New insights into the microscopic motion of dislocations in covalently bonded semiconductors by in-situ transmission electron microscope observations of misfit dislocations in thin strained epitaxial layers

By in-situ annealing of metastably strained (Si)/GexSi1−x/Si heterostructures in a transmission electron microscope, it is possible to directly observe and measure misfit dislocation propagation velocities. These measurements correspond to different regimes than conventional measurements of dislocation velocities in bulk Ge and Si, as in the present experiments motion at extremely high resolved applied (lattice-mismatch) shear stresses, of the order 1 GPa, and very low propagating dislocation lengths, 10 to 100 nm, is studied. This typically ensures that dislocation motion in the kink non-collision regime is observed, as opposed to the kink collision regime generally assumed in bulk measurements. By variation of the GexSi1−x/Si interface orientation, it is also possible to study the motion of total versus partial dislocations.