Formation and chemical selectivity of partially Ga-terminated Si(111) surfaces

Nanoscale stripes of the Si(111)-(7 x 7) structure with atomic accuracy can be formed on the (root 3x root 3)-Ga-terminated Si(lll) surface, by selective thermal desorption of Ga atoms from step edges, when the surface is tilted toward the [(1) over bar (1) over bar 2] direction. The nanoscale stripes of the 7 x 7 structure can also be formed in expected areas by selective thermal desorption of Ga atoms induced by STM stimulation. A Ga-terminated area is found to be chemically less active for adsorption of oxygen, disilane and antimony molecules which selectively react in the 7 x 7 area. By using the chemical selectivity and the nanoscale 7 x 7 stripe for formation method, a stripe pattern with the antimony-adsorbed 7 x 7 areas and (root 3 x root 3)-Ga areas is produced as a demonstration of nanostructure formation.