Negative Thermal Expansion Coefficient of Graphene Measured by Raman Spectroscopy

TL;DR

This study measures the negative thermal expansion coefficient of single-layer graphene across 200-400 K using Raman spectroscopy, highlighting the importance of strain effects due to TEC mismatch with substrates.

Contribution

It provides the first detailed temperature-dependent measurement of graphene's TEC, emphasizing the role of substrate-induced strain in its physical properties.

Findings

Graphene's TEC remains negative from 200 to 400 K.

Room temperature TEC of graphene is approximately -8.0x10^{-6} K^{-1}.

Strain from TEC mismatch significantly influences graphene's properties.

Abstract

The thermal expansion coefficient (TEC) of single-layer graphene is estimated with temperature-dependent Raman spectroscopy in the temperature range between 200 and 400 K. It is found to be strongly dependent on temperature but remains negative in the whole temperature range, with a room temperature value of -8.0x10^{-6} K^{-1}. The strain caused by the TEC mismatch between graphene and the substrate plays a crucial role in determining the physical properties of graphene, and hence its effect must be accounted for in the interpretation of experimental data taken at cryogenic or elevated temperatures.