Photoluminescence study of the dynamical properties of GaAs sawtooth superlattices

Abstract

The dynamic properties of a sawtooth superlattice (δ-doped nipi) were examined by photoluminescence (PL) spectroscopic techniques. The structure was grown on a semi-insulating GaAs substrate by metalorganic vapor phase epitaxy, using C and Si δ-doping. The excitation intensity dependence of the sample’s PL was measured over six decades which produced a shift of 200 meV in the peak of the PL photon energy. The dynamic properties of the sawtooth superlattice were probed using time resolved PL and carrier lifetime measurements. Time resolved PL was measured over 6 orders of magnitude in delay time. The luminescence wavelength from the sawtooth superlattice sample was found to shift to low energies over time after pulsed excitation, indicating the temporal evolution of the band edges. A new and sensitive technique for measuring radiative recombination lifetimes at low excitation intensities was developed. Therefore δ-doped sawtooth superlattices are shown to have a tunable band gap as well as an intensity tunable carrier lifetime.