Near-surface QWs in GaAs: Recovery of Emission Efficiency Via Surface Passivation by Hydrogen and Stability Effects

The role of surface states in reducing the radiative efficiency of a GaAs/AlGaAs quantum well (QW), situated in proximity of the surface, has been investigated. The near-surface QW photoluminescence (PL) was utilized as a probe of the effects of room-temperature hydrogen irradiation and of the subsequent evolution of the system in time. The e1 - hh1 PL at 1.4 K of various near-surface wells, differing in distance from the surface, was found to drop when the AlGaAs barrier was made thinner than 150 angstroms, due to short-circuiting recombination processes at the surface. The data were interpreted in terms of electron and hole tunneling to surface states. A study of the stability of the passivation effect -- samples being investigated again after an eight-month-long exposure to air, or after annealing in vacuum -- is indicative of important changes in the lifetimes of the different radiative and non-radiative processes associated with the well.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.