Prospective optical properties were demonstrated for nearly stacking fault-free m-plane GaN homo-epitaxial films grown by metal organic vapour phase epitaxy on the m-plane freestanding GaN substrates. Values of full width at half maximum of X-ray rocking curves were close to the substrate values being 31arcsec for the (10•0) diffraction with <00•1> azimuth and 48arcsec for the (10•2) diffraction. Threading dislocation densities were lower than 5 x 106/cm2. The film surfaces exhibited atomically flat morphology with well-aligned monolayer steps. Low-temperature photoluminescence  spectra exhibited polarization-dependent well-resolved bound and free exciton emission lines, and a characteristic polarized photoluminescence line was also observed. Room-temperature effective photoluminescence lifetime of the free exciton peak increased with increasing supply ratio of ammonia to trimethylgallium, and a record long value for m-plane GaN (268ps) was obtained.

Optical Properties of Nearly Stacking-Fault-Free m-Plane GaN Homoepitaxial Films Grown by Metal Organic Vapor Phase Epitaxy on Low Defect Density Freestanding GaN Substrates. S.F.Chichibu, H.Yamaguchi, L.Zhao, M.Kubota, K.Okamoto, H.Ohta: Applied Physics Letters, 2008, 92[9], 091912