Temperature-dependent Phonon Shifts in Monolayer MoS2

TL;DR

This study investigates how temperature affects phonon frequency shifts in monolayer MoS2, revealing a larger shift in the A1g mode compared to E2g, contrasting bulk behavior, due to anharmonic ionic interactions.

Contribution

It provides new experimental and computational insights into temperature-dependent phonon shifts in monolayer MoS2, highlighting differences from bulk material behavior.

Findings

A1g mode exhibits a larger red-shift than E2g with increasing temperature.

Temperature dependence is driven by anharmonic ionic interactions.

Contrasts with previous bulk MoS2 phonon shift observations.

Abstract

We present a combined experimental and computational study of two-dimensional molybdenum disulfde (MoS2) and the effect of temperature on the frequency shifts of the Raman-active E2g and A1g modes in the monolayer. While both peaks show an expected red-shift with increasing temperature, the frequency shift is larger for the A1g more than for the E2g mode. This is in contrast to previously reported bulk behavior, in which the E2g mode shows a larger frequency shift with temperature. The temperature dependence of these phonon shifts is attributed to the anharmonic contributions to the ionic interaction potential in the two-dimensional system.