Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 49: Optical Properties
HL 49.1: Talk
Thursday, March 25, 2010, 09:30–09:45, H14
Quantum confinement effect in prestine and oxygen covered silicon nanocrystals with surface states — •Sudip Chakraborty1, Subhash V Ghaisas1, Ch Rajesh2, and Shailaja Mahamuni2 — 1Department of Electronic Science, University of Pune, Pune 411007, India — 2Department of Physics, University of Pune, Pune 411007, India
Absorption spectra for prestine silicon and oxygen capped silicon nanocrystals (nc) are computed using Time Dependent Local Density Approximation (TDLDA) in the size range 1.0 to 1.5 nm. These clusters show very small Highest occupied Molecular Orbital (HOMO) - Lowest Unoccupied Molecular Orbital (LUMO) gaps. This indicates presence of surface states.The Partial Density Of States (PDOS) for these clusters confirm the presence of surface states when compared to the corresponding ncs with hydrogen passivation. The HOMO-LUMO gaps do not show any size dependence. However the optical absorption gaps show the quantum confinement effect(QCE) for both the types of clusters. The oxygen capped silicon ncs are prepared following the wet chemical route. The optical absorption spectrum of experimentally prepared ncs is compared with the computed one. Experimental results support the theoretical argument explaining the QCE in these clusters.