Electronic interfacial thermal conductance between metal nano-films in sub-picosecond non-equilibrium transport process

Abstract

Interfaces play a critical role in nanoscale thermal transport, and understanding thermal transport mechanisms across metal/metal interfaces at the non-equilibrium states is urgently needed for highly integrated electronic structures or devices. In this work, the electronic interfacial thermal conductance hee of two metal interfaces, Au/Pt and Au/Al, was measured by time domain thermoreflectance (TDTR) at the non-equilibrium states and an extended two-temperature model was applied to well describe the interactions of electrons between the metal films. For the Au/Pt structure, the measured hee is 4.4 ± 1.8 GWm−2K−1, which is consistent with the predicted value by the electronic diffuse mismatch model (DMM). While for the Au/Al structure, the measured hee (0.13±0.05 GWm−2K−1) is an order of magnitude smaller than that of Au/Pt and the predicted value of the electronic DMM. The results indicate that even the extremely thin oxide layer at the Au/Al interface can significantly hinder the electron thermal transport across the metal interface. Overall, our findings contribute to revealing the non-equilibrium interfacial thermal transport mechanisms and pave the way for designing the highly integrated electronic devices.