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

Prospective optical properties were demonstrated for nearly stacking fault-free m -plane GaN homoepitaxial films grown by metal organic vapor 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 31 arcsec for the (10 1- 0) diffraction with 〈0001〉 azimuth and 48 arcsec for the (10 1- 2) diffraction. Threading dislocation densities were lower than 5× 106 cm-2. The film surfaces exhibited atomically flat morphology with well-aligned monolayer steps. Lowerature photoluminescence (PL) spectra exhibited polarization-dependent well-resolved bound and free exciton emission lines, and a characteristic π (k⊥c,Ec) -polarized PL line was also observed. Roomerature effective PL lifetime of the free exciton peak increased with increasing supply ratio of ammonia to trimethylgallium, and a record long value for m -plane GaN (268 ps) was obtained.