kV-class Ga₂O₃ vertical rectifiers fabricated on 4-in. diameter substrates

100 μm diameter Schottky and heterojunction vertical Ga₂O₃ rectifiers were fabricated on ∼10 μm thick drift layers grown on 4-in. diameter bulk Ga₂O₃ substrates. The uniformity of breakdown voltage was measured on 50 heterojunction devices over a quadrant of the wafer and showed variations from 2 to 8.5 kV, with the higher range correlating with thicker drift layers and lower background doping levels. The median breakdown voltage was ∼6 kV in this area and ∼3 kV in the areas with thinner drift layers and higher doping levels. By contrast, Schottky rectifier breakdown voltages were 0.7–1.8 kV. The minimum on-resistances were in the range of 4–7 mΩ cm² for Schottky barrier diodes and 5–9 mΩ cm² for heterojunction diodes, with on-voltages of 0.6–0.75 V for the former and 1.7–1.75 for the latter. The results show the promise of large diameter Ga₂O₃ substrates in providing high numbers of kV-class rectifiers for electric vehicle charging and other applications.