Browsing by Author "Gugsa, Derese"

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    AB Initio calculation of Optical Absorption and Optical Gap of Silicon Nanocrystallites
    (Addis Ababa University, 2007-07) Gugsa, Derese
    The electronic and optical properties of hydrogenated silicon nanocrystals have been investigated both in the ground- and in an excited-state configuration, through different ab-initio techniques. The presence of an electron-hole pair leads to a strong interplay between the structural and optical properties of the system. The aim of this work was to investigate the optical properties of hydrogenated Si nanoclusters (H-Si-nc) that has recent experimental interest for photonic applications. The optical absorption spectra of small SinHm nanoclusters are computed using a linear response theory within the time-dependent local density approximation (TDLDA). The TDLDA formalism allows the electronic screening and correlation effects, which determine exciton binding energies, to be naturally incorporated within an ab initio framework. We examined that the calculated excitation energies and optical absorption gaps to be in good agreement with experiment