Thermal conductance at nanoscale amorphous boron nitride/metal interfaces

Abstract

To combat the ever-increasing challenge of thermal management in nanoelectronic devices and reduce the risk of overheating during operation, material interfaces near the active region of a device must be designed for efficient thermal transport. In this study, metal contacts on amorphous boron nitride (a-BN) thin films, a promising dielectric material in two-dimensional systems, are evaluated for the relative thermal transport efficiency. Metals with small atomic masses and high Debye temperatures, aluminum and titanium, reveal as much as a six times improvement in interface thermal conductance, as measured by time domain thermoreflectance, compared to metals of larger atomic masses and low Debye temperatures such as gold and tantalum. The interface transport between a-BN and higher Debye temperature metals prove to depend on the growth conditions, and good initial film wettability was crucial for ensuring a quality metal contact. Interfacial bonding was evaluated by x-ray photoelectronic spectroscopy and the impact on a-BN chemistry and oxidation potential contributed to the understanding of phonon transport across the interface. The study described herein reinforces the crucial requirement to design effective thermal contacts in high-power electronic devices where Joule heating is a concern.