AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS1+NS-ThM

Paper SS1+NS-ThM10
Three-Dimensional SiGe Island Density on Si(001) and Morphology After Si Overgrowth@footnote 1@

Thursday, November 5, 1998, 11:20 am, Room 308

Session: Growth and Thin Films
Presenter: J.S. Sullivan, University of Wisconsin, Madison
Authors: J.S. Sullivan, University of Wisconsin, Madison
E. Mateeva, University of Wisconsin, Madison
H. Evans, University of Wisconsin, Madison
D.E. Savage, University of Wisconsin, Madison
M.G. Lagally, University of Wisconsin, Madison
Correspondent: Click to Email
Thin films of SiGe deposited on Si(001) can form three-dimensional (3D), coherently strained islands via a modified Stranski-Krastanov growth mode. Single films as well as highly ordered 3D superlattices with specific island sizes and densities may exhibit unique electronic and optoelectronic properties. In order to investigate how common process variables in epitaxial multiple-layer film growth influence 3D island density and morphology, we deposited SiGe films on Si(001) using low-pressure chemical vapor deposition and varied alloy composition, substrate temperature, and deposition rate. Films containing {105} faceted SiGe islands were overgrown with and embedded in Si at various substrate temperatures. Film growth and morphological evolution were monitored with in-situ, real-time reflection high-energy electron diffraction. Atomic force microscopy was performed ex-situ to characterize film morphology, and buried-island morphology was determined with cross-sectional transmission electron microscopy. The 3D island number density exhibits an Arrhenius-type dependence on substrate temperature, a power law relationship with deposition rate, and an inverse proportionality to Ge mole fraction in the alloy. Islands broaden during overgrowth and embedding due to thermally activated mass transport and Si interdiffusion; such that the {105} facets grow outward producing a (001) mesa at the apex. We will discuss our results in the context of simple thermodynamic and kinetic models and describe possible methods of obtaining and maintaining a specific size and size distribution of 3D islands. @FootnoteText@ @footnote 1@Supported by the NSF.