TEM characterisation of defects, strains and local electric fields in AlGaN/InGaN/GaN structures

This paper describes how transmission electron microscopy (TEM) can be used to study the structure and electronic properties of threading defects in GaN structures. A combination of TEM and large angle convergent beam electron diffraction (LACBED) is used to examine dislocations and nanopipes, and to show that migration of dislocations in epitaxially overgrown material is correlated to local shear strains and grain rotations. It is shown how electron holography (EH) can be used to examine in-plane electric fields, and, in particular, the charge on threading edge dislocations.