Volume 88, Issue 10, 15 November 2000
Index of content:
- INTERDISCIPLINARY AND GENERAL PHYSICS (PACS 1‐41, 43‐47, 79, 81‐84, 89‐99)
88(2000); http://dx.doi.org/10.1063/1.1315615View Description Hide Description
Dislocation structures are presented for heterostructures before and after thermal processing. Cathodoluminescence has allowed nondestructive examination of bulk specimens, while transmission electron microscopy has been used to establish the details of the dislocation configurations. In each as-grown specimen the thickness of the layer was above its critical value, so 60° misfit dislocations were already present. It is shown that new pure edge, i.e., 90°, dislocations are formed at the interfaces by thermal processing at 1040 K. Their Burgers vectors are perpendicular to their 〈010〉 directions. Although individual 90° misfit dislocations are more effective relievers of strain than 60° ones, the self-energy for an array of such dislocations is higher and hence 60° misfit dislocations form first. A model of the formation of 90° edge misfit dislocations is proposed in which the climb of vacancy-producing jogs on pre-existing 60° dislocations leaves a trailing dislocation dipole.