Photoluminescence of heavily doped GaAs and Ga0.85In0.15As

Abstract

Zinc-doped, p-type, GaAs and Ga0.85In0.15As samples with a carrier concentration up to p = 1.95 × 1020 cm−3 were studied by low-temperature photoluminescence. At low doping levels, recombinations involving impurity states provide a measurement of the zinc-acceptor binding energy in the Ga0.85In0.15As alloy. At high concentrations, the discrete acceptor levels are replaced by an impurity band. In the presence of a high density of impurities, potential fluctuations and interparticle interactions result in a band-gap renormalization that is observed with photoluminescence experiments. This phenomenon is analyzed on the basis of available models that take into account the nonconservation of momentum for optical transitions as well as many-body effects.