A Review on Reverse-Bias Leakage Current Transport Mechanisms in Metal/GaN Schottky Diodes

GaN and related nitride semiconductors have attracted considerable interest for use in solid-state light and high-power/-frequency devices. Fabrication of high-quality metal/GaN Schottky contacts is essential to ensure that GaN-based devices perform well. However, GaN Schottky contacts suffer from abnormally high reverse leakage currents that significantly reduce device performance. Hence, a comprehensive understanding of the reverse current transport mechanisms associated with GaN Schottky diodes is essential for reproducible and reliable fabrication of GaN-based devices. In this paper, several possible leakage current transport mechanisms in GaN Schottky devices are briefly reviewed. Poole–Frenkel and thermionic field emissions are generally responsible for the reverse leakage currents of metal/GaN Schottky diodes. In real-world devices, two transport mechanisms can simultaneously contribute to the reverse leakage current, and they must be distinguished to fully understand device performance. In particular, the temperature- and metal electrode-dependent current characteristics require careful and systematic analysis.