Photoluminescence Studies of Annealed GaAs Films Grown on Si Substrates

Abstract

AbstractLow temperature (T - 5K) photoluminescence (PL) has been measured on a variety of as-grown and annealed GaAs films grown on Si substrates by the MBE technique. The PL spectra of the annealed GaAs layers showed an apparent difference between the nomigally undoped samples with free carrier concentrations below 1015 cm−3 and the layers with dopant concentrations exceeding 1017 atoms cm−3 . The annealing caused an increase of both excitonic and defect related PL intensities in low doped samples. In heavily doped layers the annealing suppressed excitonic emission and strongly enhanced defect related luminescence bands. Observed post annealed infrared shifts of the PL peaks in the excitonic region are explained assuming a tetragonally distorted GaAs lattice under tensile stress, and an increase in stress after high temperature annealing.