Carrier recombination in surface and near-surface InxGa1-xAs/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 a dramatically enhanced luminescence intensity. A series of passivated In0.25Ga0.75As/GaAs surface quantum wells having a well thickness of 2 to 15 nm was grown. 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 In0.25Ga0.75As/GaAs surface QW. The carrier recombination dynamics was studied for 7-nm-thick In0.10Ga0.90As/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.
- quantum wells