Photoluminescence studies of a GaAs-Ga1-xAlxAs superlattice at 8-300 K under hydrostatic pressure (0-70 kbar)

Abstract

The pressure dependence (0-70 kbar) of the photoluminescence spectra from a GaAs-Ga1-xAlxAs multiple-quantum-well (MQW) structure is reported at 8-300 K. The pressure coefficients of the EnhΓ and EnlΓ (n=1, 2) transitions between the Γ conduction subbands and the heavy- (h) and light- (l) hole bands are determined. The energy of E1hΓ has a sublinear pressure dependence for the MQW at 80 K but not at 300 K. The reverse is true for the band gap of bulk GaAs. In the MQW the Γ and X bands cross around 35 kbar and a new transition E1hX, observed for the first time, has a pressure coefficient of -1.3±0.1 meV/kbar at 80 K. The X-Γ band separation at atmospheric pressure in the bulk is deduced to be 45-50 meV lower than the previously accepted value of 0.464 eV. The carrier lifetimes in the Γ and X bands and the Γ-to-X scattering times are deduced.