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HL: Fachverband Halbleiterphysik

HL 77: Quantum Dots and Wires: Optical Properties II (mainly Luminescence and Electronic Structure)

HL 77.7: Talk

Thursday, March 29, 2012, 11:00–11:15, EW 203

Ultrasmall silicon nanoclusters, an ab-initio study of the photoluminescence lineshapes — •Davoud Pouladsaz — Department of Biological Physics, Max Planck Institute for the Physics of Complex Systems, Dresden, Germany

In recent years the observations in the Red Rectangle nebula, which is famous for its extended red emission, show a blue luminescence centered at 375 nm. Although it was first supposed to be associated with small neutral PAHs, small silicon nanocrystals with diameters of 1 nm are thought to be very good candidates for the carrier of this phenomenon. In this work, the optical properties of tetrahedral silicon nanocrystals Si₁₇ and Si₂₉ with hydrogen- and oxygen-passivation of surface dangling bounds are determined by the energetics of frontier orbitals and their dependence on the deformation in the relaxed excited state, using DFT, TD-DFT, and post Hartree-Fock methods. The results show a quantitative agreement between the calculated photoluminescence (PL) energy and the observed spectra better than 0.2 eV. Besides, the calculated PL linewidth agrees with experimental values within a factor of 1.2.