A Reliability Study on the Effects of HTOL and High-Current Density Stress Testing on Commercial-Grade Vertical N-Type PD/GAN Schottky Diodes

Traditional silicon-based power electronics have approached their performance limits for high-power electronic applications. The U.S. Navy is actively pursuing the implementation of wide bandgap (WBG)semiconductor materials to realize reliable devices for use in high-power, high-current, and high-voltage applications. Gallium nitride (GaN) is a promising candidate for these applications due to its inherent material properties, and recent efforts to produce high quality bulk GaN have begun to enable the production of commercial-grade devices. However, much is still unknown regarding the reliability of GaN devices, especially Schottky diodes, which are often affected by issues involving barrier height inhomogeneity (BHI). First, a stress testing system capable of taking in-situ current-voltage-temperature (I-V-T) measurements while applying electrical stress was constructed. Next, a sample of commercial-grade vertical n-type palladium/gallium nitride(Pd/GaN) Schottky diodes were subjected to a series of step current and constant current stress tests. Current densities above 1.3 kA/cm^2 were achieved. Finally, the effects of electrical stress on material properties were observed through comparison of pre-, post-, and in-situ I-V-T data. The in-situ I-V-T measurements enabled degradation to be observed as a function of stress time. Results show that significant degradation to the material properties of the Schottky diodes occurs within the first few hours of stress testing