It was shown here how transmission electron microscopy could be used to study the structures and electronic properties of threading defects in GaN structures. A combination of transmission electron microscopy and large-angle convergent beam electron diffraction was used to examine dislocations and nanopipes and demonstrate that the migration of dislocations in epitaxially overgrown material was related to local shear strains and grain rotations. It was also shown how electron holography could be used to examine in-plane electric fields, and especially the charges on threading edge dislocations.

TEM Characterisation of Defects, Strains and Local Electric Fields in AlGaN/InGaN/GaN Structures. D.Cherns: Materials Science and Engineering B, 2002, 91-92, 274-9