Synergistic photovoltaic-pyroelectric coupling in a Ga₂O₃/BaTiO₃ heterojunction for highly sensitive solar-blind ultraviolet photodetection

Ga₂O₃-based solar-blind ultraviolet photodetectors are promising for low-background ultraviolet (UV) sensing but remain limited by the trade-off between sensitivity and effective transient photoresponse. Here, a Ga₂O₃/BaTiO₃ (BTO) heterojunction photodetector is developed to enable highly sensitive, self-powered detection of transient optical events through the synergistic coupling of photovoltaic and pyroelectric effects. Owing to the type-II band alignment and the spontaneous polarization of BTO, the device delivers an ultralow dark current on the order of 10⁻¹³ A, a photo-to-dark current ratio exceeding 10⁶, and a specific detectivity of 2.63 × 10¹³ Jones. Under zero-bias and low-bias conditions, light-induced pyroelectric polarization modulation generates giant bipolar transient current pulses, contributing significantly to the self-powered photoresponse. Furthermore, the pyroelectric field also dynamically enhances interfacial carrier separation, thereby amplifying the overall photoresponse. This work offers a promising route toward intelligent solar-blind optoelectronic systems integrating event-driven sensing, self-powered operation, and hardware-level information security.