Experimental investigation of nanoscale thermal transport in hotspots at cryogenic temperatures

A scaling study of "localized heating effect" or ballistic phonon transport at cryogenic temperature in crystalline silicon is reported using electrical Joule heating and thermometry of patterned platinum nanoheaters. The thermal resistances of nanoheaters with width ranging from 100 nm up to 5000 nm were measured. The experimental results were processed and analyzed using a very simple thermal resistance model, which must be eventually improved and perfected using simultaneous three-dimensional electrical and heat transfer numerical simulations. However, the preliminary results revealed several important trends indicating the prevalence of localized heating or sub-continuum transport phenomena in the vicinity of a hotspot at low temperatures.