Unique dynamic appearance of a Ge-Si ad-dimer on Si(001).
We carry out a comparative study of the energetics and dynamics of Si-Si, Ge-Ge, and Ge-Si ad-dimers on top of a dimer row in the Si(001) surface, using first-principles calculations. The dynamic appearance of a Ge-Si dimer is distinctively different from that of a Si-Si or Ge-Ge dimer, providing a unique way for its identification by scanning tunneling microscopy (STM). Its "rocking" motion, observed in STM, actually reflects a 180 degrees rotation of the dimer, involving a piecewise-rotation mechanism. The calculated energy barrier of 0.74 eV is in good agreement with the experimental value of 0.82 eV.
Lu
Z Y
ZY
Ames Laboratory-U.S. DOE, Iowa State University, Ames, Iowa 50011, USA.
Liu
F
F
Wang
C Z
CZ
Qin
X R
XR
Swartzentruber
B S
BS
Lagally
M G
MG
Ho
K M
KM