Kinetics of Si monomer trapping at steps and islands on Si(001)

Abstract

Si monomers are observed in empty-state scanning tunneling microscopy images acquired between room temperature and 115t\ifmmode^\circ\else\textdegree\fi{}C. The monomers are trapped at the ends of rebonded SB-type dimer rows. When monomers thermally escape from the traps, they rapidly diffuse along the substrate dimer row until they find another unoccupied trap or return to their original trap. The binding activation barrier at isolated traps is \ensuremath{\sim}1.0 eV. A slightly lower barrier exists for monomers to hop between the ends of neighboring dimer rows---a process facilitating diffusion along segments of SB-type steps.