1-kV Sputtered p-NiO/n-Ga₂O₃ Heterojunction Diodes With an Ultra-Low Leakage Current Below $1~\mu$ A/cm²

Abstract

High performance NiO/β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> heterojunction pn diodes were realized by applying a sputtered p-type NiO film onto a lightly doped n-type β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> epitaxial layer. Taking advantage of the high barrier height against carriers within the pn heterojunction, the demonstrated device exhibited a high breakdown voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> ) of 1059 V without optimized electric field management techniques, and before breakdown the reverse leakage current density remained below 1 μA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Simultaneously, a relatively low specific on-resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> , <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sp</sub> ) of 3.5 mΩ · cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was achieved. The built-in potential of the heterojunction that determined by a capacitance-voltage (C-V) measurement was around 2.4 eV. As discussed in terms of the energy band diagram of a type-II heterojunction, the conduction band and valence band offsets at the NiO/β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hetero-interface were estimated to be 1.2 and 2.3 eV, respectively.