Characterization of thermal boundary conductance of 2D–3D van der Waals interface using wideband transducerless frequency-domain thermoreflectance

Thermal boundary conductance (TBC) of van der Waals (vdW) interfaces plays a crucial role in thermal dissipation in devices based on two-dimensional (2D) materials, affecting both device performance and longevity. Nevertheless, accurate, rapid, and in situ characterization of the TBC of such interfaces has long posed a substantial challenge in the field of thermal metrology, primarily due to the inherent limitations of existing techniques. In this paper, we demonstrate a wideband transducerless frequency-domain thermoreflectance (FDTR) by modifying the conventional surface heating model and fitting the optical absorption depth with the model. Our improved strategy is comprehensively analyzed by comparing its sensitivity and uncertainty with conventional FDTR. We found that removing the transducer significantly increases sensitivity to TBC, and using a wideband frequency range allows us to simultaneously obtain TBC and the optical absorption depth. We performed this methodology in the TBC measurement between MoS2 and various substrates including GaN, SiC, GaAs, Si, and SiO2. Our experiment results suggest that the vdW interaction could restrict the value of TBC to a low range in MoS2-3D structure regardless of the substrate materials, which provides crucial insights into heat transfer at 2D material interfaces.