Theoretical study of the luminescent substoichiometric silicon oxides (SiOx)

Hajnal, Zoltán and Deák, P. and Köhler, Th. and Kaschner, R. and Frauenheim, Th. (1998) Theoretical study of the luminescent substoichiometric silicon oxides (SiOx). Solid State Communications, 108 (2). pp. 93-97. ISSN 0038-1098

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Abstract

Density-functional based tight-binding molecular-dynamics and semiempirical molecular orbital calculations are applied to identify the 1.9 eV luminescence center in SiOx. The identification is made possible by an 890 cm−1 vibrational line that is correlated to the luminescence peak. Two possible models are examined: (i) Si6 rings in substituted siloxenes are known to show 1.8 eV emission. A model SiO crystal is built based upon Si rings interconnected by bridging O atoms. The structure is found to be stable up to 1000 K, but the correlated vibration is not observed. (ii) a-SiO is exposed to simulated annealing and the quenched amorphous structure is analysed for occurance of Si rings and the previously proposed non-bridging oxygen hole centers (NBOHCs). Localized stretching vibrations of the NBOHCs are found to be in the experimentally detected frequency range, thus explaining the correlation with the observed and calculated photoluminescence peak.

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