Ultraviolet Photodetector Fabricated from 3D WO 3 Nanowires/Reduced Graphene Oxide Composite Material
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Ultraviolet Photodetector Fabricated from 3D WO3 Nanowires/Reduced Graphene Oxide Composite Material
Dali Shao,1 MingpengYu,2,3 Jie Lian,2 and Shayla Sawyer1 1 Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA 2 Department of Mechanical, Aerospace & Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA 3 Department of Chemistry, Laboratory of Bio-organic Phosphorus, Tsinghua University, Beijing 100084, China. ABSTRACT An Ultraviolet (UV) photodetector with high responsivity and relative fast response speed was fabricated from three dimensional WO3 nanowires/reduced graphene oxide (3D WO3 NWs/RGO) composite materials. The 3D WO3 NDs/GN composite was synthesized using a facile three-step synthesis. First, the Na2WO4/Graphene Oxide (GO) precursor was synthesized by homogeneous precipitation. Second, the Na2WO4/GO precursor was transformed into H2WO4/GO composites by acidification. Finally, the H2WO4/GO composites were reduced to 3D WO3 NWs/RGO via hydrothermal reduction process. A maximum photoresponsivity of 4.2 A/W at 374 nm was observed under 20 V bias. The UV photodetector showed relative fast transient response, which is at least 2 orders of magnitude faster than UV photodetectors fabricated from WO3 nanowires. The good photoresponsivity and fast transient response are attributed to improved carrier transport and collection efficiency through graphene. INTRODUCTION Ultraviolet (UV) photodetectors have been investigated for various commercial and military applications, such as secure space-to-space communications, pollution monitoring, water sterilization, flame sensing and early missile plume detection [1]. To date, many different wide bandgap semiconductors such as GaN, ZnO, Si3N4, and In2O3 nanostructures have been extensively studied for UV photodetector applications [2-7]. However, only a few work reported tungsten oxide (WO3) nanomaterial for UV radiation detection [8-10]. In this work, an UV photodetector was fabricated from WO3 nanowires (NWs)/reduced graphene oxide (RGO) composite material. The WO3 NWs/RGO composite material was synthesized using a facile three-step synthesis procedure. First, the Na2WO4/GO precursor was synthesized by homogeneous precipitation. Second, the Na2WO4/GO precursor was transformed into H2WO4/GO composites by acidification. Finally, the H2WO4/GO composites were reduced to 3D WO3 NWs/RGO via hydrothermal reduction process. The UV photodetector showed fast transient response (on the order of milliseconds) and high responsivity (4.2 A/W), which are attributed to improved carrier transport and collection efficiency through graphene.
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Figure 1. Schematic illustration of the UV photodetector fabricated from the 3D WO3 NWs/RGO composite material EXPERIMENTAL DETAILS The 3D WO3 NWs were grown using an in situ hydrothermal process. In this process, 0.85 g Na2WO4ยท2H2O and 0.15 g NaCl were dissolved in deionized water and kept stirring for 6 hours. Then, 2M hydrochloric acid solution was added drop
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