PHOTOLUMINESCENCE CHARACTERISTICS OF SI-DOPED IN0.52AL0.48AS GROWN ONINP 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) to 4 X 10(18) cm(-3) are reported. When the sample temp erature 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 en ergy. The peak energy variation at temperatures higher than similar to 100 K follows the usual band-edge variation with temperature suggesti ng that the PL arises from band-to-band transitions, while at temperat ures lower than similar to 50 K, donor-to-band transitions are probabl y dominant. The PL linewidth of the undoped and moderately doped sampl es decreases and then increases with temperature, whereas in the highl y doped samples, a near monotonic increase in the linewidth due to the rmal broadening was observed. In all the samples, the PL intensity sho wed in increasing degrees at higher doping levels, a temperature depen dence which is characteristic of disordered and amorphous materials.