Facile synthesis of large-area and highly crystalline WS2 film on dielectric surfaces for SERS

A facile fabrication of high-quality and large-area tungsten disulfide (WS2) layers is demonstrated using a thermal decomposition of tetrathiotungstates ((NH4)(2)WS4) with two annealing process. During synthesis, the first annealing step is utilized to achieve lateral epitaxial growth of the WS2 and create seamless and large-area WS2 film. The second annealing step can offer an S-rich and high temperature condition, which is beneficial for the high quality of the WS2 film. Scanning electron microscopy, Raman spectroscopy and atomic force microscopy confirm the presence of large-area and high-quality WS2 film. The crucial role of the S, H-2 and the effect of the temperature during the experiment are also investigated. Furthermore, the potential application of the prepared WS2 as a substrate for Raman enhancement is first discussed using R6G molecules as probe molecule. (C) 2016 Elsevier B.V. All rights reserved.