Effect of uniform compression on photoluminescence spectra of GaAs layers heavily doped with beryllium

Abstract

The effect of high-temperature annealing at high hydrostatic pressures on photoluminescence of heavily doped GaAs:Be layers grown by molecular-beam epitaxy on GaAs substrates was studied. A blue shift of the band-edge luminescence line and an increase in the relative intensity of the shoulder at the high-energy wing of this line were detected after annealing in the spectra of layers with a beryllium atom concentration higher than 5×1019 cm−3. The same layers featured a concentration-related decrease in the GaAs lattice parameter, which does not conform to the Vegard law. These effects can be attributed to the formation of beryllium inclusions in heavily doped GaAs. Due to different compressibility and thermal expansion coefficients of Be inclusions and GaAs, high-temperature and high-pressure treatment gives rise to structural defects; hence, the probability of transitions that are indirect in the k space increases.