The measurement of annealing cycle effect of Si-Ge-Au amorphous thin film with anomalously large thermoelectric power by using photoacoustic spectroscopy

Photoacoustic spectra of the Si-Ge-Au amorphous superlattice thin film have been measured as functions of annealing cycles. The Si-Ge-Au amorphous superlattice thin film was prepared by the alternating deposition of Si and heavily Au-doped G1e in ultrahigh vacuum. The Si-Ge-Au amorphous thin films show the anomalously high thermoelectric properties such as nondimensional figure of merit ZT similar to 10(3). All prepared samples have intended artificial interval as deposited, but the superlattice structure is destroyed by diffusion even at 500 K with 15 min. annealing. Even after degradation of the superlattice structure, thermoelectric properties change slowly with repeated annealing cycles. Although there are no apparent differences in X-ray diffraction profiles for the amorphous thin film in this region of annealing cycles, we have successfully detected the apparent differences in photoacoustic spectra as a function of annealing cycle.