Oxidation limited thermal boundary conductance at metal-graphene interface

Abstract

Thermal management is a substantial challenge in high-power-density micro- and nanoelectronic devices, and the thermal resistance at the interfaces in these devices is a major bottleneck to heat removal. Graphene has emerged as a potential candidate for next generation nanoelectronic devices because of its exceptional transport properties; however, the thermal interaction between graphene and other materials such as metals is not completely understood. Here we report thermal boundary conductance (TBC) measurements at metal-graphene-metal (M-G-M) interfaces at room temperature using time-domain thermoreflectance. The metals used in this study represent two classes based on the type of bonding formed with graphene. Ti and Ni form chemisorbed interfaces (strong bonding) with graphene and high TBC is expected while Au forms physisorbed interfaces (weak bonding). The measured TBC at M-G-M interfaces showed little variation (∼30 MW/m2-K) and was similar to metal-graphene-SiO2 interfaces, contrary to high TBC predicted by previous simulation studies. X-ray photoelectron spectroscopy was used to estimate thickness of the native oxide layer of bottom Ti (2.8 nm) and Ni (2.5 nm) layers. The conductance of these thin native oxide layer was much greater than the overall TBC but prevented formation of chemisorbed interfaces between graphene and metal for Ti and Ni cases leading to significantly lower TBC and highlighting an important consideration for practical applications.