FUNDAMENTAL PHENOMENA IN HETEROEPITAXIAL GROWTH STUDIED BY SCANNING-TUNNELING-MICROSCOPY

We have used scanning tunneling microscopy to study the heteroepitaxia l growth of transition metal silicides on Si by molecular beam epitaxy , in particular the temperature-induced phase transition from pseudomo rphic FeSi2 to beta-FeSi2/Si(111). Prior to the transformation the cub ic silicide films become laterally inhomogeneous which can be explaine d by a local distortion towards the orthorhombic beta-FeSi2 phase. On stoichiometrically grown samples beta-FeSi2 nucleates in a (101)-orien tation as in solid phase epitaxy. From slightly Fe-rich initial deposi ts high-quality epitaxial beta-FeSi2 with a (001)-orientation and a gr ain size of several mum could be grown. The elastic strain is relaxed by a dense array of buried misfit dislocations.