Manipulating electron and phonon flow across interfaces using structural randomness

Understanding electron and phonon transport across interfaces is of great significance for designing efficient solid-state devices such as transistors, laser diodes and thermoelectric energy converters. Interface roughness is a common type of randomness in heterostructures, which strongly affects electron and phonon transport across interfaces. We find that atomically rough interfaces can scatter short-wavelength electrons and assist the transmission between mismatched valleys. The contact resistance is reduced by over an order of magnitude. Our study provides new insights on the conventional wisdom to improve the interfacial transport using graded interfaces. We also use the atomistic Green's function to simulate phonon transport across rough interfaces to show that the basic assumption that phonons lose memories in the often-used diffuse phonon scattering model is questionable. With a parallel treatment of electron and phonon transport, our study points to pathways of simultaneous manipulation of their flow across interfaces.