Parasitic p-n junctions formed at V-pit defects in p-GaN

The luminescent and recombination properties of V-pit defects in p-GaN(Mg) grown by metalorganic chemical vapor deposition (MOCVD) were studied by scanning electron microscopy (SEM) in the secondary electron, cathodoluminescence (CL), and electron beam induced current (EBIC) modes, combined with CL spectra measurements and EBIC collection efficiency measurements. Similar studies were performed on low-dislocation-density freestanding n-GaN crystals. For MOCVD p-GaN films, the SEM investigations were supplemented by capacitance-voltage, current-voltage, deep level transient spectroscopy analysis with Ni Schottky diode, and Ohmic contacts. These experiments show that V-pits in p-GaN increase the leakage current of Schottky diodes, as in n-GaN films and crystals. EBIC imaging and EBIC collection efficiency results suggest that in the region of V-pits, a parasitic p-n junction is formed. We also observe that, in V-pits, the CL spectra the contribution of the 3.2eV defect band is strongly enhanced compared to the 3eV blue CL band that dominates the spectra.

Automated summary

This study investigates the luminescent and recombination properties of V-pit defects in p-GaN(Mg) grown by MOCVD, as well as their impact on the leakage current of Schottky diodes. The results also suggest the formation of parasitic p-n junctions in the region of V-pits. Additionally, the increase in a 3.2eV defect band contribution in V-pits compared to the 3eV blue CL band is observed.