Surface recombination in GaN and ZnO crystals was comparatively investigated using steady-state and time-resolved photoluminescence (PL) measurements. The measurements were performed for various surface orientations (+c, −c, and m-plane surfaces), and the measured PL intensity and lifetime showed distinct dependence on the surface orientation. The dependence clearly indicates that the surface recombination rate is modified by the effects of surface band bending. The results were also verified by numerical analysis using a rate equation model considering the diffusion of photoexcited carriers and their recombination processes on the surface and inside the crystal.
GaN-based UV Schottky-type (ST) LEDs were fabricated using GaN layers grown by molecular beam epitaxy (MBE). Red, green, and blue (RGB) pixels were fabricated using the UV-LEDs and RGB phosphors. Surface modification led to the reduction in reverse-bias leakage current and improved forward-bias characteristics. It was found that the ideality factor, n, was improved with increasing breakdown voltage in the reverse-bias range. We believe that the improvement is due to the reduced number of threading-dislocation (TD)-related leakage paths. The effect of the point defects around the TDs on light emission was reduced by the surface modification because the number of current paths around the TDs was reduced.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.