Fabrication and Characterization of High-Voltage NiO/β-Ga2O3 Heterojunction Power Diodes

This work presents the fabrication and characterization of a high-performance vertical Nickel oxide (NiO)/Beta gallium oxide (beta-Ga2O3) heterojunction p-n diode. The heterojunction was fabricated by sputtering a p-NiO thin film onto an epitaxial n(-)-beta-Ga2O3 drift layer. The sputtered NiO, revealed to be polycrystalline, showed an improved crystallinity after annealed in an oxygen ambient, while a seamless contact with the underneath single crystalline beta-Ga2O3 was observed. A high hole concentration of 1-3 x 10(19) cm(-3) and an improved Ohmic contact were also obtained by the annealing process, as confirmed by the Hall and TLM measurements, respectively. A high breakdown voltage (V-B) of 1.4 kV and a low specific ON-resistance (R-on,R- sp) of 2.7 m Omega.cm(2) were simultaneously achieved for the fabricated diodes, yielding a superior Baliga's figure-of-merit (BFoM) of 0.73 GW/cm(2). From the temperature-dependent current-voltage (I-V) measurements, two carrier transport mechanisms, namely interface recombination and multistep tunneling, have been identified in the forward conduction of the NiO/beta-Ga2O3 heterojunction. The fast recovery property of the device, which was revealed by a double-pulse test, further confirmed the purposed carrier transport mechanisms.

Automated summary

In this work, a high-performance vertical NiO/beta-Ga2O3 heterojunction p-n diode was successfully fabricated, showing high breakdown voltage and low specific ON-resistance. Through optimized fabrication process, superior performance was achieved, contributing significantly to the development of power devices.