GaAsSb bandgap, surface fermi level, and surface state density studied by photoreflectance modulation spectroscopy

J. S. Hwang, J. T. Tsai, I. C. Su, H. C. Lin, Yan-Ten Lu, P. C. Chiu, J. I. Chyi

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7 Citations (Scopus)

Abstract

The bandgap, surface Fermi level, and surface state density of a series of GaAs 1-xSb x surface intrinsic-n + structures with GaAs as substrate are determined for various Sb mole fractions x by the photoreflectance modulation spectroscopy. The dependence of the bandgap on the mole composition x is in good agreement with previous measurements as well as predictions calculated using the dielectric model of Van Vechten and Bergstresser in Phys. Rev. B 1, 3551 (1970). For a particular composition x, the surface Fermi level is always strongly pinned within the bandgap of GaAs 1-xSb x and we find its variation with composition x is well described by a function E F 0.70 - 0.192 x for 0 x 0.35, a result which is notably different from that reported by Chouaib [Appl. Phys. Lett. 93, 041913 (2008)]. Our results suggest that the surface Fermi level is pinned at the midgap of GaAs and near the valence band of the GaSb.

Original languageEnglish
Article number222104
JournalApplied Physics Letters
Volume100
Issue number22
DOIs
Publication statusPublished - 2012 May 28

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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