Properties and performance of devices with epitaxial layers of the GeSi or GaAsInP systems are highly sensible to dislocations. The project aims to study dislocation nucleation and propagation under stresses different from the misfit stress by application of a load opposite to the misfit stress. Thus different dislocation types can be produced that move with different velocities at tensile or compressive stresses. TEM methods will be used to identify dislocation types. The distance dislocations move during annealing will be measured by double etching or using the scanning optical microscope in Nomarski mode. Experimental data will be fitted by a model that contains the stress fields arising from the misfit stress the back load, the stacking fault and the indentation.
An aim of especial technological interest is to see if stress conditions exist at which no dislocation nucleation or motion occurs. Those conditions can be used for processing of real device structures.