Ultrahigh thermal conductance of the point contact between amorphous nanowires

Abstract

Amorphous interfaces/contacts are ubiquitous in numerous micro/nanoelectronic devices and functional composite materials. Traditionally, the thermal resistance of interfaces/contacts was believed to be the primary impediment to heat transport. However, in this study, through measuring thermal resistance between crystalline-amorphous core-shell Ge nanowires, we unveil an ultrahigh thermal conductance across the point contact between the amorphous shell of Ge nanowires with a room-temperature value of 892 MW/m2-K. This value surpasses the typical values observed in point contacts between crystalline nanowires/nanoribbons by one to three orders of magnitude and even exceeds that of epitaxial interfaces between well-lattice-matched materials. Molecular and lattice dynamic simulations further reveal that the observed ultrahigh thermal conductance is attributed to the broadened vibrational bandwidths within the amorphous contact, which facilitates the redistribution of phonon energy into a state conductive to more effective interfacial energy transmission, leading to an enhanced overlap of phonon modes and, consequently, a heightened thermal conductance.