Heterojunction structure for suppressing dark current toward high-performance ZnO microrod metal-semiconductor-metal ultraviolet photodetectors

ZnO microrod metal-semiconductor-metal (MSM) photoconductive detectors have generally shown a high photoconductive gain but with a low detectivity owing to the high dark current. Fortunately, the dark current can be suppressed in reverse-biased heterojunctions. In this work, we have reported the fabrication of high-performance MSM ultraviolet photodetectors based on multilayer graphene oxide/ZnO microrod (MLGO/ZnO) heterojunctions. Structural, optical, and electrical properties studies have suggested that the ZnO microrods possessed a high crystalline quality but with a high concentration of defects, which led to a high dark current and low detectivity in the reference ZnO MSM photodetectors. Notably, the dark current has been substantially suppressed by more than 5 orders of magnitude in the MLGO/ZnO heterojunction MSM photodetectors owing to a high potential barrier formed at the MLGO/ZnO heterojunction interface. Finally, the responsivity and detectivity as high as 210 A/W and 3.0 x 10(14) Jones, respectively, have been achieved, which are higher than most of the state-of-the-art devices. The results reported in this paper provide a simple and cost-effective approach for the fabrication of high-performance MSM photoconductive detectors.