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 10(4), 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.