SPATIAL-DISTRIBUTION OF A-SI-H FILM-PRODUCING RADICALS IN SILANE RF GLOW-DISCHARGES

Film growth on glass fibers (40 μm diameter) is used to probe the distribution of SiH4 decomposition products that produce a-Si:H films in silane rf glow discharges. The film thickness on fibers spanning the electrodes is measured versus position to map the spatial variation of the film-precursor (radical) density. The optical emission from the discharge, which is shown to be essentially equivalent to the distributed source of SiH 4 decomposition products, is compared to the density maps. This comparison shows that the SiH3 radical dominates deposition, that this SiH3 is produced in the optically bright regions of the discharge, and that H atoms react rapidly with SiH4 before diffusing significant distances in the discharge. The perturbative nature of the probes on the discharge environment is also addressed.