Strain relief and ordering of (2×n)-Bi structure on Si(100)

Abstract

(2×n)-Bi phases formed on the Si(100) surface are studied using scanning tunneling microscopy and low-energy electron diffraction. A series of well-ordered (2×n) superlattices with n ranging from 5 to 12 are observed, resulting from the ordering of the missing Bi-dimer rows in the (2×1) Bi overlayer. Long stripes of the (2×n) unit meshes separated by missing Bi rows with almost perfect periodicities of n are found to extend through the whole terraces. The periodicity of n in the striped (2×n) structures depends on the Bi coverage and the annealing temperature. The formation of successive phases of the (2×n) structures as a function of coverage and annealing temperatures reflects various strain relief processes in the direction of the compressed Bi-dimer rows by creating missing rows and line dislocations as well as rectangular vacancies. The remarkable long-range ordering of missing Bi rows in the compressed Bi overlayer suggests the presence of strong repulsive long-range elastic interaction among missing Bi-dimer rows.