PtTe₂/Ga₂O₃ショットキー接合電界効果トランジスタにおける光誘起枯渇層変調による太陽盲紫外検出

The solar-blind phototransistor is a three-terminal device capable of substantially suppressing dark current and reducing noise solely through gate-voltage modulation. In this work, we report a top-gate β-Ga₂O₃ metal-semiconductor field-effect transistor employing a semimetal PtTe₂ gate that forms a dielectric-free van der Waals (vdW) Schottky contact with the channel. The corresponding transistor exhibits a minimal hysteresis of 80 mV, an extremely low OFF-state current of ≈10 fA, and an ON/OFF current ratio exceeding 10⁸. The phototransistor demonstrates excellent device performance in terms of a record-high photo-to-dark current ratio of 1.13 × 10⁹, a high responsivity of 6.75 × 10⁴ A/W, a large external quantum efficiency of 3.3 × 10⁷ %, and a high specific detectivity of 4.46 × 10¹⁵ Jones. These excellent characteristics are attributed to the top-gate-induced modulation of the depletion region, which suppresses dark current, and to the enhanced photocurrent generated by the synergistic response of the PtTe₂/β-Ga₂O₃ interface under illumination. The PtTe₂/β-Ga₂O₃ phototransistor provides a promising pathway toward high-responsivity and high-detectivity solar-blind optoelectronics.