Effect of InP passivation on carrier recombination in In/sub x/Ga/sub 1-x/As/GaAs surface quantum wells

Carrier recombination in surface and near-surface In/sub x/Ga/sub 1-x/As/GaAs quantum wells was studied using time-resolved and cw photoluminescence spectroscopy. Surface passivation by an ultrathin layer (1 ML) of InP was found to yield dramatically enhanced luminescence intensity. A blue shift due to the vacuum barrier on the surface was measured to be as high as 70 meV for a passivated 3 nm thick In/sub 0.25/Ga/sub 0.75/As/GaAs surface QW. The carrier recombination dynamics was studied for 7 nm thick In/sub 0.10/Ga/sub 0.90/As/GaAs surface and near-surface QWs. A carrier lifetime of 40 ps was obtained for an unpassivated near-surface QW whereas lifetimes of 300 ps and 245 ps were measured for passivated near-surface and surface QWs, respectively. The results indicate that the passivation reduces the surface recombination remarkably.