Thermal conductivity of<i>a</i>-Si:H thin films

Abstract

The thermal conductivity of sputtered a-Si:H thin films for a hydrogen content of 1--20 % and a film thickness of 0.2--1.5 \ensuremath{\mu}m is determined in the temperature range 80--400 K using an extension of the 3\ensuremath{\omega} measurement technique. The reliability of the method is demonstrated on 1-\ensuremath{\mu}m-thick a-${\mathrm{SiO}}_{2}$ thermally grown on Si. Scattering of phonons at the interface between the a-Si:H film and the substrate places a simple upper limit on the heat transport by long-wavelength phonons and facilitates the comparison of the experimental data to recent numerical solutions of a Kubo formula using harmonic vibrations.