Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.3: Poster

Montag, 26. März 2007, 15:00–17:30, Poster A

Interface influence on optical properties of Si-SiO₂ structures — •Kaori Seino, Jan-Martin Wagner, and Friedhelm Bechstedt — Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena, Germany

Prototypical Si-based systems to study quantum-size effects are short-period Si-SiO₂ multiple quantum wells (MQWs). The application of Si-SiO₂ layered system in multi-junction solar cells for future photovoltaics requires an optimum band structure design. Their fabrication as nm-scale superlattice allows a band-gap tuning. The understanding of optical properties in Si-SiO₂ multilayer structures is essential for their application.

Here we present results for optical properties of Si-SiO₂ MQWs obtained by means of first-principles calculations. The calculations for optical properties have been widely performed within the independent-particle approximation. We investigate the dependence on the thickness of the silicon layer, varying in the range from 1 to 4 nm, for several structural interface elements ensuring dangling-bond passivation at the interface. Our results demonstrate vertical confinement effects on the optical properties for both the fundamental gap and the oscillator strength of Si-SiO₂ superlattices with nm-sized layers.