Fractal analysis of the surface topography was used to study the effects of H dilution on the surface transport kinetics during the plasma deposition of hydrogenated amorphous Si. Images obtained from atomic force microscopy were examined using dimensional fractal analysis, and surface diffusion lengths of growth precursors were estimated from the measured correlation lengths. The addition of small amounts of H (H2/SiH4 ratios of less than 10:1) during deposition leads to a decrease in the diffusion length, but larger H dilutions resulted in an increased diffusion length. Moreover, the measured surface diffusion activation barrier was reduced from 0.20eV for deposition from pure SiH4 to 0.13eV with high H dilution. Results were consistent with recent models for precursor surface transport during low-temperature deposition, and give insight into critical processes for low-temperature Si crystallization.

Effect of Hydrogen on Adsorbed Precursor Diffusion Kinetics during Hydrogenated Amorphous Silicon Deposition. K.R.Bray, A.Gupta, G.N.Parsons: Applied Physics Letters, 2002, 80[13], 2356-8