Effects of 7-MeV electron irradiation on photoluminescence from 1-eV GaInNAs-on-GaAs epilayers

We have investigated the influence of 7-MeV electron irradiation (1.2×1015 and 1.8×1016 electrons/cm−2 doses) and subsequent rapid thermal annealing (RTA) on luminescence efficiency of nearly lattice-matched 1-eV GaInNAs-on-GaAs thin epilayers, grown by molecular beam epitaxy. The study has been done by means of 9 K photoluminescence (PL) in conjunction with 300 K photoreflectance (PR) spectroscopy and x-ray diffraction (XRD) measurements. An enhancement in PL has been found for the lower dose whereas a drastic deterioration in PL has been seen for the higher dose. When rapid thermally annealed at 800 °C for 1 min an enhancement in PL has been observed, noticeably for the sample irradiated at a higher dose, as compared to the reference non-irradiated sample. The irradiation-promoted enhancement in PL upon annealing has been accompanied by a small additional blue shift (BS) of the PL. This additional annealing-induced BS has been found, by PR and XRD, to be due to an irradiation-promoted enhancement in In–N bonds formation, whose magnitude appears to not depend on dose within the studied range.