Convergent beam electron diffraction investigation of inversion domains in GaN

Abstract

Gallium nitride is of wurtzite or zincblende structure, therefore, it exhibits a polar character along many directions. Its growth on the surface of a non-polar substrate can lead to the formation of Inversion Domain Boundaries (IDBs) related by the disappearance of the centre of symmetry. Inversion domains and other defects such as prismatic stacking faults and nanopipes form closed domains. In this work we have used convergent beam electron diffraction (CBED) to determine the polar character of closed domains in GaN layers grown on various substrates. It was found that such domains on top of 6H SiC are non-polar prismatic stacking faults, whereas inversion domains may form directly on top of (0 0 0 1) sapphire or (1 1 1) silicon.