Above-bandgap optical properties of biaxially strained GeSn alloys grown by molecular beam epitaxy

The complex dielectric function of biaxially strained Ge1−xSnx (0 ≤ x ≤ 0.17) alloys grown on Ge (100) has been determined by spectroscopic ellipsometry from 1.2 to 4.7 eV. The effect of substitutional Sn incorporation and the epitaxial strain on the energy transitions E1, E1 + Δ1, E0′, and E2 of Ge...

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Bibliographic Details
Published in:Applied physics letters 2014-01, Vol.104 (2)
Main Authors: Richard D’Costa, Vijay, Wang, Wei, Zhou, Qian, Soon Tok, Eng, Yeo, Yee-Chia
Format: Article
Language:English
Subjects:
ALLOYS
Applied physics
Deformation mechanisms
Dependence
DIELECTRIC MATERIALS
ELLIPSOMETRY
Epitaxial growth
GERMANIUM
MATERIALS SCIENCE
MOLECULAR BEAM EPITAXY
OPTICAL PROPERTIES
Potential theory
Shear deformation
Spectroellipsometry
STRAINS
TIN
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Summary:The complex dielectric function of biaxially strained Ge1−xSnx (0 ≤ x ≤ 0.17) alloys grown on Ge (100) has been determined by spectroscopic ellipsometry from 1.2 to 4.7 eV. The effect of substitutional Sn incorporation and the epitaxial strain on the energy transitions E1, E1 + Δ1, E0′, and E2 of GeSn alloys is investigated. Our results indicate that the strained GeSn alloys show Ge-like electronic bandstructure with all the transitions shifted downward due to the alloying of Sn. The strain dependence of E1 and E1 + Δ1 transitions is explained using the deformation potential theory, and values of −5.4 ± 0.4 eV and 3.8 ± 0.5 eV are obtained for the hydrostatic and shear deformation potentials, respectively.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4862659