Impact of roughness on heat conduction involving nanocontacts

TL;DR

This study examines how surface roughness affects heat transfer at nanoscale contacts using scanning thermal microscopy, revealing significant reductions in thermal conductance influenced by surface features and probe types.

Contribution

It provides new insights into the relationship between surface roughness, contact mechanics, and heat conduction at the nanoscale, including effects of multi-contact and ballistic conduction.

Findings

Thermal conductance can decrease by up to 90% due to roughness.

Surface roughness significantly impacts nanoscale heat transfer.

Limits of contact techniques for thermal measurements are discussed.

Abstract

The impact of surface roughness on conductive heat transfer across nanoscale contacts is investigated by means of scanning thermal microscopy. Silicon surfaces with out-of-plane rms roughness of ~0, 0.5, 4, 7 and 11 nm are scanned both under air and vacuum conditions. Three types of resistive SThM probes spanning curvature radii over orders of magnitude are used. A correlation between thermal conductance and adhesion force is highlighted. In comparison with a flat surface, the contact thermal conductance can decrease as much as 90% for a microprobe and by about 50% for probes with curvature radius lower than 50 nm. The effects of multi-contact and ballistic heat conduction are discussed. Limits of contact techniques for thermal conductivity characterization are also discussed.