In-situ direct measurement of activation energies for the generation of misfit dislocations in the InGaAs/GaAs (001) system

In-situ X-ray topography (XRT) studies of misfit dislocation generation and movement in epitaxial InGaAs strained-layer structures on (001) GaAs are described. Examination of the changes in dislocation structure during a series of successive post-growth in-vacuo sample anneals has, for the first time, yielded activation energies of 0.7 and 0.8 eV for the formation of alpha- and beta-misfit dislocations (MDs) by the initial glide of substrate threading dislocations (TDs) in the InGaAs epilayer. The introduction of MDs by this method is supplemented by the presence of an additional MD generation process. The activation energy for this is found to be comparable to that required to initiate the glide of a TD. The XRT studies have also confirmed the existence of MD cross-slip events, where alpha to beta cross-slip was found to have an activation energy of 1.2 eV and to be much more common than the reverse beta-alpha cross-slip process. (C) 1998 Elsevier Science B.V.