Characterization of Off Stoichiometric Silicon Oxide by Thermo, Cathode, and PhotoLuminescence

Off Stoichiometric Silicon Oxide, or Silicon Rich Oxide (SRO), obtained by LPCVD was studied by Photo, Cathode and Thermo luminescence. The Silicon excess in the SRO films varied between 2 and 12 % at. In the deposited samples, the luminescence was observed in the blue region by all techniques. This is an indication that the high temperature used during the deposit produces point defects. After annealing at 1100 °C in nitrogen during 3 hours, the blue emission is still observed suggesting that the nanopoints responsible of the blue emission are not affected. However, after annealing, the photoluminescence of SRO 30, with 5 % of silicon excess, shows drastic increase of the red emission contrarily to the cathodoluminescence, which, after annealing the blue emission, has a big increment. This contradictory observation cannot be explained as a simple emission of oxide defects, rather a mixed model that includes the effect of charge trapping characteristic of the SRO and coulombic interaction, is proposed. Still, more work has to be done to have a detailed mixed model that predicts the emission of the SRO films obtained by LPCVD.