The effects of pressure upon optical transitions, in the photoluminescence spectra, which involved defects were studied. In the case of AgGaS2, the results which were obtained for samples that were doped with Cd or Au were compared with those for unintentionally doped samples. It was found that, in both compounds, there occurred transitions whose pressure coefficients were larger than that of the band-gap. These transitions were deduced to involve deep acceptors. It was suggested that, in such chalcopyrite semiconductors, the valence-band edge could be less pressure-dependent than were deep acceptors. This was because of p-d hybridization of the valence-band wave-functions.

I.H.Choi, P.Y.Yu: Physical Review B, 1997, 55[15], 9642-8