A characteristic feature of crystalline thin-film growth of Si on a 7 × 7 superlattice surface of Si(111)

Abstract

A Si film has been grown on a 7 × 7 superlattice surface of a Si(111) substrate at 250 and 380°C. Reflection high-energy electron diffraction patterns of the Si film at 250°C consist of a diffuse 2 × 2 structure and a weak 7 × 7 structure at 380°C. The experimental results indicate that the initial growth of crystalline nuclei is caused by the crystallization of amorphous-like islands at 250°C and by the formation of an island composed of three 5 × 5 structural units with a corner hole at their center at 380°C. The formation of crystalline nuclei is discussed.