CONTROL OF NUCLEATION AND GROWTH IN THE PREPARATION OF CRYSTALS BY PLASMA-ENHANCED CHEMICAL VAPOR-DEPOSITION

Both microcrystalline silicon (mu-c-Si) and epitaxial silicon (epi-Si) have been prepared by plasma-enhanced chemical vapour deposition from SiF4 with the assistance of atomic hydrogen. Precursors of the form SiF(n)H(m) (n + m = 3) were made as a result of successive reduction of fluorinated fragments SiF(n) (n less-than-or-equal-to 3) with atomic hydrogen in the gas phase. Either mu-c-Si or epi-Si was grown at a deposition rate of 10 angstrom s-1 or more from these precursors by selecting condtions of atomic hydrogen flow rate and substrate temperature T(s). The appropriate condition for growing crystals with large grains including epi-Si is distinguished from that for making mu-c-Si where the formation of nuclei is dominant. An attempt was made to control the surface reactions by adding the species SiH(n) and atomic hydrogen for the purpose of modulating the silicon network.