Comment on “Atomic structure model of the reconstructed Si(557) surface with a triple step structure: Adatom-parallel dimer model”

Abstract

Recently, ͓Oh et al. Phys. Rev. B 77, 155430 ͑2008͔͒ reported on an atomic model for the so-called Si͑557͒-reconstructed surface with regular triple steps. The atomic structure model proposed was developed on the basis of high-resolution scanning tunneling microscopy ͑STM͒ images and first-principles calculations performed to match such STM images. Here we argue that the STM image presented is affected by an artifact, most likely related to a multiple tip image effect. Among other issues with the image presented, the corner holes for ͑7 ϫ 7͒ reconstruction on Si͑111͒ terraces are not visible, since a doubled image superimposed smears out such characteristic depression. The ͑ϫ7͒ periodicity deduced for the edge facets, in contrast with previously reported STM images and electron-diffraction studies which unambiguously indicate a ͑ϫ2͒ periodicity, arises from the same artifact. Finally, we remark that the ͑557͒ surface orientation and ͑112͒ orientation of triple steps assumed for first-principles calculations disregard the latest experimental data available, which suggests this surface has a ͑7 7 10͒ orientation and the steps in triple step do not form a well-defined plane ͓Surf. Sci. 600, 4878 ͑2006͔͒.

Magnification Effects in Scanning Tunneling Microscopy: the Role of Surface Radicals

“…While an early STM study on this subject indicated a (557) orientation [9.5 • off the (111) plane], 13 latter works including high resolution diffraction data report a (7 7 10) orientation [10.0 • off the (111) plane]. [14][15][16][17][18][19] In conclusion, we demonstrated that the positions of bright spots in high resolution STM images and the actual coordinates of atomic nuclei may differ substantially. Elusive images can be formed on surfaces having dangling-bond states whose main axis differs from the surface normal, and that may lead to misinterpretation of the experimental data.…”

Buckling of reconstruction elements of the edges of triple steps on vicinal Si(111) surfaces

“…This is apparently due to the effective closure of dangling Si bonds at the edge of a triple step, which reduces the step formation energy. Although triple steps constitute an important part of the landscape of vicinal Si(111) surfaces, their atomic structure is still incompletely known [8]. Even the ori entation of the surface with regular triple steps is under discussion.…”

Atomically resolved scanning force studies of vicinal Si(111)

“…One-dimensional systems have been extensively studied over the last decades due to their intriguing physical properties and potential applications in nanometer-scale devices [1][2][3][4][5][6][7]. A bottom-up approach based on self-assembly on nanotemplates represents an attractive method for fabricating one-dimensional structures.…”