Local versus global absorption in thin-film solar cells with randomly textured surfaces

Enhanced light absorption in amorphous silicon thin films deposited on randomly textured zinc-oxide surfaces is investigated by means of a rigorous diffraction theory taking into account measured surface profiles and near-field optical data. Global absorption enhancement is obtained in the calculations for particular modifications of the random texture. We furthermore spatially resolve local domains of the surface texture, which show the strongest contribution to the absorption. Criteria on how random surfaces should look like to enhance absorption in thin-film solar cells are derived. (C) 2008 American Institute of Physics.