynamics · Height-height correlation function
1 Introduction Layered transition metal dichalcogenide (TMDC) materials have emerged as a class of two-dimensional (2D) materials with excellent electronic and optical properties [1–3]. Among them, W S2 has drawn tremendous attention due to its attractive properties like thickness dependent bandgap of 1.2 (indirect) to 1.9 (direct) eV, high electron mobility, high electronic on–off switching ratio, efficient photo responsibility, etc. [4–6]. In the last few years, pulsed laser deposited monolayer to multilayered as well as bulk-like WS2 films demonstrated their efficient uses as photodetector, catalyst and other advanced electronics and optoelectronic devices [7–9]. Surface morphology of a thin film does regulate many of the physical and chemical properties which have a sharp impact on the device performance of the respective films. The growth dynamics of thin films represented by scaling theory is a useful tool to explain the evolution of the surface * Ashwini K. Sharma [email protected] 1
Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
morphology of thin films and to formulate theoretical models of growth modes for different organic and inorganic materials [10–13]. So the understanding of the growth dynamics of the deposited thin films is important to develop an optimized thin film for effici
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