Near-surface electronic structure on InAs(100) modified with self-assembled monolayers of alkanethiols

Surface chemical modification is used to eliminate the problem of high surface recombination velocity and control surface band bending on InAs(100). Alkanethiols, RSH; R=CH3(CH2)(n), both neat and in ethanolic solutions, are used to passivate this surface against oxidation, as characterized by Raman scattering and x-ray photoelectron spectroscopy of the adsorbate-covered and bare surfaces. The magnitude of the interfacial band bending is obtained by analysis of Raman scattering from the unscreened longitudinal optical phonon, which arises from the near-surface charge accumulation region. Removing the native oxide with a Br-2:CH3OH chemomechanical etch reduces the surface band bending, but atmospheric oxidation increases band bending to its original level over several hours. In contrast, alkanethiol passivation of InAs(100) prevents band bending for periods of up to several weeks. (C) 1999 American Institute of Physics. [S0003-6951(99)03644-X].