AVS 47th International Symposium
    Semiconductors Wednesday Sessions
       Session SC+EL+SS-WeA

Paper SC+EL+SS-WeA3
Critical Behavior of Epitaxial Si@sub 1-x@Ge@sub x@/Si(001) Islands

Wednesday, October 4, 2000, 2:40 pm, Room 306

Session: Semiconductor Alloys
Presenter: R.A. Budiman, University of Toronto, Canada
Authors: R.A. Budiman, University of Toronto, Canada
H.E. Ruda, University of Toronto, Canada
D.D. Perovic, University of Toronto, Canada
B. Bahierathan, University of Toronto, Canada
Correspondent: Click to Email
We study the island size distributions of three-dimensional Si@sub 1-x@Ge@sub x@/Si(001) islands of varying Ge fractions (x = 0.4-0.7) and thicknesses grown by ultrahigh vacuum chemical vapor deposition. The size distributions of the percolating islands obey the dynamic scaling hypothesis due to random percolation process, only in the small island limit. Morphologies of the islands strongly suggest a presence of Smoluchowski ripening mechanism, in which islands collide and ripen. We therefore combine random percolation and Smoluchowski ripening to analyze the size distributions. To understand the critical behavior of the islands as exhibited by their size distributions, we formulate a mean-field theory of coherently strained island formation by incorporating surface energy and strain relaxation. The resulting phase diagram shows that the island formation in Si@sub 1-x@Ge@sub x@/Si(001) is located near the critical region. Order parameter fluctuations can be estimated by calculating the curvature energy for such a system and we find that the strain fluctuation is indeed relevant to properly describe the island formation in the Si@sub 1-x@Ge@sub x@/Si(001) system.