Impact of stoichiometry and strain on Ge<sub>1−x </sub>Sn<sub> x </sub> alloys from first principles calculations
نویسندگان
چکیده
We calculate the electronic structure of germanium-tin (Ge$_{1-x}$Sn$_{x}$) binary alloys for $0 \leq x 1$ using density functional theory (DFT). Relaxed with semiconducting or semimetallic behaviour as a function Sn composition $x$ are identified, and impact epitaxial strain is included by constraining supercell lattice constants perpendicular to [001] growth direction Ge, zinc telluride (ZnTe), cadmium (CdTe) substrates. It found that application 1% tensile reduces required bring (positive) direct band gap zero approximately 5% compared relaxed Ge$_{1-x}$Sn$_{x}$ alloy having same at $\Gamma$. On other hand, compressive has comparatively less on Using DFT calculated elastic constants, critical thickness thin films substrate constant estimated, validated against calculations. The analysis correctly predicts range which it becomes energetically favourable Ge$_{1-x}$Sn$_{x}$/Ge become amorphous. influence stoichiometry examined in relation reducing magnitude inverted (``negative'') $\Gamma_{7}^{-}$-$\Gamma_{8}^{+}$ gap, characteristic structure. Based our findings, strategies engineering semimetal-to-semiconductor transition via quantum confinement nanostructures proposed.
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ژورنال
عنوان ژورنال: Journal of Physics D
سال: 2021
ISSN: ['1361-6463', '0022-3727']
DOI: https://doi.org/10.1088/1361-6463/abed6f