Effects of hydrogen dilution and B-doping on the density of Si-C bonds and properties of a-SixC1-x: H films.

This work presents a study on the effects of hydrogen dilution and boron doping on the formation of Si-C and Si-H bonds during the deposition of hydrogenated amorphous silicon carbon alloy films by plasma-enhanced chemical vapor deposition. Low power densities of 25 mW/cm² and 50 mW/cm², high pressure of 1.5 Torr, temperatures of 150 °C and 200 °C, and methane-silane gas flow ratios of 0.70 and 0.85 were chosen in order to obtain suitable films for biomedical and biological applications. FTIR spectroscopy, UV-Vis spectroscopy, atomic force microscopy and electrical dark conductivity measurements were carried out to characterize the films. The results show that hydrogen dilution decreases CH_n groups in the films and increases the Si-C and Si-H bond densities, whereas B-doping decreases the Si-C and Si-H bond densities. Undoped films with optical band gap of 2.47 eV and conductivity around of 5×10^-10 S/cm, and B-doped films with a root mean square roughness of about 1 nm and a conductivity of the order of 10^-6 S/cm were obtained. [ABSTRACT FROM AUTHOR]