Fast-Response Amorphous Ga₂O₃ Solar-Blind Ultraviolet Photodetectors Tuned by a Polar AlN Template

Gallium oxide (Ga₂O₃) is an emerging semiconductor for advanced optoelectronic applications owing to its suitable bandgap and advantageous electronic characteristics. While amorphous Ga₂O₃ is highly desired for low-cost and large-scale device application, it suffers from high dark current and slow response speed for practical ultraviolet photodetection. Here we integrate a polar aluminum nitride (AlN) template with amorphous Ga₂O₃ to fabricate a fast-response metal semiconductor metal (MSM) photodetector. It is revealed that the carrier transport and device performance strongly depend on the polarization direction of the AlN template. With a downward polarization from an Al-polar AlN layer, the Ga₂O₃ photodetector achieves an optimized performance with a lower dark current of 0.015 nA, a higher photo-to-dark current ratio of 10⁴, a faster response speed of 31 ms and a recovery time of 22 ms. This study demonstrates an effective route of engineering carrier transport via the external spontaneous polarization for fabricating high-performance solar-blind photodetectors.