Mechanisms of generation and atomic structure of defects in III-nitrides epitaxial systems for device applications

High resolution electron microscopy was applied to study the atomic structure of defects (dislocations, stacking faults, grain boundaries and nanopipes) and the mechanisms of their generation in III-nitrides epitaxial layers grown by MOVPE on sapphire. Formation of vertical boundaries in epitaxial layers was often associated with specific defects at the interface with a substrate. Dislocation generation and annihilation were shown to be mainly growth-related processes and, hence, can be controlled by the growth conditions, especially during the first growth stages.