Atomic force microscopy of ultra thin amorphous silicon films deposited on various substrate surfaces

The surface morphology and interface structure of ultra-thin amorphous silicon (a-Si:H) films deposited on glass, Si, SnO/sub 2/ and graphite substrates were investigated by in-situ X-ray photoelectron spectroscopy (XPS) and ex-situ atomic force microscopy (AFM). The growth mode varied between two dimensional homogeneous coverage and three dimensional island formation depending on the substrate material, deposition temperature and reactive plasma treatment of the substrate. The phenomena are interpreted by taking into account the surface diffusion of adsorbed precursors and the wettability of a-Si:H with the substrate surface. Chemical modification of substrate surface is shown to exhibit a remarkable effect on the growth mode of a-Si:H.