AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS-TuP

Paper SS-TuP20
Silicide Island Nucleation Behavior for Co/Si(111) Studied with STM and LEEM

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: T.H. McDaniels, Arizona State University
Authors: T.H. McDaniels, Arizona State University
P.A. Bennett, Arizona State University
Correspondent: Click to Email
We have measured the coverage and temperature dependence of island nucleation during deposition of Co on Si(111)-7x7 using STM for low temperature and LEEM for high temperature. Below 500C, 3 distinct structures occur: "lowered" regions mostly on the unfaulted half of the 7x7 unit cell, "raised" regions mostly on the faulted half, and flat island structures with a 2x2 pattern of silicon adatoms. Island density vs coverage follows a growth exponent near 1, suggestive of i=0 behavior (stable nucleus contains a single atom), and the temperature dependence is relatively weak. From 600-900C, the islands are atomically flat CoSi2, and they form only at step edges following completion of a 1x1-RC ("ring-clusters") layer. Island density is now much lower and strongly temperature dependent with an activation energy of approximately 2.0eV.