This talk will cover new frontier research on phonon and hot carrier transport probing based on Raman scattering, a technology traditionally widely used for structure analysis. The team has developed a new technique, termed energy transport-state resolved Raman (ET-Raman). It is capable of probing physical transport processes down to nanosecond and picosecond scales and is able to simultaneously characterize the conjugated phonon transport in the in-plane and cross-plane directions and hot carriers diffusion in the in-plane direction. 2D materials down to monolayer thickness have been investigated for studying the structure effect on the in-plane thermal conductivity, interface thermal resistance, hot carrier diffusion coefficient/ mobility, and electron-hole radiative recombination. This provides an advanced phonon and electron transport study of virgin 2D materials. Also for the first time, the team has distinguished the temperatures of optical and acoustic phonons in 2D materials under photon excitation and characterized the energy coupling factor between them. Solving this decade-long problem presents a significant advance in measuring the intrinsic thermal conductivity and interface thermal conductance of 2D materials and will enable advanced material structure design toward thermal control and optimization.
