STM and Raman study of the evolution of the surface morphology in mu c-Si:H

The structure of mu c-Si:H films deposited on graphite substrates has been investigated, using scanning tunneling microscopy and Raman scattering spectroscopy as a function of film thickness ranging from 1 to 10 nm. At the very initial stage of deposition, chemically active sites are created on the surface of the graphite substrate, which is evidenced by a change in the graphite Raman bands. A change of the STM image found in the early stage of growth is interpreted in terms of a coalescence of nanostructures. The vertical surface roughness of mu c-Si:H is found to be much larger than that of a-Si:H, which can be explained by its inhomogeneous nature as well as crystallographic anisotropy of the mu c-Si:H film.