Specific Heat of Amorphous Germanium at Very Low Temperatures

Abstract
A specific-heat study of a tetrahedrally bonded amorphous semiconductor at very low temperatures (0.08-2.5 K) is reported. Through an investigation of as-evaporated and annealed amorphous Ge films it can be shown that the contribution by low-energy excitations considered akin to the amorphous state is at least six times smaller than in vitreous silica. The specific heat observed below 1 K is mainly attributed to localized unpaired electronic states ("dangling bonds") situated in clusters.