High-Performance Self-Driven Solar-Blind Ultraviolet Photodetectors Based on HfZrO₂/β-Ga₂O₃ Heterojunctions

Ga₂O₃ is a wide-bandgap semiconductor that has shown great potential for application in solar-blind ultraviolet (UV) photodetectors. However, the responsivity and detectivity of Ga₂O₃-based self-driven solar-blind UV photodetectors are insufficient for practical applications at present because of the limited separation of photogenerated carriers in the devices. In this work, Hf_0.5Zr_0.5O₂/β-Ga₂O₃ heterojunction-based self-driven solar-blind UV photodetectors are constructed by combining ferroelectric Hf_0.5Zr_0.5O₂ (HfZrO₂) material with Ga₂O₃, taking advantage of the ultrawide bandgap of HfZrO₂ and the favorable II-type energy band configuration between both. Upon optimization, a HfZrO₂/β-Ga₂O₃ heterojunction-based UV photodetector with a HfZrO₂ layer thickness of 10 nm is shown to provide remarkable responsivity (R = (14.64 ± 0.3) mA/W) and detectivity (D* = (1.58 ± 0.03) × 10¹² Jones), which are much superior to those of a single Ga₂O₃-based device toward 240 nm light illumination. Further, the device performance is adjustable with varying poling states of HfZrO₂ and shows substantial enhancement in the upward poling state, benefiting from the constructive coupling of the ferroelectric depolarization electric field in HfZrO₂ and the built-in electric field at the HfZrO₂/β-Ga₂O₃ interface. Under illumination of weak light of 0.19 μW/cm², the upward poled device shows significantly enhanced R (52.6 mA/W) and D* (5.7 × 10¹² Jones) values. The performance of our device surpasses those of most previously reported Ga₂O₃-based self-driven photodetectors, indicating its great potential in practical applications for sensitive solar-blind UV detection.