Benjamin Robinson 1
, Oleg Kolosov 1 1
, Lancaster University, Lancaster United Kingdom
Nanoscale solid-solid contact defines a wealth of materials behaviour from the friction in micro- and nanoelectromechanical systems to electrical and thermal conductivity in modern electronic devices. For modern, ultra-high integration processor chips and power electronic devices one of most essential, but thus far most challenging, aspects is the heat transport in nanoscale sized interfaces. The Highest spatial resolution to date, achieved via nanoscale probes in scanning thermal microscopy (SThM)1, is often devalued by the poorly defined nature of the nanoscale contacts2. However truly uunderstanding the thermal properties of such nanoscale junctions is of fundamental importance for the development of next generation nanodevices, where ballistic transport is expected to dominate bulk-like diffusive and convective transport and may, indeed, be quantised.
Here we show that simultaneous measurement of shear forces and heat flow between the probe and the studied material elucidates the key parameters of solid-solid contact. Our analysis indicates the ballistic nature of heat transport via nanoscale contacts in such a system. Furthermore, in analogy to the Wiedemann-Franz law linking electrical and thermal conductivity in metals3, we show that a generalised relation exists linking shear forces and thermal resistance in nanoscale contacts via fundamental material properties such as heat capacity and heat carrier group velocity. These factors, together with the clearly observed anti-correlation of the thermal resistance and shear forces, demonstrate a quantitative approach for the experimental characterisation of thermal transport in nanoscale junctions.
1. Gomès, S., Assy, A. & Chapuis, P.-O. Scanning thermal microscopy: A review. physica status solidi (a) 212, 477-494 (2015).
2. Gotsmann, B. & Lantz, M. A. Quantized thermal transport across contacts of rough surfaces. Nat Mater 12, 59-65 (2013).
3. Franz, R. & Wiedemann, G. Ueber die Wärme-Leitungsfähigkeit der Metalle. Annalen der Physik 165, 497-531 (1853)