DC and dynamic switching characteristics of field-plated vertical geometry β-Ga₂O₃ rectifiers

Reverse breakdown voltages larger than 1 kV have been reported for both unterminated Ga₂O₃ vertical rectifiers (1000- 1600 V) and field-plated Schottky diodes (1076-2300 V) with an epi thickness of 8-20 μm. If the doping is in the 10¹⁶ cm^-3 range, the breakdown is usually in the 500-800V regime. Furthermore, the switching characteristics of discrete Ga₂O₃ vertical Schottky rectifiers exhibited reverse recovery times in the range of 20 to 30 ns. Large area (up to 0.2 cm²) Ga₂O₃rectifiers were fabricated on a Si-doped n-Ga₂O₃ drift layer grown by halide vapor phase epitaxy on a Sn-doped n+ Ga₂O₃ (001) substrate. A forward current of 2.2 A was achieved in single-sweep voltage mode, a record for Ga₂O₃ rectifiers. The on-state resistance was 0.26 Ω·cm² for these largest diodes, decreasing to 5.9 × 10^-4 Ω·cm² for 40x40 μm² devices. We detail the design and fabrication of these devices. In addition, an inductive load test circuit was used to measure the switching performance of field-plated, edge-terminated Schottky rectifiers with a reverse breakdown voltage of 760 V (0.1 cm diameter, 7.85x10^-3 cm² area) and an absolute forward current of 1 A on 8 Μm thick epitaxial β-Ga₂O₃ drift layers. These devices were switched from 0.225 A to -700 V with t_rr of 82 ns, and from 1 A to -300 V with t_rr of 64 ns and no significant temperature dependence up to 125°C. There was no significant temperature dependence of t_rr up to 150°C.