Clusters of vacancies in Gallium Nitride grown by MOCVD

Abstract We investigate the formation and characteristics of vacancy clusters in Gallium Nitride (GaN) grown
by Metal-Organic Chemical Vapor Deposition (MOCVD). The research identifies vacancy-type defects,
particularly VGa-Hi complexes, using positron annihilation spectroscopy, in as-grown sample which are
transformed into vacancy clusters 2V Ga -2V N during low-energy electron beam irradiation. The study
employs photoluminescence (PL) and cathodoluminescence (CL) spectroscopy to analyze the
luminescence properties, demonstrating that yellow band (YB) and excitonic near-band-edge (NBE)
emission are greatly enhanced during the vacancy clustering process. The results indicate that the
luminescence spectra of the samples change significantly during electron beam irradiation,
highlighting the dynamic behavior of defects in GaN under different conditions. The dominant change
affecting the luminescence properties seems to be the elimination of a deep donor acting like a nonradiative
centrum. The experimental evidence suggests that this deep donor is V N . The findings
contribute to a deeper understanding of the role of nitrogen vacancy, vacancy complexes and clusters
in GaN, which is crucial for optimizing its applications in optoelectronic devices and their processing.