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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.19: Poster

Dienstag, 15. März 2011, 18:00–21:00, P3

Structural and electronic properties of silicon polymorphs — •Tobias Sander, Claudia Rödl, Kaori Seino, and Friedhelm Bechstedt — Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany

Currently, silicon has been assigned to 12 different high pressure phases from which two are still undetermined in their atomic geometries. Due to the occurrence of complex structures and metastable phases, a complete investigation of structural or even electronic properties has not been completed yet. The possible chance to find crystalline Si structures that may be applicable in photovoltaic devices has enforced the interest in a detailed investigation. Since it is little known about the atomic distributions, we performed ground-state calculations for three distinct exchange and correlation functionals (LDA, PBE, AM05) to obtain parameters like lattice constants, bulk moduli, or cohesive energies. Reflecting structural properties for semiconducting structures best, the AM05 functional has been used to investigate electronic properties such as band gaps, band offsets, and density of states (DOS). From that we classify four polymorphs to be semiconducting, including Si-XIII which has not been observed experimentally yet. We also investigated quasiparticle band structures within the GW method and compare band gap results from AM05+GW and HSE03+GW calculations. Finally, the results are completed by optical absorption spectra.