Switching behavior and forward bias degradation of 700V, 0.2a, β-Ga₂O₃ vertical geometry rectifiers

We report the switching recovery characteristics of large area (contact dimension 0.04 × 0.04 cm²) vertical geometry β-Ga₂O₃ Schottky rectifiers, consisting of Si-doped epitaxial layers on conducting bulk substrates. Devices that were switched from forward current of 0.225 A to reverse off-state voltage of −700 V in an inductive load test circuit showed a recovery time (t_rr) of 82 ns, with a reverse recovery current (I_rr) of 38 mA and dI/dt of −2.28 A. μsec⁻¹. This shows the potential of Ga₂O₃ rectifiers for power switching applications, provided effective thermal management schemes can be implemented. Devices deliberately tested to failure under forward bias conditions exhibit delamination and cracking of the Ni/Au contact and underlying epitaxial Ga₂O₃ due to the low thermal conductivity of the Ga₂O₃. This failure mode is different to that under high reverse breakdown conditions, where pits formed by material failure under the high field generated at the edge of the rectifying contact occurs.