Thermal properties ofa−Si:Hat low temperatures

The specific heat and thermal conductivity of bulk samples of $a-\mathrm{S}\mathrm{i}:\mathrm{H}$ have been measured in the temperature range 0.1-5 K. A quasilinear temperature dependence of the specific heat and a $T^2$ thermal conductivity indicates a density of two-level tunneling systems very similar to that in fused silica. A flow of heat from the sample has been observed at low temperatures, with a decay extending over a period of days.