Light trapping characteristics of metal nanoshells deposited on photovoltaic silicon films

Light trapping characteristics of Ag nanoshells deposited on photovoltaic silicon films were studied theoretically using finite difference time domain (FDTD) method. The light absorption changes in Si films are found dependent on the localized surface plasmon resonance (LSP) including scattering, absorption and their respective portions, which can be tuned by varying the size of the metal nanoshells. Predominant scattering over absorption is demonstrated to be a prerequisite for the absorption enhancement. Metal absorption loss at LSP cavity mode resonance is responsible for the light absorption suppression. It is also found that the thickness of the active layer, which has effect on the LSP interference-induced field, influences light trapping characteristics of the Ag nanoshells.