SOME CHARACTERISTICS OF SILICON-DOPED IN0.52AL0.48AS LAYERS GROWN LATTICE-MATCHED ON INP SUBSTRATES BY MOLECULAR-BEAM EPITAXY

The photoluminescence (PL) characteristics of Si-doped In0.52Al0.48As layers as a function of temperature and silicon doping level ranging f rom 1 X 10(17) cm(-3) to 4 X 10(18) cm(-3) are reported. When the samp le temperature is increased from 4 K, the PL peak energy exhibits an i nverted S-shaped dependence which is characteristic of carrier localiz ation. This effect was more prominent at lower doping levels but weake ned at high doping levels due to a possible reduction in the donor bin ding energy. The peak energy variation at temperatures higher than app roximate to 100 K follows the usual band-edge variation with temperatu re suggesting that the PL arises from band-to-band transitions, while at temperatures lower than approximate to 50 K, donor-to-band transiti ons are probably dominant. In all the samples, the PL intensity showed in increasing degrees at higher doping levels, a temperature dependen ce which is characteristic of disordered and amorphous materials. (C) 1995 Academic Press Limited