Microstructure and surface roughness of microcrystalline silicon prepared by very high frequency-glow discharge using hydrogen dilution

The microstructure of a series of silicon films deposited by Very high freq uency glow discharge (VHF-GD) with silane concentration in hydrogen Varying from 100% down to 1.25% has been observed with transmission electron micro scopy (TEM). The surface topography of the layers has been analysed by atom ic force microscopy (AFM). At silane concentration below 8.6%, a phase tran sition between amorphous hydrogenated silicon (a-Si:H) and microcrystalline silicon (mu c-Si:H) is observed by TEM. After this transition, the further decrease of silane concentration leads to complex changes of the crystalli ne microstructure of the layers. AFM observations of the surface reveal tha t the film rms roughness increases with the decrease of the silane concentr ation. The surface morphology is not related simply to the microstructure o f crystalline grains as observed by TEM. (C) 2000 Published by Elsevier Sci ence B.V. All rights reserved.