Temperature dependent Raman investigations of few-layered WS2 nanosheets. (August 2019)

• Record Type: Journal Article
• Authors: Sinha, Sneha; Sathe, Vasant; Arora, Sunil K.
• Is Part Of: Solid state communications. Volume 298(2019)
• Publication Date: 2019-08
• Subjects: A. Transition metal dichalcogenides -- B. Liquid phase exfoliation -- D. Multiphonon scattering -- E. Raman spectroscopy; Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2019.04.013
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: We studied the temperature dependent phononic response of few-layered liquid phase exfoliated WS2 nanosheets using Raman spectroscopy over a wide temperature range from 80 to 600 K. We find that the E 1 2g (in-plane) and A1g (out-of plane) modes follow a systematic red shift with increase in temperature and exhibits weak non-linear temperature dependence in the temperature range of 350–600 K. The first-order temperature coefficients are found to be −0.0111 cm −1 K −1 and -0.0103 cm −1 K −1 for E 1 2g and A1g modes, respectively. From our analysis which is based on a semi-quantitative model, we find that at higher temperatures the non-linear temperature dependence of E 1 2g and A1g modes primarily originates from the an-harmonic effects of three-phonon process as a consequence of creation of S vacancies in the WS2 nanosheets. The thermal expansion contribution is mainly dominant in low temperature region. Highlights: The in-plane and out-of plane Raman modes of WS2 nanosheets shifts non-linearly with temperature. A quantitative analysis is provided to understand non-linear temperature dependency of phononic modes of WS2 nanosheets. The non-linear temperature dependence of phononic modes primarily originates from the multi-phonon scattering process.