Vertical GaN power rectifiers: interface effects and switching performance

Abstract

The emergence of free-standing GaN substrates enables the development of vertical GaN-on-GaN devices with high-power ratings and high frequencies. The Schottky interface plays an important role in determining the current transport mechanisms and the forward/reverse electrical performance of the vertical GaN Schottky barrier diodes. Moreover, given its direct bandgap and ultrashort minority carrier lifetime, it is of particular interest and importance to evaluate the fast switching performance of the vertical GaN power rectifiers. In this paper, we discuss the technology, physical mechanisms and characterizations of vertical GaN power rectifiers with high-quality interfaces and fast switching performances, including: (a) accurate characterization and carrier transport mechanisms of the Schottky interface; (b) Schottky interface engineering with optimized post-metallization annealing and a tunneling-enhancement layer; (c) fast reverse recovery performance that is characterized by high-speed board-level tests. The investigations and analysis on the interface effects and switching performance of the vertical GaN power rectifiers are valuable for high-efficiency and high-frequency power electronics applications.