Large critical field of Li-doped NiO investigated by p⁺-NiO/n⁺-Ga₂O₃ heterojunction diodes

Abstract Critical electric fields ( E C ) of lithium-doped p + -nickel oxide (NiO) were investigated by the capacitance ( C )–voltage ( V ) and current ( I )– V measurements using p + -NiO/n + -gallium oxide (Ga 2 O 3 ) heterojunction diodes. The E C was estimated by device simulations using the net acceptor concentrations ( N A ) obtained from C–V measurements and breakdown voltages obtained from reverse I–V characteristics. The E C of NiO depended on the N A of the NiO and ranged from 5.4 to 10.1 MV cm −1 . Large E C was obtained for high N A . NiO was confirmed to be one of the promising p-type oxides to realize high-power p-n heterojunction devices with Ga 2 O 3 due to the high E C .