Annealing simulations to determine the matrix interface structure of SiC quantum dots embedded in SiO 2

We use the Density Functional based Tight-Binding (SCC-DFTB) method in a Quantum Mechanics/Molecular Mechanics embedding scheme to simulate single SiC quantum dots of different shapes and with diameters of up to 1 nm, embedded in a block of α -Quartz with cell vectors of a = 15 nm and c = 13 nm. First results show that during the annealing process three recurring motives appear at the SiC/SiO2 interface of the embedded nanocrystals: Si-Si bonds often in Si interstitial-like configurations, C-C bonds involving all possible combinations of sp3 and sp2 hybridized carbon and threefold coordinated oxygen atoms. All of these defects, alone or in complexes, may play a crucial role in quenching the luminescence of these embedded nanocrystals. Detailed studies of the spectroscopic properties if the point defects identified in this work is indicated (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)