A 1.86-kV double-layered NiO/β-Ga2O3 vertical p-n heterojunction diode

In this Letter, high-performance vertical NiO/beta-Ga2O3 p-n heterojunction diodes without any electric field managements were reported. The devices show a low leakage current density and a high rectification ratio over 10(10) (at +/- 3V) even operated at temperature of 400K, indicating their excellent thermal stability and operation capability at high temperature. Given a type-II band alignment of NiO/beta-Ga2O3, carrier transport is dominated by the interface recombination at forward bias, while the defect-mediated variable range hopping conduction is identified upon strong reverse electric field. By using the double-layer design of NiO with a reduced hole concentration of 5.1x10(17)cm(-3), the diode demonstrates an improved breakdown voltage (V-b) of 1.86kV and a specific on-resistance (R-on,R-sp) of 10.6 m Omega cm(2), whose power figure of merit (V-b(2)/R-on,R-sp) has reached 0.33GW/cm(2). The high breakdown voltage and low leakage current are outperforming other reported Ga2O3 based p-n heterojunctions and Schottky barrier diodes without field plate and edge termination structures. TCAD simulation indicates that the improved V-b is mainly attributed to the suppression of electric field crowding due to the decreased hole concentration in NiO. Such bipolar heterojunction is expected to be an alternative to increase the breakdown characteristics of beta-Ga2O3 power devices.