Spatially mapping the thermal conductivity of graphene by an opto-thermal method

TL;DR

This paper introduces a novel opto-thermal method combining confocal Raman thermometry and finite-element modeling to map the spatial variation of thermal conductivity in suspended graphene, enabling detailed thermal analysis at the nanoscale.

Contribution

The paper presents a new spatially-resolved technique for measuring thermal conductivity in graphene, addressing limitations of average-based methods.

Findings

Successfully mapped thermal conductivity of pristine and irradiated graphene

Demonstrated method's applicability to layered materials

Enabled insights into local thermal variations

Abstract

Mapping the thermal transport properties of materials at the nanoscale is of critical importance for optimizing heat conduction in nanoscale devices. Several methods to determine the thermal conductivity of materials have been developed, most of them yielding an average value across the sample, thereby disregarding the role of local variations. Here, we present a method for the spatially-resolved assessment of the thermal conductivity of suspended graphene by using a combination of confocal Raman thermometry and a finite-element calculations-based fitting procedure. We demonstrate the working principle of our method by extracting the two-dimensional thermal conductivity map of one pristine suspended single-layer graphene sheet and one irradiated using helium ions. Our method paves the way for spatially resolving the thermal conductivity of other types of layered materials. This is particularly relevant for the design and engineering of nanoscale thermal circuits (e.g. thermal diodes).