High-pressure photoluminescence results were reported for bulk material or thin films which contained 1018 to 1019/cm3 of P or As acceptors. A cryogenic (4 to 300K) diamond anvil cell was used at pressures of up to 55kbar. Attention was focused upon the deep photoluminescence bands in the red and green regions of the visible spectrum. The red emission bands (1atm peaks at about 600nm in P-doped material and at about 700nm in As-doped material) were thought to arise from C3v-distorted acceptor sites. With increasing pressure, the peak energies of all of the deep bands approached, but did not cross, the ZnSe band gap. The average deformation potential of the valence edge, relative to the P or As deep levels attributed to C3v sites, was -1.2eV. The negative sign was confirmed by thermal quenching data for various pressures in P-doped material. The results implied that, with increasing pressure, the valence edge shifted to higher energy; thus causing deep acceptor states to become less stable. A marked transfer of oscillator strength from red to green emission, and several deep bands, were observed under pressure. However, because the shallow acceptor-bound exciton photoluminescence was not enhanced, it was concluded that a deep-to-shallow transition had not occurred within the pressure range which was studied.

M.M.Li, D.J.Strachan, T.M.Ritter, M.Tamargo, B.A.Weinstein: Physical Review B, 1994, 50[7], 4385-90