Control of nucleation and growth in the preparation of crystals by plasma-enhanced chemical vapour deposition

Abstract

Abstract Both microcrystalline silicon (μc-Si) and epitaxial silicon (epi-Si) have been prepared by plasma-enhanced chemical vapour deposition from SiF4 with the assistance of atomie 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≤3) with atomie hydrogen in the gas phase. Either μe-Si or epi-Si was grown at a deposition rate of 10 å s−1 or more from these precursors by selecting conditions of atomie hydrogen flow rate and substrate temperature Ts. The appropriate condition for growing crystals with large grains including epi-Si is distinguished from that for making μc-Si where the formation of nuclei is dominant. An attempt was made to control the surface reactions by adding the species SiH n and atomie hydrogen for the purpose of modulating the silicon network.