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

Ga 2 O 3 is a wide-bandgap semiconductor that has shown great potential for application in solar-blind ultraviolet (UV) photodetectors. However, the responsivity and detectivity of Ga 2 O 3 -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 0.5 Zr 0.5 O 2 /β-Ga 2 O 3 heterojunction-based self-driven solar-blind UV photodetectors are constructed by combining ferroelectric Hf 0.5 Zr 0.5 O 2 (HfZrO 2 ) material with Ga 2 O 3, taking advantage of the ultrawide bandgap of HfZrO 2 and the favorable II-type energy band configuration between both. Upon optimization, a HfZrO 2 /β-Ga 2 O 3 heterojunction-based UV photodetector with a HfZrO 2 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) × 10 12 Jones), which are much superior to those of a single Ga 2 O 3 -based device toward 240 nm light illumination. Further, the device performance is adjustable with varying poling states of HfZrO 2 and shows substantial enhancement in the upward poling state, benefiting from the constructive coupling of the ferroelectric depolarization electric field in HfZrO 2 and the built-in electric field at the HfZrO 2 /β-Ga 2 O 3 interface. Under illumination of weak light of 0.19 μW/cm 2, the upward poled device shows significantly enhanced R (52.6 mA/W) and D * (5.7 × 10 12 Jones) values. The performance of our device surpasses those of most previously reported Ga 2 O 3 -based self-driven photodetectors, indicating its great potential in practical applications for sensitive solar-blind UV detection.