Vertical diodes on n-type β-Ga2O3 using p-Cu2O for heterojunction formation and edge termination

Abstract

Lack of viable p-type doping in ultra-wide bandgap β-Ga2O3 necessitates the use of p-type materials to form p–n heterojunction diodes (HJDs). This study demonstrates a comparative electrical performance analysis of vertical heterojunction devices using p-type Cu2O layers such as junction termination extension-Schottky barrier diodes (JTE-SBDs), p–n HJDs, and junction barrier Schottky diodes (JBSDs), along with control SBDs and SiO2 field plate (FP) SBDs. Through electrical characterization and TCAD simulations, we show that the JTE-SBD gives the best performance parameters with a 2.5× increase in breakdown voltage (Vbr = 656 V) with nearly matched differential specific on-resistance (Ron,sp = 1.73 mΩ cm2) compared to the control SBD due to improved edge electric field management, better than the FP-SBD and the JBSD, and without Ron,sp degradation observed in series resistance-limited HJD devices. The JTE-SBD demonstrates a Baliga's figure of merit of 0.24 GW/cm2. The near-unity ideality factors and low turn-on voltages of the p-Cu2O-based diodes further underscore its potential for enhancing β-Ga2O3 high-power diode performance, such as through effective edge electric field management shown through the JTE-SBDs in this work.