Abstract
We have already reported the extremely high thermoelectric properties of Si–Ge–Au amorphous thin films. The thermoelectric properties of such films change slowly during annealing cycles. In this paper, we describe the absorption spectra of the films by using photoacoustic spectroscopy (PAS) to clarify the change mechanism of these thermoelectric properties. Si–Ge–Au amorphous thin films were prepared by the alternate deposition of a non doped Si layer and a heavily Au doped Ge layer. The peak positions of the absorption spectra shift in a complex way with annealing, where the thermoelectric properties change. In these annealing cycles, we assume three stages to explain the mechanism of the change in the thermoelectric properties: the collapse of the superlattice, compositional diffusion and the termination of recrystallization at 673 K. We conclude that the change in the thermoelectric properties is explained by these three stages.