Abstract
Light absorption by nanostructured surfaces of silicon, relevant to the capture of solar radiation, has been modeled starting from their atomic structure and calculating electronically excited states. Thin, twoโlayer silicon slabs were cut from a model optimized amorphous supercell and studied to elucidate the effect of adsorbate geometry and size for small silver clusters chemisorbed onto the hydrogenโpassivated semiconductor surface. Density functional (DFT) and timeโdependent DFT (TDโDFT) methods were performed to calculate optical properties of the amorphous Ag~n~/aโSi surface. Optimized geometries, density of states, band gap and binding energies, and excitedโstated spectra and oscillator strengths have been calculated within the DFT and TDโDFT approaches. The results demonstrate the correlation between these properties and the size of the systems, and are compared with those we previously obtained for the corresponding crystalline Ag~n~/Si(111) surfaces. Similar trends are observed for the amorphous and crystalline silicon slabs as the number of silver atoms included in the clusters were increased. Our results demonstrate that Ag~n~ clusters adsorbed on amorphous slabs are significant contributors to increased light absorption of lower energy photons. ยฉ 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010