Non-Linear behavior of Raman Linewidth of 1-3 Layer WSe2

TL;DR

This study investigates how temperature affects the Raman linewidth (FWHM) of WSe2 with different layer thicknesses, revealing distinct non-linear behaviors and modeling them with theoretical approaches.

Contribution

It provides the first detailed analysis of temperature-dependent FWHM trends in 1-3 layer WSe2 and applies a Klemens model to explain non-linear behavior.

Findings

1L WSe2 shows a parabolic FWHM trend with temperature.

2L WSe2 exhibits a linear FWHM increase with temperature.

3L WSe2 FWHM behavior fits a Klemens model, indicating non-linear effects.

Abstract

In recent years, Raman spectroscopy of two-dimensional (2D) materials has been conducted. However, only a small portion of those studies note the full width half maximum (FWHM) of these 2D materials. FWHM is an indicator of phonon dispersions in 2D materials. In addition, it is a critical parameter that can denote the quality of the given 2D material, which is directly related to its engineering performance for manufactured devices. In this study, we analyze the effect that temperature has on the FWHM of the E2g1 mode for WSe2. We also analyze this temperature dependent trend for WSe2 with different thicknesses: monolayer (1L), bilayer (2L), and triple-layer (3L). The results show a different trend associated with each thickness on temperature dependence analysis for WSe2. The 1L WSe2 shows a parabolic trend with increasing temperature. Meanwhile, the 2L shows a steady linear trend with increasing temperature. On the other hand, FWHM for 3L WSe2 can be fitted by a simplified Klemens model, which explains its non-linear behavior.