Focused Ion Beam Exposed Zinc Acetate Films for Preparation of Highly Sensitive Ultraviolet Photodetectors

Metal–semiconductor–metal (MSM) ultraviolet (UV) photodetectors have been widely studied owing to their advantages such as ease of preparation, high responsivity, and low costs; however, due to the high overlap between the light absorption layer and electron channel, the sensitivity of UV photodetectors needs to be improved. In this study, the direct generation of zinc oxide nanowires (ZnO NWs) with short lengths by focused ion beam (FIB) exposure of spin-coated zinc acetate films was observed for the first time. The bottoms of the short ZnO NWs were in contact with each other while the tops were independent of each other, which separated the light absorption layer of the UV photodetector from the electron channel, thereby effectively reducing the dark current of the UV photodetector and improving its sensitivity. A high ON/OFF ratio of 13 447 was achieved for the UV photodetector based on the as-prepared short ZnO NWs, and a high responsivity and specific detectivity were obtained, with a value of 25.33 A/W and
$3.24\times 10^{{13}}$
Jones, respectively. To optimize the response characteristics of the UV photodetector, the as-prepared short ZnO NWs were annealed at 350 °C and used as the seed layer to hydrothermally grow ZnO NWs with the bottoms not in contact with each other. This UV photodetector achieved an ON/OFF ratio of 28 378, a responsivity of 209.27 A/W, and a specific detectivity of
$1.4\times 10^{{14}}$
Jones. We directly prepared short ZnO NWs using FIB to achieve highly sensitive UV detection for the first time, offering new ideas and approaches for the design and preparation of high-performance UV photodetectors.