It was shown that strained-layer hetero-epitaxial systems could serve as model systems for the study of dislocation energetics and kinetics in semiconductors, via the introduction of strain-relieving misfit dislocation arrays. Such structures permitted fundamental dislocation properties to be studied at carefully controlled stresses of 107 to 109Pa. One parallel strain relaxation mode in strained heterostructures was coherent islanding or surface roughening of the epitaxial layer. This mechanism acted both in competition and in cooperation with the injection of misfit dislocations, and provided a further degree of control for the study of the fundamental energetic and kinetic properties of dislocations. By using ultra-sensitive in situ wafer curvature measurements of stress during the molecular beam epitaxial growth of GexSi1-x/Si heterostructures, the relative contributions of surface roughening and dislocation injection to strain relaxation could be qualitatively and quantitatively assessed. In addition, a new strain-stabilized morphology, the so-called quantum fortress, was identified during Ge0.3Si0.7/Si(100) hetero-epitaxy. This involved cooperative island nucleation around shallow strain-relieving pits.

Interaction Between Surface Morphology and Misfit Dislocations as Strain Relaxation Modes in Lattice-Mismatched Heteroepitaxy. R.Hull, J.Gray, C.C.Wu, S.Atha, J.A.Floro: Journal of Physics - Condensed Matter, 2002, 14[48], 12829-41