Optical properties and structural investigations of (11-22)-oriented GaN/Al0.5Ga0.5N quantum wells grown by molecular beam epitaxy.

We have grown (11-22)-oriented GaN/Al0.5Ga0.5N quantum wells (QWs) using molecular beam epitaxy on GaN (11-22)-oriented templates grown by metal-organic vapor phase epitaxy on m-plane oriented sapphire substrates. The performance of epitaxial growth of GaN/Al0.5Ga0.5N heterostructures on the semi-polar orientation (11-22) in terms of surface roughness and structural properties, i.e., strain relaxation mechanisms is discussed. In addition, high resolution transmission electron microscopy reveals very smooth QW interfaces. The photoluminescence of such samples are strictly originating from radiative recombination of free excitons for temperatures above 100 K. At high temperature, the population of localized excitons, moderately trapped (5 meV) at low temperature, is negligible. [ABSTRACT FROM AUTHOR]