Nucleation and coalescence in hydrogenated amorphous silicon studied by scanning tunneling microscopy

Abstract
Direct subnanometer‐scale observation was made on an ultrathin film of hydrogenated amorphous silicon deposited on a highly oriented pyrolytic graphite substrate, using a ultrahigh vacuum scanning tunneling microscopy. Subnanostructures with a size of 5–10 Å were observed on the top surface independent of the film thickness below 400 Å, which are speculated to be SiH3. It is demonstrated that coalescence between nuclei (clusters) is enhanced by a surface diffusion of SiH3 precursors.