Enhanced optical properties of in situ passivated near-surface AlxGa1-xAs/GaAs quantum wells

Abstract

An epitaxial method for in situpassivation of epitaxial Al x Ga1−x As/GaAs surfaces is reported. The deposition of an ultrathin InP layer (about one monolayer) on the surface of Al x Ga1−x As/GaAs structures by metalorganic vapor phase epitaxy results in drastically reduced surface recombination. The effect is studied by low‐temperature photoluminescence of near‐surface Al0.22Ga0.78As/GaAs quantum wells where the top barrier thickness is varied from 0 to 50 nm. At the thicknesses of ≤5 nm, the intensity from passivated samples is more than four orders of magnitude larger than that obtained from unpassivated structures. For a passivated surfacequantum well where InP is deposited directly onto the GaAsquantum well, we observe a blueshift of 15 meV and an intensity reduction of only a factor of 10 as compared to the luminescence from a quantum well placed at a depth of 50 nm from the surface.