Thermal conductivity ofa-Si:H thin films

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 μm is determined in the temperature range 80–400 K using an extension of the 3ω measurement technique. The reliability of the method is demonstrated on 1-μm-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.