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 re gime of carriers tunneling from the quantum well to surface states, th e PR signal from the well decreases, until vanishing when tunneling do minates 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 an d the well itself. Copyright (C) 1996 Elsevier Science Ltd