Anisotropic extended misfit dislocations in overcritical SiGe films by local substrate patterning

Abstract

In this work we will show how local substrate patterning leads to a long range controlled propagation of dislocations in SiGe films grown on Si(001) substrates. Dislocations preferentially nucleate in the inhomogeneous strain field associated with the patterned pits, and then partialize on the local (111) surfaces which form the pit sidewalls. The resulting V-shaped defects extend for several microns and effectively block the propagation of randomly nucleated dislocations which propagate in the perpendicular direction. The surface morphology and strain fields associated with the extended defects have been characterized by atomic force microscopy and μRaman spectroscopy, and the defects have been directly observed with high resolution transmission electron microscopy.

Dislocation Analysis in SiGe Heterostructures by Large-Angle Convergent Beam Electron Diffraction

“…This concept works quite well; for example, Gatti et al [51] demonstrated this by employing {111} facets in the form of trenches along the [110] directions on (001) substrates as preferential nucleation centers for dislocation loops. Similar concepts are demonstrated by Grydlik et al [52] or Bollani et al [53], where {111} faceted pit structures are employed. Here, TEM investigations prove that the compressive strained SiGe layer on the {111} facets leads to stacking faults.…”