Cathodoluminescence and electrical study of vertical GaN-on-GaN Schottky diodes with dislocation clusters

Abstract

Electrical properties of vertical Schottky diodes fabricated on GaN regrown on hydride vapor phase epitaxy GaN substrates are investigated. The deposition of Ni frames makes it possible to designate the dislocation locations by cathodoluminescence before the fabrication of diodes. Since the distribution of dislocations is inhomogeneous and arranged into clusters over the GaN substrates, diodes made on either areas free of dislocation-clusters or areas with dislocation-clusters have been studied. Both forward and reverse characteristics of diodes fabricated on GaN with different doping levels and dislocation densities have been investigated. It is shown that the reverse leakage is not sensitive to the presence of dislocation clusters. On the other hand, there is a dispersion of reverse leakage which increases in diodes grown on substrates having larger mean dislocation density. The results also demonstrate that a critical maximum distance of around 100 µm between active defects triggers larger reverse leakage currents.