Optical and electrical characterizations of the V-shaped pits in Fe-doped bulk GaN

The leakage current path in the vertical-type metal-semiconductor-metal structured device fabricated on a Fe-doped bulk GaN substrate with a V-shaped pit is investigated. Micro-Raman, micro-photoluminescence, and atomic force microscope show nonuniform distributions of the optical and electrical properties in the V-shaped pit. The distribution of carrier concentration is determined by the distributions of Si, O, and Fe impurities, which are further influenced by the incorporation efficiency of the corresponding impurities in the semi-polar growth facets. The mechanism of current leakage in a V-shaped pit is explained by the big difference between the resistance inside and outside the pit.