• Fabrication of vertical SnO/β-Ga2O3 heterojunction diode via RF reactive magnetron sputtering.
• Determination of type-II band alignment with valence and conduction band offsets of 2.65 eV and 0.75 eV, respectively.
• Enhanced reverse blocking characteristics with breakdown voltage of 1675 V and power figure of merit of 1.0 GW/cm² compared to Schottky barrier diode.
• TCAD simulation shows that SnO film depresses electric field crowding at the anode edge, indicating potential for high-performance power devices.