Spectroscopic and Microscopic Correlation of SRO-HFCVD Films on Quartz and Silicon

This work is focused on making a correlation between results obtained by using spectroscopy and microscopy techniques from single and twofold-layer Silicon-Rich Oxide (SRO) films. SRO films single-layer and twofold-layer characterizations were compared considering the conditions as-grown and with thermal treatment at 1100 degrees C for 60 min in a nitrogen atmosphere. The thickness of the single-layer film is 324.7 nm while for the twofold-layer film it is 613.2 nm; after heat-treated, both thicknesses decreased until 28.8 nm. X-ray Photoelectron Spectroscopy shows changes in the excess-silicon in single-layer SRO films, with 10% in as-grown films and decreases to 5% for the heat-treated films. Fourier Transform Infrared Spectroscopy (FTIR) exhibits three characteristic vibrational modes of SiO2, as well as, the vibrating modes associated with the Si-H bonds, which disappear after the heat treatment. With UV-Vis spectroscopy results we obtained the absorbance and the absorption coefficient for the SRO films in order to calculate the optical bandgap energy (Eg(opt)), which increased with heat-treatment. The energy peaks of the photoluminescence spectra were used to calculate the silicon nanocrystal size, obtaining thus an average size of 1.89 +/- 0.32 nm for the as-grown layer, decreasing the size to 1.64 +/- 0.01 nm with the thermal treatment. On the other hand, scanning electron microscopy and high-resolution transmission electron microscopy images confirm the thickness of the twofold-layer SRO films as 628 nm for the as-grown layer and 540 nm for the layer with heat-treatment, and the silicon nanocrystal size of 2.3 +/- 0.6 nm for the films with thermal treatment.