PHOTOLUMINESCENCE STUDY OF THE DYNAMICAL PROPERTIES OF GAAS SAWTOOTH SUPERLATTICES

The dynamic properties of a sawtooth superlattice (delta-doped nipi) w ere examined by photoluminescence (PL) spectroscopic techniques, The s tructure was grown on a semi-insulating GaAs substrate by metalorganic vapor phase epitaxy, using C and Si delta-doping. The excitation inte nsity dependence of the sample's PL was measured over six decades whic h produced a shift of 200 meV in the peak of the PL photon energy, The dynamic properties of the sawtooth superlattice were probed using tim e resolved PL and carrier lifetime measurements. Time resolved PL was measured over 6 orders of magnitude in delay time. The luminescence wa velength from the sawtooth superlattice sample was found to shift to l ow energies over time after pulsed excitation, indicating the temporal evolution of the band edges. A new and sensitive technique for measur ing radiative recombination lifetimes at low excitation intensities wa s developed. Therefore delta-doped sawtooth superlattices are shown to have a tunable band gap as well as an intensity tunable carrier lifet ime. (C) 1997 American Institute of Physics.