Breakdown capability of β-Ga 2 O 3 /GaN heterojunction-based vertical p-n power diodes with mesa edge termination (ET) was comprehensively investigated using TCAD simulation. With 5 μm β-Ga 2 O 3 drift layer, the ideal breakdown voltage (BV) of the heterojunction was 1.37 kV, while the BV of the reference device without effective mesa edge termination decreased dramatically to 300 V due to the electric field crowding at the device edge. Four mesa ET structures were investigated to mitigate the

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... lectric field crowding at the junction edge, including beveled mesa, step mesa, deeply etched mesa, and p-doped guard ring. Without effective ET, the peak electric field at the junction edge was ∼4.2 MV/cm at −300 V. By incorporating these ET techniques, the peak electric fields were reduced significantly to 0.73 MV/cm. Ideal BV of 1.37 kV was achievable using deeply etched mesa and guard ring ETs. The beveled mesa realized >80% of the ideal BV, while step mesa ET was less effective in alleviating the electric field crowding and only offered ∼ 40% of the ideal BV. The device BV can be further scaled by varying β-Ga 2 O 3 drift layer thickness. This work can serve as an important reference and guideline for developing high power high voltage β-Ga 2 O 3 based bipolar power devices. INDEX TERMS Edge termination, gallium oxide (Ga 2 O 3 ), heterojunction, p-n diode, wide bandgap (WBG) semiconductor.