A Comparison of Two Epitaxial Formation Mechanisms in the SiGe System

Abstract

AbstractTwo epitaxial growth mechanisms and the resulting defect generation have been examined. The first involves standard growth by molecular beam epitaxy (MBE), while the second employs wet oxidation to form a Ge-rich epilayer from an initially amorphous film. The MBE-grown high Ge content layers evolve by island coalescence, while the oxidationproduced high Ge content layers form by a Ge exchange mechanism below a contamination layer, which results in a more uniform epitaxial layer. Thus, the resulting threading dislocation, stacking fault and twin densities, along with the surface roughness can be quite different. Results also indicate a high misfit dislocation density limited to the Si/SiGe interface and a strain redistribution into the Si substrate for the oxidation-produced epilayers.