Line and point defect reductions in thin GaN epilayers with single and double in situ SiNx nanonetworks on sapphire substrates grown by metal-organic chemical vapor deposition were studied by deep-level transient spectroscopy, augmented by X-ray diffraction, and low-temperature photoluminescence . All samples measured by deep-level transient spectroscopy at 80 to 400K exhibited trap A (peak at about 325K) with an activation energy of 0.55 to 0.58eV, and trap B (peak at about 155K) with an activation energy of 0.21 to 0.28eV. The concentrations of both traps were much lower for layers with SiNx nanonetwork compared to the reference sample. The lowest concentration was achieved for the sample with 6min deposition SiNx nanonetwork, which was also lower than that for a sample prepared by conventional epitaxial lateral overgrowth. In concert with the deep-level transient spectroscopy results, photoluminescence and X-ray diffraction line-widths were reduced for the samples with SiNx network indicating improved material quality. Consistent trend among optical, structural, and deep-level transient spectroscopy results suggested that SiNx network could effectively reduce both point and line defects. Defect Reduction in GaN Epilayers Grown by Metal-Organic Chemical Vapor Deposition with in situ SiNx Nanonetwork. J.Xie, S.A.Chevtchenko, Ü.Özgür, H.Morkoç: Applied Physics Letters, 2007, 90[26], 262112