Simultaneous measurement of anisotropic thermal conductivity and thermal boundary conductance of 2-dimensional materials

TL;DR

This paper introduces a novel magneto-optical Kerr effect-based method for simultaneous measurement of in-plane and cross-plane thermal conductivities and boundary conductance in 2D materials, overcoming previous limitations.

Contribution

It presents a new non-suspended, supported sample technique for quantitative thermal characterization of 2D materials, including anisotropic properties, using a magnetic layer as heater and thermometer.

Findings

Measured thermal conductivities of graphene, h-BN, MoS2, and MoSe2.

Demonstrated the method's ability to resolve anisotropic heat transport.

Provided insights relevant for thermal management in 2D material-based devices.

Abstract

The rapidly increasing number of 2-dimensional (2D) materials that have been isolated or synthesized provides an enormous opportunity to realize new device functionalities. Whereas their optical and electrical characterization have been more readily reported, quantitative thermal characterization is more challenging due to the difficulties with localizing heat flow. Optical pump-probe techniques that are well-established for the study of bulk materials or thin-films have limited sensitivity to in-plane heat transport, and the characterization of the thermal anisotropy that is common in 2D materials is therefore challenging. Here we present a new approach to quantify the thermal properties based on the magneto-optical Kerr effect that yields quantitative insight into cross-plane and in-plane heat transport. The use of a very thin magnetic material as heater/thermometer increases in-plane thermal gradients without complicating the data analysis in spite of the layer being optically semi-transparent. The approach has the added benefit that it does not require the sample to be suspended, providing insight of thermal transport in supported, device-like environments. We apply this approach to measure the thermal properties of a range of 2D materials which are of interest for device applications, including single layer graphene, few-layer h-BN, single and few layer MoS2, and bulk MoSe2 crystal. The measured thermal properties will have important implications for thermal management in device applications.