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Title: Effects of local field and inherent strain in reflectance anisotropy spectra of A{sup III}B{sup V} semiconductors with naturally oxidized surfaces

Reflectance anisotropy (RA) spectra of naturally oxidized (001) surfaces of GaAs and InAs crystals are measured for photon energies from 1.5 up to 5.5‚ÄČeV. The differential high-accuracy RA spectra reveal features substantially different from those caused by either a reconstruction of clean surface or a built-in near-surface electric field. Models of atomic structure with anisotropic transition layers of excess arsenic atoms specific for GaAs(001)/oxide and InAs(001)/oxide interfaces are proposed. In conformity with these models, a general theory of reflectance anisotropy is developed for semiconductor/oxide interfaces within the Green's function technique. The theory takes into account the combined effect of local field due to interface dipoles and of intrinsic near-surface strain of the crystal. Measured RA spectra are analyzed in the model of valence-bond dipoles occupying a rectangular lattice in a multilayer medium. Comparing the measured and calculated spectra, we conclude that RA spectra of oxidized GaAs(001) and InAs(001) surfaces are simultaneously influenced by interface and near-surface anisotropies. The former is responsible for the broad-band spectral features which are associated with polarizability of the valence bonds attached to As atoms at the crystal/oxide interface. The near-surface anisotropy is due to inherent uniaxial straining the near-surface region of crystal. The effect ofmore » strain on RA spectra is experimentally and theoretically substantiated for GaAs crystal wafers undergone a uniaxial applied stress. Basically, this work results in the following. It establishes the physical nature of different levels of RA spectra observed in a majority of papers, but never analyzed. It demonstrates how the studied features of RA spectra could be applied for optical characterization of strained interfaces and atomic layers.« less
Authors:
; ;  [1]
  1. Ioffe Physical Technical Institute of the Russian Academy of Sciences, 26 Politekhnicheskaya, 194021 Saint Petersburg (Russian Federation)
Publication Date:
OSTI Identifier:
22493106
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; ARSENIC; COMPARATIVE EVALUATIONS; CRYSTALS; DIPOLES; ELECTRIC FIELDS; EV RANGE; GALLIUM ARSENIDES; GREEN FUNCTION; INDIUM ARSENIDES; INTERFACES; OXIDES; PHOTONS; POLARIZABILITY; SEMICONDUCTOR MATERIALS; SPECTRA; STRAINS; STRESSES; SURFACES; THEORETICAL DATA