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Optical constants and critical‐point parameters of GaAs 1– x Sb x alloy films grown on GaAs
Author(s) -
Ben Sedrine N.,
Gharbi T.,
Harmand J. C.,
Chtourou R.
Publication year - 2008
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200777746
Subject(s) - overlayer , substrate (aquarium) , molecular beam epitaxy , materials science , ellipsometry , dielectric , analytical chemistry (journal) , band gap , epitaxy , oxide , thin film , optoelectronics , chemistry , condensed matter physics , nanotechnology , physics , metallurgy , oceanography , layer (electronics) , chromatography , geology
Spectroscopic Ellipsometry (SE) is used in this work to investigate the optical properties of the GaAs 1– x Sb x alloys. The present study is based on a set of GaAs 1– x Sb x layers ( x = 0.0%, 6.7% and 10.8%) grown on GaAs substrate by molecular beam epitaxy (MBE). The SE measurements were carried out in the energy range of 1.4 – 5.5 eV at room temperature for 70° and 75° incident angles, before and after chemical etching. The optical constants of GaAs 1– x Sb x alloys were extracted using the Newton–Raphson method based on the four‐phase model (ambient – GaAs native oxide overlayer – GaAs 1– x Sb x film – GaAs substrate). Analytic line shapes fitted to numerically calculated second derivatives of the dielectric functions determined the critical‐points parameters above the GaAs 1– x Sb x bandgap E 0 . The best fit parameters and the experimental extracted data show in particular a red‐shift and a broadening increase of E 1 , E 1 + Δ 1 , E ′ 0 and E 2 transitions by increasing Sb content. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)