Optial Investigation of High-mobility Dilute Two-Dimensional Hold Gases in GaAs (311) A Quantum Structures

We have investigated the photoluminescence (PL) and inelastic light-scattering spectra of dilute two-dimensional (2D) hole gases of ultra-high mobility. The samples were GaAS-Al sub x Ga sub (1-x) As (311) A quantum structures, modulation-doped with Si. We find these samples not be deplete fully on illumination. The PL displays both excitonic and 2D hole gas transitions. We observe inelastic ligh-scattering, resonating on these intersubband transitions. Our measured intersubband excitation energies are in agreement with current calculations. These resonance enhancements are consistent with an electron-like dispersion of t he first-excited hole subband at zero magnetic field.