Elucidation of the correlation between atomic-level defects in GaN nanoparticles and photoluminescence properties by NMR, XRD and TEM

We present evidence from X-ray diffraction data that chemical shift changes observed in the 71Ga nuclear magnetic resonance spectrum of polycrystalline 15N-labeled GaN originate from crystal structure defects on the nearest neighbor atomic-level and are unlikely to be due to electronic effects from conduction band electrons (Knight shift). Nuclear magnetic resonance data (15N and 71Ga) suggests that these structural defects are caused by nitrogen-deficiency of the material. For Ga15N prepared by the reaction of 15N-labeled ammonia with different gallium precursors we observe a strong correlation between band edge related photoluminescence and the presence of nitrogen-deficient material in the sample. Quenching of photoluminescence by structurally bound protons has been observed by 1H nuclear magnetic resonance spectroscopy.

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