PRESSURE-DEPENDENCE OF PHOTOLUMINESCENCE IN INXGA1-XAS/GAAS STRAINED QUANTUM-WELLS

Photoluminescence properties of InxGa1-xAs/GaAs strained quantum wells with well widths from 13 to 120 are investigated as a function of hydrostatic pressure (0-45 kbar) at liquid-nitrogen temperature. Pressure coefficients of the E1h transitions between the quantized ground levels of the conduction band and the heavy-hole valence band are presented. A weak recombination with a pressure coefficient of -2.6 meV/kbar is identified, which is attributable to the transition related to the crossover of the band in the well layer and the X band in the barrier layer. Correlating this transition to barrier-to-well indirect recombination, the valence-band-offset fraction is given as Qv=Ev/(Ev+Ec)=0.32 for a sample with indium fraction of x=0.25. The light-hole band is, therefore, inferred to be type II. Furthermore, the pressure coefficient is found to increase with decreasing well widths, which is opposite to that observed in the GaAs/(Al,Ga)As quantum-well system. A calculation based on the envelope-function model is made to interpret this dependence. © 1990 The American Physical Society.