Time-resolved photoluminescence study of GaInAs/AlGaInAs superlattices

Abstract We present results of time-resolved photoluminescence experiments performed at 77 K on a GaInAs/AlGaInAs superlattice grown by molecular beam epitaxy and lattice matched to an InP substrate. The superlattice is the intrinsic part of a p–i–n diode. Photoluminescence spectra, reconstructed at various delay times between 5 ps and 100 ps after the laser pulse, show lines associated to the 1s and 2s heavy-hole exciton states and to the free carrier recombination. This result provides a direct determination of the binding energy of the heavy-hole exciton which is shown to be equal to 15 meV. Such a large value of the Rydberg is due to the fluctuations of composition which cause the heavy-hole exciton to be localized within a single well. The spectra also exhibit a shoulder which corresponds to the electron-to-light-hole transition. The 2s heavy-hole-exciton transition is coupled to the latter by an LO phonon. Finally a transition 21 meV below the 1s heavy-hole-exciton energy is related to Be residual impurities.