Ordering of Missing-Row-Defects Forming (2×n)-Bi Phases on the Si(100) 2×1 Surface Studied by the Scanning Tunneling Microscopy

Abstract

(2× n )-Bi phases formed on the Si(100) 2×1 surface are studied by LEED and scanning tunneling microscopy. A series of well ordered (2× n ) superlattices, with n ranging from 5 to 12, are observed. The STM images show that the (2× n ) structures result from the formation of the periodic arrays of the missing Bi-dimer rows. The n of the (2× n ) structure is found to depend on the Bi coverage θ with a relationship of θ=1-1/ n . However, for the phases with n smaller than 5, the ordering of missing rows in the “ n ” direction is found to be disturbed by the competing formation of rectangular and linear type defects. The formation of successive (2× n ) phases as a function of coverage suggests the presence of strong long range repulsive elastic interactions among missing Bi-dimer rows.