Strain relaxation mechanisms occurring during self-induced growth of nitride nanowires were investigated by in situ reflection high-energy electron diffraction and ex situ high-resolution transmission electron microscopy. Epitaxial GaN nanowires nucleated on an AlN buffer layer under highly nitrogen-rich conditions via the initial formation of coherently strained three-dimensional islands according to the Volmer–Weber growth mechanism. The epitaxial strain relief in these islands occurred by two different processes. Initially, strain was elastically relieved via several shape transitions. Subsequently, plastic relaxation takes place through the formation of a misfit dislocation at the GaN/AlN interface. At the same time, a final shape transition to fully relaxed nanowires occurs.

In situ Analysis of Strain Relaxation during Catalyst-Free Nucleation and Growth of GaN Nanowires. M.Knelangen, V.Consonni, A.Trampert, H.Riechert: Nanotechnology, 2010, 21[24], 245705