Effect of Oxygen Plasma on β-Ga₂O₃ Deep Ultraviolet Photodetectors Fabricated by Plasma-Assisted Pulsed Laser Deposition

We fabricated metal–semiconductor–metal-structured β-Ga 2 O 3 photodetectors using a plasma-assisted pulsed laser deposition system with various oxygen plasma radio frequency (RF) powers ranging from 0 to 100 W. All optoelectronic properties of the material were enhanced as the RF power increased. β-Ga 2 O 3 photodetector with RF power of 100 W showed the best optoelectronic characteristics, such as photoresponsivity of 0.39 A/W, external quantum efficiency of 192.61%, and detectivity of 9.09 × 10 13 cm Hz 1/2 /W. In addition, photo-switching analysis revealed the fastest photoresponse speeds (1.46 and 0.21 s) for on/off switching. These results originate from the decrease in the oxygen vacancy defect concentration in the β-Ga 2 O 3 films by the oxygen RF power. Our results suggest that β-Ga 2 O 3 photodetectors fabricated with oxygen plasma can optimize and improve the photodetection performance and can be applied for future deep ultraviolet detectors.