The transformation of cleaved Si(111)2×1 surfaces into apparent 1×1, 5×5, and 7×7 structures has been studied with the scanning tunneling microscope. Two reaction paths are identified, one proceeding through a disordered adatom arrangement into the 7×7 structure, and the other proceeding directly from 2×1 into the 5×5 structure. Near a nucleation site (step or domain boundary), the first path is favored due to the abundance of adatoms on the surface, and far from a nucleation site the second path dominates.

• Received 3 May 1990

DOI:https://doi.org/10.1103/PhysRevB.42.5391