Dual-field plated β-Ga₂O₃ nano-FETs with an off-state breakdown voltage exceeding 400 v

The nature of ultra-wide energy bandgap (UWBG) semiconductors enables transistors to withstand large voltage swings, ensuring stable high-power and high-efficiency operation. The potential of UWBG β-Ga₂O₃ nano-field effect transistors (nano-FETs) has not been fully explored due to premature avalanche breakdown in these devices, despite their extremely high critical breakdown field. An exfoliated β-Ga₂O₃ nano-layer was fabricated into a depletion-mode nano-FET integrated with dual field-modulating layers to redistribute the electric field crowded around the drain edge of the gate electrode. A stepped-gate field-plate and a source-grounded field-modulating electrode were integrated into the planar β-Ga₂O₃ nano-FETs. Excellent output and transfer characteristics were demonstrated, i.e. a low subthreshold swing (95.0 mV dec^-1) and high on/off ratio (∼10¹⁰), achieving an ultra-high off-state three-terminal breakdown voltage of 412 V. The experimental results were compared with numerical simulations, confirming the efficacy of the dual-field plate structure. The introduction of multiple field-modulating plates into the UWBG β-Ga₂O₃ nano-FETs greatly increased the voltage swings to over 400 V, suggesting the possibility for small footprint power electronics.