Impact of Nanoscale Roughness on Heat Transport across the Solid-Solid Interface

The performance of 1D nano/microbeam-based devices greatly relies on heat dissipation to substrates. The surface roughness plays a key role in interfacial heat transport while this issue is seldom investigated due to the difficulty in quantitative determination of thermal contact resistance (TCR) at nanoscale. Here, the impact of interfacial roughness on heat transport at solid-solid interface by taking VO2 microbeam on Si substrate (VO2/Si) as a prototype is investigated. With the increased interface roughness from atomic fluctuation to approximate to 100 nm, it is found that an unusual uncertainty emerges in thermal interface transport along with the dramatical increase in TCR with two orders of magnitudes. Besides, a single-layer graphene is inserted into VO2/Si interface as thermal interface material to study its performance under interface roughness. The inserted graphene not only substantially reduces the TCR but also reduces the uncertainty of thermal interface transport. This enhancement is even remarkable at rougher interface. Microscopic characterization and molecular dynamics simulation suggest that suspended condition and high heat conductivity of graphene on rough surface are responsible for the above effects. This work provides the quantitative evaluation of TCR and contributes to the in-depth understanding on heat transport at imperfect interface.