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Split-off dimer defects on the Si(001)2x1 surface.
PHYS REV B
, Article 085312. 10.1103/PhysRevB.69.085312.
Dimer vacancy (DV) defect complexes in the Si(001)2x1 surface are investigated using high-resolution scanning-tunneling microscopy and first-principles calculations. We find that under low-bias filled-state tunneling conditions, isolated "split-off" dimers in these defect complexes are imaged as pairs of protrusions, while the surrounding Si surface dimers appear as the usual "bean-shaped" protrusions. We attribute this to the formation of pi-bonds between the two atoms of the split-off dimer and second-layer atoms, and present charge density plots to support this assignment. We observe a local brightness enhancement due to strain for different DV complexes and provide the first experimental confirmation of an earlier prediction that the 1+2-DV induces less surface strain than other DV complexes. Finally, we present a previously unreported triangular shaped split-off dimer defect complex that exists at S-B-type step edges, and propose a structure for this defect involving a bound Si monomer.
|Title:||Split-off dimer defects on the Si(001)2x1 surface|
|Keywords:||SCANNING-TUNNELING-MICROSCOPY, ELECTRONIC-STRUCTURE, SI(100) SURFACE, LOW-TEMPERATURE, DENSITY, VACANCIES, SILICON, STEPS, ROOM|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
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