Vertical GaN-on-GaN p-n Diodes with 10-A Forward Current and 1.6 kV Breakdown Voltage

Abstract

The gallium nitride (GaN) material system has become one of the most promising material systems for high efficiency power switching applications due to its unique material properties, including a wide band gap, high critical electric field, and large mobility and saturation electron velocity. For high voltage, high current applications, vertical device structures on bulk GaN substrates are especially promising [1]. Although the ability to scale the devices to large absolute currents is critical for power electronics, to date the current-carrying capability of many demonstrated devices has fallen short of theoretical expectations due to non-idealities in device area scaling. High performance vertical GaN-on-GaN p-n diodes using N ion-implantation edge termination incorporating a partially-compensated layer were demonstrated to achieve breakdown voltages of 1.2 kV, and both the reverse and forward current densities were found to scale well with area [2]. In this work, a device structure designed for higher breakdown operation was explored, and devices with a range of areas were fabricated and tested under high-current drive conditions. Peak forward currents approaching 10 A at a forward voltage of 5.3 V were obtained for typical $550\ \mu \mathrm{m}$ diameter GaN-on-GaN p-n diodes having a breakdown voltage of 1.6 kV.