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- Roedl, C., et al.
(författare)
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Wurtzite silicon as a potential absorber in photovoltaics : Tailoring the optical absorption by applying strain
- 2015
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 92:4
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Tidskriftsartikel (refereegranskat)abstract
- We present ab initio calculations of the electronic structure and the optical properties of wurtzite Si (Si-IV). We find an indirect band gap of 0.95 eV (Gamma(5) -> M-1) and an optically forbidden direct gap of 1.63 eV (Gamma(5) -> Gamma(10)), which is due to a backfolding of the L-1 state of Si in the diamond structure (Si-I). Optical absorption spectra including excitonic and local-field effects are calculated. Further, the effects of hydrostatic pressure, uniaxial strain, and biaxial strain on the absorption properties are investigated. Biaxial tensile strains enhance the optical absorption of Si-IV in the spectral range which is relevant for photovoltaic applications. High biaxial tensile strains (>4%) even transform Si-IV into a direct semiconductor.
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