Free-standing silica film containing Si nanocrystals: Photoluminescence, Raman scattering, optical waveguiding, and laser-induced thermal effects

摘要

A Raman and photoluminescence study of a thermally annealed free-standing film of silica containing Si nanocrystals is reported. The laser-induced thermal effects are observed, including the increase of the absorption coefficient and the strongly nonlinear rise of the light emission. The light emission measured at high excitation powers is probably blackbody radiation, and the Raman measurements confirm high laser-induced temperatures. The Ar~+ laser annealing strongly increases the crystalline Raman peak showing that thermal annealing at 1150 ℃ does not finish structural reorganization of the SiO_x material. In the waveguiding detection geometry, the spectral narrowing of the photoluminescence is observed.