Raman Thermometry for Thermal Transport: Principles, Progress and Prospects Across Low‐Dimensional Materials and Devices

ABSTRACT Raman thermometry is widely used to determine thermal‐transport properties from atomically thin membranes to active device regions. Raman‐active phonon modes change predictably with temperature, enabling a focused laser to act as both heater and thermometer. Measurements of the power‐, position‐ or frequency‐dependent Raman response, interpreted with an appropriate heat‐transfer model, can provide in‐plane thermal conductivity and, in selected geometries, interfacial thermal conductance without electrical contacts. Since the first optothermal measurement of suspended monolayer graphene in 2008, the method has been applied to graphene and related carbon materials, transition‐metal dichalcogenides, hexagonal boron nitride, semiconductor nanowires, wide‐bandgap devices and thermoelectric films. Two‐laser, frequency‐domain, transient, Stokes/anti‐Stokes and scanning implementations have extended the technique to supported and device‐integrated specimens. This review examines the physical basis, experimental configurations, heat‐transfer models, results for representative materials and main sources of uncertainty. Particular attention is given to absorptance, beam size, substrate heat leakage, thermomechanical stress and nonequilibrium phonon populations. We conclude with practical guidance on method selection, model validity and uncertainty reporting.