The suppression of dark current for achieving high-performance Ga2O3 nanorod array ultraviolet photodetector

Gallium oxide (Ga 2 O 3 ) is a promising candidate for next-generation solar-blind photodetectors (PDs) because of its large bandgap of 4.9 eV. Its single-crystal nanorod structure improves its photoelectric performance, which promotes carrier transformation and separation. However, Ga 2 O 3 nanorods fabricated by the hydrothermal method have many oxygen vacancies, which largely enhance the dark current and reduce the on/off ratio of PDs, restricting application of such devices. Therefore, in this paper, dual strategies are applied to reduce the dark current of a metal–semiconductor–metal-structured Ga 2 O 3 nanorod PD fabricated by the hydrothermal method. Through these dual strategies, which include annealing treatment and the application of a polymethyl methacrylate (PMMA) coating, the dark current of the PD is reduced from 1.34 × 10 −7 to 2.04 × 10 −9 A at 1 V, resulting in the on/off ratio of the PD reaching as high as 3.24 × 10 4 . Besides, the responsivity and detectivity of the device reach 1.73 A/W and 2.53 × 10 12 Jones respectively, which represents better performance than those of other reported Ga 2 O 3 nanorod array PDs. Results have shown that the new strategy adopted can greatly improve the performance of Ga 2 O 3 -based ultraviolet photodetectors.