AVS 49th International Symposium
    Nanometer Structures Wednesday Sessions
       Session NS-WeM

Paper NS-WeM4
Dynamics of Br-Si(100)-(2x1): Surface Modification in the Absence of Desorption

Wednesday, November 6, 2002, 9:20 am, Room C-207

Session: Nanostructured Materials
Presenter: E. Graugnard, University of Illinois at Urbana-Champaign
Authors: E. Graugnard, University of Illinois at Urbana-Champaign
G. Xu, University of Illinois at Urbana-Champaign
V. Petrova, University of Illinois at Urbana-Champaign
K.S. Nakayama, University of Illinois at Urbana-Champaign
J.H. Weaver, University of Illinois at Urbana-Champaign
Correspondent: Click to Email
The dynamics of surface modification of Si(100)-(2x1) with Br has been studied using variable temperature scanning tunneling microscopy (STM). A clean surface was saturated with Br at room temperature and then heated on the STM stage to 700 K, where no surface modification was expected. To our surprise, we found that the surface was, in fact, modified after heating for several hours. From sequential images of the same area, we were able to observe the formation and growth of novel defect structures, which consist of parallel atom vacancy lines separated by a single dimer row and could grow to be 120 nm in length. The formation of these vacancy lines was accompanied by Si adatom transfer onto the terrace, where regrowth dimers could form. The vacancy lines were often terminated at regrowth chains or dimer vacancy pits. We observed diffusion of regrowth features, but diffusion was limited to regions of the terrace where there were no vacancy structures. Thus, regrowth islands formed on defect-free areas of the terrace, and these islands limited the growth of the defect lines. As the surface roughened, the dynamics of the features became increasingly complicated with the atom vacancy lines converting into dimer vacancy lines and vice versa. The formation mechanisms and dynamics of these surface structures will be discussed.