A -plane GaN epitaxial lateral overgrowth structures: Growth domains, morphological defects, and impurity incorporation directly imaged by cathodoluminescence microscopy

Abstract

The distinctly different growth domains of a-plane epitaxial lateral overgrown GaN on stripe masks oriented along [011̱0] direction were directly visualized by highly spatially and spectrally resolved cathodoluminescence microscopy. Clear cut microscopic regions dominated by differing individual peak wavelengths originating from either basal plane stacking faults, prismatic stacking faults, impurity related donor-acceptor pair or (D0,X) emission are explicitly correlated to the different growth domains. The luminescence in the domains grown in [0001] direction over the mask [epitaxial lateral overgrown wings] is dominated by the intense and sharp (D0,X) emission at 3.471eV. Here, no luminescence originating from morphological defects is found over several micrometers. This evidences the excellent material quality of the a-plane GaN, which is fully relaxed at the surface of the wings.