SURFACE-MORPHOLOGY OF SEMICONDUCTING IRON SILICIDES GROWN ON SI(111)

A surface roughness analysis of beta-FeSi2 films grown by solid phase epitaxy on Si(111) substrates is presented. The composition and stoichiometry of the silicides are determined by X-ray photoemission spectroscopy. Pinholes are detected in thick samples grown by the SPE method. Quantitative measurements of the roughness for different FeSi2 thicknesses are based on scanning tunneling microscopy imaging of the films. At small lateral scale (hundreds of angstroms) all the films present similar granular structures at their surface. Contrary, at larger lateral scale (of the order of a micrometer) an extra-roughness is developed for thicker FeSi2 films. Scanning electron microscopy micrographs of the same samples are consistent with these results and also give the pinhole density of the grown films. Images of an as-deposited iron film on the same substrate strongly support the idea that roughness appears during the solid phase epitaxy growing procedure.