A detailed study was made of the luminescence at 3.42eV which was usually observed in a-plane epitaxial lateral overgrowth GaN, grown by hydride vapour-phase epitaxy onto r-plane sapphire. This band was related to the radiative recombination of excitons in a common a-plane GaN extended defect: the I1 basal stacking fault. Cathodoluminescence data showed that these stacking faults were mainly located in the windows and the N-face wings of the epitaxial lateral overgrowth GaN, and that they could be both isolated or organized into bundles. Time-integrated and time-resolved photoluminescence data, supported by a qualitative model, revealed not only the efficient trapping of free excitons by basal-plane stacking faults, but also some localization within the I1 stacking faults themselves. Measurements performed at room temperature showed that free excitons recombined efficiently, with rather long luminescence decay times of 360ps; comparable to those found in high-quality GaN epilayers. It was proposed that the I1 stacking faults played a role in the overall recombination mechanism of the excitons.

Exciton Localization on Basal Stacking Faults in a-Plane Epitaxial Lateral Overgrown GaN Grown by Hydride Vapor Phase Epitaxy. P.Corfdir, P.Lefebvre, J.Levrat, A.Dussaigne, J.D.Ganière, D.Martin, J.Ristić, T.Zhu, N.Grandjean, B.Deveaud-Plédran: Journal of Applied Physics, 2009, 105[4], 043102