Raman laser self-heating technique for thermal characterization of two-dimensional materials.

Abstract

Accurate thermal conductivity characterization is essential for understanding heat transport mechanisms and optimizing thermal management in emerging low-dimensional materials. However, the determination of thermal conductivity components along different in-plane directions remains experimentally challenging and often requires specialized measurement configurations or complex thermal modeling. Here, we present a Raman laser self-heating technique capable of extracting in-plane thermal conductivities along multiple in-plane directions within a single measurement platform. In this approach, a focused Raman laser serves as a localized non-contact heating source, while the resulting steady-state thermal response is monitored through the integrated thermal sensing islands. A finite-element heat-transfer model is further established based on the actual device geometry, and the thermal conductivities are subsequently determined through inverse analysis using a particle swarm optimization algorithm. The proposed technique is validated using silicon nitride (SiNx) thin films, yielding thermal conductivity values within 5% of those measured by the suspended thermal bridge method. The Raman laser self-heating technique provides a practical and versatile approach for thermophysical property characterization of thin-film materials and can be readily extended to systems exhibiting anisotropic thermal transport.