Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 84: Poster: Electronic structure theory / Carbon (other than graphene) / Si, Ge, and SiC / III-V semiconductors (other than nitrides)

HL 84.9: Poster

Mittwoch, 2. April 2014, 17:00–20:00, P1

Electronic and optical properties of amorphous Ge nanocrystals in a crystalline Si matrix — •Moritz Laubscher¹, Sebastian Küfner¹, Jürgen Furthmüller¹, Peter Kroll², and Friedhelm Bechstedt¹ — ¹Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena, Germany — ²Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019, USA

Embedded Ge nanocrystals have been discussed as promising elements for novel optoelectronic devices, because of their luminescence and charge rentention properties. The low dimensionality, together with the heterojunctions formed by the nanocrystals and the matrices, lead to (unique) quantum-confined electronic states and therefore new tunable electronic and optical properties. In contrast to the well investigated embedded c-NC, amorphous Ge nanocrystalls have not been studied in an ab-initio framework. Usually, Ge NCs show quantum confinment effects, e.g. size-depended photoluminescence. The Ge/Si interfaces most likely build a type II heterostructure. It is not known how amorphousness together with quantum confinment and the interface between NCs and matrices effect electronic structure and therefore optical properties. In this study we use a algorithm analogue to the WWW-algorithm in order to generate embedded amorphous nanocrystals and the density functional theory with the Tran-Blaha approximation to simulate the electronic and optical properties near the fundamental gap with quasiparticle corrections. We discuss optical properties and possible photoluminescence by calculating optical dipole matrix elements.