POWDER-FREE PLASMA CHEMICAL VAPOR-DEPOSITION OF HYDROGENATED AMORPHOUS-SILICON WITH HIGH RF POWER-DENSITY USING MODULATED RF DISCHARGE

Deposition of hydrogenated amorphous silicon films from SiH4/He gas mixtures was performed by using a square wave amplitude modulated rf discharge. The modulation was used for controlling radical densities in plasmas which led to a high rate deposition of good quality films. The fairly high deposition rate of 6 Å/s was obtained for a low concentration of 5% SiH4 and a high rf peak power 200 W (0.8 W/cm3) without any appreciable amount of powder particles in the reaction chamber. The optical gap of the films was 1.8-1.95 eV. Emission intensities of HeI 388.9 nm and SiH 413.5 nm linearly increased with rf peak power and were well correlated with the deposition rate.