RESUMO
This paper is dedicated to a comparative study of pyrolysis of decamethylcyclopentasiloxane and hexamethyldisiloxane, widely used as precursors for CVD of silicon dioxide films. The pyrolysis process was carried out in a hot-wall horizontal tube reactor made from quartz within the temperature range 25-1000 degrees C. FTIR spectroscopy has been used for the analysis of gaseous reaction products in the exhaust line of the reactor. It has been found that transformation of DMPSO was initiated by the open ring in the precursor molecules with its further transformation to linear biradicals followed by the chain's growth due to radical reactions. HMDSO transformation is connected with separation of silanon, silyl and methyl radicals with following multi-type interactions of siloxane radicals and formation of non-rigorously organized three-dimensional molecules.
RESUMO
Nitrogen-doped titanium dioxide is often considered as a promising nanomaterial for photocatalytic applications. Here we report the first results of a study of APCVD of N-doped TiO2 thin films prepared with the use of ammonia as a source of nitrogen and titanium tetraisopropoxide (TTIP) as a source of Ti and O atoms. The obtained films were analyzed with X-ray diffraction, infrared spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and ellipsometry. It was found that the film growth rate in the TTIP-NH3-Ar reaction system varied insignificantly with substrate temperature in the range of 450,..., 750 degrees C and did not exceed 4.4 nm/min. Yellow and orange layers with nitrogen content of about 7.6% were formed at the deposition temperature higher than 600 degrees C. The results of the structure analysis of the deposited films showed that addition of ammonia led to stabilization of the amorphous phase in the films. The effect of ammonia on optical and photocatalytic properties was also considered.
