Time-Decay Characteristics of a Deep-Donor-Shallow-Acceptor Pair Band in Gallium Phosphide

Abstract

Characteristics of the photoluminescent time decay of a red band at 1.82 eV (20°K) in GaP crystals doped with varying amounts of the shallow acceptor Zn and the deep donor O were studied. The red-band decay is nonexponential in time, shortens with increasing zinc concentration (the concentrated dopant), is nearly independent of the oxygen concentration (the dilute dopant), is essentially constant in shape and magnitude at low temperatures, shifts to lower frequencies during decay, and is not dependent on photoconductivity during decay. These observations are in accord with the model of pair-band decay and so support the interpretation of Gershenzon et al. that the red band at 1.82 eV (20°K) is a Zn-O pair band.