Thermal Conductivity of Amorphous Si at Low Temperatures

Measurements of thermal conductivity of amorphous Si films from 2 to 50 K are presented. The qualitative and quantitative behaviour is similar to thermal conductivity of other amorphous dielectrics. The temperature range of the plateau of λ( T ) correlates with the maximum T m = 30 K of the function c / T 3 ( T ). An analysis of the effective free path of phonons in dependence on the reduced temperature T /θ D results in a remarkable coincidence for amorphous As, Se, Si, Ge, and SiO 2 , GeO 2 in the plateau range. This fact leads to a restriction of hypotheses for explanation of the plateau of thermal conductivity at amorphous materials.