Surface structures of β- FeSi2 formed by heat-treatment in ultra-high vacuum and their influence on homoepitaxial growth

Abstract We have studied the surface structures of single crystalline β - FeSi 2 substrate and their influence on homoepitaxial growth. After heat-treatment in ultra-high vacuum above 750 °C, where the native oxide layer (SiO x ) on the substrate was removed, characteristic structures depending on the surface orientation were formed on the substrate. On the β - FeSi 2 (100) substrate, the round shaped dip structures with conical elevation appeared after heat treatment above 800 °C. The composition of the dip structures was partially Fe-rich as compared with nominal β - FeSi 2 composition (Si/Fe=2). These characteristic structures significantly affected the crystalline quality. They remained in the epitaxial layer after thin film growth. We also achieved homoepitaxial β - FeSi 2 films on β - FeSi 2 (111) substrate at the growth temperature of 700 °C and 800 °C.