Wurtzite silicon as a potential absorber in photovoltaics: Tailoring the optical absorption by applying strain
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 4, 045207Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2015. Vol. 92, no 4, 045207
IdentifiersURN: urn:nbn:se:kth:diva-172164DOI: 10.1103/PhysRevB.92.045207ISI: 000358253200005OAI: oai:DiVA.org:kth-172164DiVA: diva2:846949
QC 201508182015-08-182015-08-142015-08-18Bibliographically approved