Photoluminescence characteristics of Si-doped In 0.52Al 0.48As grown on InP substrates by molecular beam epitaxy

Abstract

The photoluminescence (PL) characteristics of Si-doped In 0.52Al 0.48As layers as a function of temperature and silicon doping level ranging from 1 × 10 17 to 4 × 10 18 cm −3 are reported. When the sample temperature is increased from 4 K, the PL peak energy exhibits an inverted S-shaped dependence which is characteristic of carrier localization. This effect was more prominent at lower doping levels but weakened at high doping levels due to a possible reduction in the donor binding energy. The peak energy variation at temperatures higher than ∼ 100 K follows the usual band-edge variation with temperature suggesting that the PL arises from band-to-band transitions, while at temperatures lower than ∼ 50 K, donor-to-band transitions are probably dominant. The PL linewidth of the undoped and moderately doped samples decreases and then increases with temperature, whereas in the highly doped samples, a near montonic increase in the linewidth due to thermal broadening was observed. In all the samples, the PL intensity showed in increasing degrees at higher doping levels, a temperature dependence which is characteristic of disordered and amorphous materials.