Surface proximity effects in III-V quantum wells investigated by photoreflectance

Photoreflectance spectroscopy (PR) of In0.1Ga0.9As/GaAs and Al0.3Ga0.7 As/GaAs near-surface quantum wells has been investigated to determine the influence of the quantum well on the surface potential. In the regime of carriers tunneling from the quantum well to surface states, the PR signal from the well decreases, until vanishing when tunneling dominates over radiative recombination in the well. This result suggests that a quantum well next to the surface has the effect of creating a nearly fiat band condition in a region comprehensive of the surface and the well itself.