High-performance solar-blind ultraviolet photodetectors based on κ-Ga2O3 by water-assisted MOCVD epitaxy

Oxygen-related defects can provide photoconductive gain in gallium oxide (Ga 2 O 3 ) solar-blind ultraviolet photodetectors (UVPDs), but can also enhance dark-state carrier transport, low-frequency noise, and persistent photoconductivity (PPC). In this work, O 2 containing 10 ppm H 2 O is introduced during the metal-organic chemical vapor deposition (MOCVD) epitaxy of Ga 2 O 3 , enabling the water-assisted growth of κ -Ga 2 O 3 films on Si/AlN substrates. With the introduction of trace H 2 O, the full width at half maximum (FWHM) of the κ -Ga 2 O 3 (002) rocking curve is reduced from 0.68° to 0.49°, while the oxygen-defect-related component in the O 1s spectrum is decreased from 15.4% to 10.3%. The metal-semiconductor-metal (MSM) solar-blind ultraviolet photodetector fabricated from the film grown under humidified O 2 exhibits a dark current of 2.15 nA and a responsivity of 10.81 A W −1 at 5 V. Meanwhile, the rise/fall times are shortened from 1547/124 ms for the dry-O 2 -grown device to 875/18 ms. These results demonstrate that water-assisted growth improves the structural quality of κ -Ga 2 O 3 and reduces oxygen-related defects, thereby concurrently suppressing dark-state carrier injection, carrier fluctuations, and slow post-illumination carrier release. This work provides a viable route for the regulation of defects in Si-based κ -Ga 2 O 3 solar-blind UVPDs.