2.6 kV NiO/Ga2O3 Heterojunction Diode with Superior High-Temperature Voltage Blocking Capability

In this study, we demonstrate an effective edge termination for vertical NiO/β-Ga2O3 heterojunction diodes using a continuous p-NiO film as Junction Termination Extension (JTE). The JTE can spread out the edge electric field and reduce the peak electric field of the devices. The annealing process was optimized to suppress leakage current and increase Ion/Ioff ratio up to ~10¹⁰. The record high breakdown voltage of 2.66 kV in heterojunction diodes with uniform distribution of leakage current was achieved. Analysis of temperature-dependent reverse current revealed that the reverse leakage mechanism of the devices is dominated by Poole-Frenkel emission. The breakdown voltage of 1.77 kV at 250 °C shows remarkable high-temperature voltage blocking capability of the devices and validates the great potential of NiO/β-Ga2O3 diodes for high-temperature and high-voltage power electronic applications.

I. Introduction

Beta-gallium oxide (β-Ga₂O₃) has emerged as a promising candidate material for high-efficiency power switching applications under harsh operating conditions, including high voltage, high temperature and radiation, owing to its ultra-wide bandgap (~4.8 eV), high critical breakdown field (8 MV/cm), large Baliga’s figure-of-merit and high thermal stability[1]-[3]. In addition, high-quality and large-sized Ga₂O₃ single crystal substrates can be obtained by melt growth methods, which provides a guarantee for the large-scale production and commercialization of power devices based on Ga₂O₃ in the future.