Dislocation climb in GaAs

The weak-beam technique of transmission-electron-microscopy is used to investigate dislocation climb in GaAs, a high supersaturation of point defects being introduced by electron irradiation in a high-voltage-electron-microscope. It is shown that, at room temperature, climb of dissociated a/2 <110> dislocations proceeds by nucleation of both Frank and perfect interstitial loops on the individual partials. Irradiation carried out at higher temperature (4500C) showed evidence for the interaction of the new loops with the non-parent partial, leading to climb of the total dislocation. Dislocations of α and β-type, i.e. of opposite edge character, exhibit the same climb mechanism. In this paper, the microscopic mechanism of dislocation climb is analysed and the relevance of this study to the understanding of the degradation of GaAs devices by climbing dislocations is considered