Threading defect elimination in GaN nanowires

This study describes the elimination of threading dislocations (TDs) in GaN nanostructures. Cross-sectional transmission electron microscopy (XTEM) analysis reveals that the nominal [0001] line direction of a TD changes when it enters a GaN nanostructure and the dislocation then terminates at a sidewall facet. It is suggested that the driving force for this process is the reduction of dislocation line energy, and for a pure-edge dislocation, this TD elimination process can be accomplished simply by dislocation climb. This mechanism is active whenever a threading defect is in close proximity to a surface. Preliminary XTEM analysis of defects in AlGaN and InGaN core-shell growth onto GaN nanostructures is also shown. Although more work is required to improve the quality of core-shell InGaN epitaxial growth, nanostructures appear to offer a route to defect-free, nonpolar GaN-based devices.