Dimer buckling induced by single-dimer vacancies on the Si(001) surface nearTc

We used a low-temperature scanning tunneling microscope to observe a single-dimer vacancy ($A$-type defect) induce buckling of the dimers on a Si(001) surface near $T_c\approx 200\mathrm{K}.$ This dimer buckling always occurs in rows adjacent to the $A$-type defects near $T_c,$ which simultaneously forms an out-of-phase boundary in the domain of a $c(4\mathrm{}\times 2)$ structure. However, the out-of-phase boundaries around the $A$-type defects disappear on the surface at 78 K. We discuss the nucleation and growth behavior of the dimer buckling around the $A$-type defect and the influence of the defects on the structural phase transition of a Si(001) surface.