Oxygen Stoichiometry Engineering in P‐Type NiOx for High‐Performance NiO/Ga2O3 Heterostructure p–n Diode

Abstract

P‐type NiOx is employed for the fabrication of NiO/Ga2O3 p–n diode. Addressing the challenge of low hole mobility in NiOx, an extensive investigation into the impact of oxygen stoichiometry engineering in NiOx is conducted. The meticulous optimization of the O2/Ar ratio to 30% during the sputtering process results in significant improvements, notably achieving enhanced hole mobility of 1.61 cm2 V−1 s. It leads to a low specific on‐resistance of 2.79 mΩ cm2 and a high rectification ratio of ≈1011, underscoring the efficacy of recombination transport mechanism driven by enhanced hole mobility. Detailed band alignment analysis between NiOx and Ga2O3 reveals a small band offset, with a valence band offset of 2.47 eV and a conduction band offset of 1.70 eV. It suggests a tailored modification of band alignment through the engineering the oxygen stoichiometry in NiOx, facilitating enhanced recombination conduction. The device exhibits a superior breakdown voltage (Vb) of 2780 V and a notable Baliga's figure of merit (BFOM) of 2.77 GW cm−2, surpassing the SiC unipolar figure of merit. The insights gained from this work are expected to inform future designs and optimizations of high‐performance Ga2O3 electronic devices.