AVS 50th International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThM

Paper SS1-ThM4
Current-Induced Pattern Formation on Vicinal Surfaces

Thursday, November 6, 2003, 9:20 am, Room 310

Session: Patterned Growth and Etching of Semiconductors
Presenter: T. Zhao, University of Maryland
Authors: T. Zhao, University of Maryland
J.D. Weeks, University of Maryland
Correspondent: Click to Email
Vicinal surfaces can exhibit a number of different morphological instabilities that may be important in crystal growth and nano-scale device fabrication. Particularly interesting step bunching and step wandering patterns arise from electromigration on Si(111) surfaces; these patterns are observed depend on both the current direction and the temperature. We develop a new two-region diffusion model where adatoms in a small region near a step are assumed have different diffusion rates from those on terraces due to different surface reconstruction or bonding configurations near the step. A linear stability analysis of this theoretical model yields both the bunching behavior and the most unstable wavelength for in-phase wandering. We find good agreement with existing experiments.@footnote 1@ Moreover, to account for the long time behavior of such surfaces, we use a geometric representation of the interface to derive a nonlinear evolution equation for a step in the presence of anisotropic diffusion arising from the electric field. The evolution of the step resulting from fields oriented with different angles off the z-axis bears strong resemblance to the experiments.@footnote 2@ @FootnoteText@ @footnote 1@ See M. Degawa, K. Thürmer, I. Morishima, H. Minoda, K. Yagi, and E.D. Williams, "Initial stage of in-phase step wandering on Si(111) vicinal surfaces," Surf. Sci. 487, 171 (2001)@footnote 2@ See M. Degawa, H. Minoda, Y. Tanishiro, and K. Yagi, "In-phase step wandering on Si(111) vicinal surfaces: Effect of direct current heating tilted from the step-down direction," Phys. Rev. B 63, 045309/1 (2001).