Angle-dependent photoluminescence spectra of hydrogenated amorphous silicon thin films

Multiple sharp peaks were observed in the visible photoluminescence spectra of amorphous silicon thin films, prepared by ultrahigh vacuum electron cyc lotron resonance chemical vapor deposition on oxidized silicon substrates. The angular dependence of the photoluminescence, measured by a home-built f iber-optics device, revealed that the origin of these sharp features was du e to Fabry-Perot cavity interference effects. The interference is enhanced by deposition on thermally grown oxide layers with relatively smooth surfac es. We also consider how thin-film interference effects can add to the alre ady existing confusion regarding the photoluminescence (PL) mechanism of po rous and other luminescent forms of silicon and propose angle-dependent PL spectroscopy as a remedy for identifying spectral features due to interfere nce effects. (C) 2000 American Institute of Physics. [S0003-6951(00)00247-3 ].