The diffusion of Ge dimers along the substrate dimer rows of Ge(001) has been investigated with scanning tunneling microscopy. The jump frequency of on-top Ge dimers along symmetric dimer rows at room temperature is found to be eight times higher than the diffusion along asymmetric dimer rows ($0.36{\mathrm{s}}^{-1}$ versus $0.044{\mathrm{s}}^{-1}$). We ascribe this difference to limitations associated with the rocking motion that a dimer has to perform while diffusing along asymmetric dimer rows.

• Received 28 July 2005

DOI:https://doi.org/10.1103/PhysRevB.73.073311