Effect of thermal annealing on structure and photoluminescence properties of silicon-rich silicon oxides

The structure and optical properties of thermally annealed silicon-rich silicon oxide (SRSO) films are investigated by means of transmission electron microscopy (TEM), photoluminescence (PL), infrared (IR) and Raman spectroscopy. The samples were prepared by the reactive evaporation of SiO powder with subsequent deposition of SiOx (x≈1) thin films on quartz or sapphire substrates, followed by thermal annealing at temperatures from 350 to 1200 °C. Si nanocrystals formation in SRSO films was detected by TEM, Raman and PL spectroscopy at annealing temperatures above 950 °C. The volume fraction of the silicon phase in SRSO films was obtained from IR measurements, which, together with PL and Raman spectroscopy data, allowed us to propose a model of SRSO structure transformations under thermal annealing.