SPECTRAL RESPONSE OF PHOTOCURRENT IN GLASSY AND CRYSTALLINE AG-RICH AG-AS(GE)-S COMPOUNDS

Photocurrent in Ag-As(Ge)-S glasses of 16-45 at% Ag and the related cr ystals sandwiched between Au films has been measured to reveal the ele ctronic band structure of Ag-rich glasses. The intensity was found to increase exponentially with increasing Ag content. The peak energy of the spectral response was greater by 0.5 eV than the optical gap for a ll the glasses. The results suggest that the Ag-S bonding states in Ag -rich glasses form the valence band, and the peak of photocurrent spec tra lies at around the mobility edge of the valence band.