AVS 51st International Symposium
    Surface Science Thursday Sessions
       Session SS3-ThA

Paper SS3-ThA7
Effects of Si Deposition on Electromigration Induced Step Bunching on Si(111)

Thursday, November 18, 2004, 4:00 pm, Room 213B

Session: Surface Diffusion and Transport
Presenter: B.J. Gibbons, The Ohio State University
Authors: B.J. Gibbons, The Ohio State University
J. Noffsinger, The University of Kansas
J.P. Pelz, The Ohio State University
C. Ebner, The Ohio State University
Correspondent: Click to Email
We have studied the effects of Si deposition on direct current (DC) heating induced step bunching on Si(111) using Si samples with spherical dimples ground into the surface to create a range of surface miscut. With no Si deposition, we observe the well-known behavior that only "step-down" current produces bunching in temperature "Regime I": (<950°C), while bunching in "Regime II": (1050°C-1250°C) only occurs for "step-up" current. But in contrast to a report by Métois et al. [Surf. Sci. 440 (1999) 407] we very clearly do not observe that net growth conditions reverses the current direction required for bunching in Regime II. This is not consistent with the proposal [S. Stoyanov, Surf. Sci. 416 (1998) 200] that the primary bunching mechanism in Regime II is due to increased step permeability. However we do observe that there is a strong reduction in the density of "crossing steps" close to zero net deposition/sublimation conditions, qualitatively consistent with the simultaneous bunching/debunching model of Kandel and Weeks [Phys. Rev. Lett. 74 (1995) 3632]. We will discuss on-going work to quantify this reduction and compare it with 1D analytic and 2D Monte Carlo models. By measuring areas of the dimpled samples with different miscut, we have also found that the average step bunch height increases roughly linearly with sample miscut, but does not depend significantly on Si deposition conditions. We are also comparing this observed bunch-height dependence on miscut with 1D and 2D models to evaluate which existing model can best explain a range of step-bunching behavior. Work supported by NSF Grant DMR-0074416.