A Comprehensive Study of Reverse Current Degradation Mechanisms in Au/Ni/n-GaN Schottky Diodes

In this paper, we perform a comprehensive study on the reverse current degradation mechanisms in Au/Ni/n-GaN Schottky diodes based on an in-depth understanding on the defect-related current transport mechanisms. Instead of traditional Poole-Frenkel (PF) emission model, an extended bulk-limited PF transport process, including the compensation effect, is adopted to explain the variation of the PF current slope as a function of the stress time, which majorly takes place inside the depletion region near the neutral semiconductor side. Based on the electrostatic analysis, we develop a shallow donor-like defects model to address the current degradation kinetics, which states that the energetic electrons produced by Fowler-Nordheim tunneling can induce significant Joule heating effect during the subsequent drift move of field, and give rise to the formation of the donor-like defects, and in turn enhance the surface electrical field to cause a significant increase of the tunneling component, in good agreement with the emission microscope observations.