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; Y. T. Lu; P. C. Chiu; J. I. Chyi

doi:10.1063/1.4724097

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, Y. T. Lu, P. C. Chiu, J. I. Chyi

Department of Electrical Engineering

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9 Scopus citations

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 language	English
Article number	222104
Journal	Applied Physics Letters
Volume	100
Issue number	22
DOIs	https://doi.org/10.1063/1.4724097
State	Published - 28 May 2012

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

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.",

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T1 - GaAsSb bandgap, surface fermi level, and surface state density studied by photoreflectance modulation spectroscopy

AU - Hwang, J. S.

AU - Tsai, J. T.

AU - Su, I. C.

AU - Lin, H. C.

AU - Lu, Y. T.

AU - Chiu, P. C.

AU - Chyi, J. I.

PY - 2012/5/28

Y1 - 2012/5/28

N2 - 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.

AB - 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.

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JF - Applied Physics Letters

SN - 0003-6951

IS - 22

M1 - 222104

ER -

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

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