Ga-induced nano-facet formation on Si(1 1 n) surfaces

Surface morphology of three kinds of Si(1 1 n) surfaces during Ga deposition has been studied by scanning tunneling microscopy to investigate nano-facet formation processes on high-index silicon surfaces. It has been observed that Si( 1 1 3) surfaces with vicinal angles of ±2° changed into nano-facet structures of (1 1 2) and (1 1 5) at 1 ML Ga deposition as well as a flat Si( 1 1 3). In contrast, no faceting occurred on Si( 1 1 4). In all cases of nano-facet formation, (1 1 2) facet formed prior to (1 1 5) facet. Thus, it is considered that (1 1 2) facet formation is a driving force of nano-facet formation process. It is also considered that large angle difference between (1 1 2) and (1 1 4) prevents the facet formation on Si(1 1 4). Difference of vicinal direction appears in distribution of facet width. The facet width distribution strongly depends on the initial morphology on the surface tilted toward [3 3 2 - ] direction, while on the surface tilted toward [3 - 3 - 2], initial morphology does not affect the final facet distribution.