Berlin 2008 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Poster: Trends in Ion Beam Technology, Magnetism in Thin Films, Functional Oxides, High-k Dielectric Materials, Semiconductor Nanophotonics, Nanoengineered Thin Films, Layer Deposition Processes, Layer Growth, Layer Properties, Thin Film Characterisation, Metal and Amorphous Layers, Application of Thin Films

DS 17.19: Poster

Tuesday, February 26, 2008, 09:30–13:30, Poster A

Si nanocrystals in amorphous silica: atomistic models of the interface — •Flyura Djurabekova and Kai Nordlund — University of Helsinki

The poor optical properties of silicon due to its indirect bandgap have until now limited its application in optoelectronics. A novel nano-crystalline approach has disclosed a new prospect for silicon in this field. The observed superior light emitting properties (compared also to porous silicon) of silicon nanocrystals (Si-nc) embedded into amorphous silica ( a-SiO₂) are associated with more stable Si/a-SiO₂ interfaces in the new structures. However, the mechanism of this phenomenon still remains unclear. The active role of Si-nanocrystal interface for the optical properties has been discussed intensively. In the present work, we report the creation of atomistic models of the interface by means of molecular dynamics atomistic simulations. Small Si-nc embedded into defect-free a-SiO₂ are constructed using two different classical interatomic potentials. After series of annealing runs, the interface structure and defects are carefully analyzed. The results show a thin suboxide layer along with mostly undercoordinated defects at the interface region.