NEW MECHANISM OF FORMATION OF STACKING-FAULTS IN GE/(001)SI HETEROSTRUCTURES

Initial stages of misfit relaxation process in Ge epitaxial films grown in two-dimensional (layer-by-layer) mode on Si(001) have been investigated by high-resolution transmission electron microscopy. Special emphasis is placed on the dislocation interactions leading to rearrangements in a non-equilibrium dislocation network driven by elastic interaction between parallel 60 degrees dislocation segments. One of the dislocation reactions between closely spaced misfit segments which cannot combine to form a 90 degrees pure edge dislocation is analysed in detail. On the basis of our experimental observations, we propose a model for the formation of stacking faults in heterostructures. We discuss the energetics of various dislocation reactions involved and splitting of 60 degrees dislocations to create stacking faults.