W18O49 Nanowire Arrays for Plasmonic Photodetector with Electromediated Broadband Photoresponse

Abstract

Plasmonic semiconductors offer significant advantages for the development of photodetectors with a tunable wide spectral response. Herein, we developed a plasmonic semiconductor photodetector based on the W18O49 nanowire array (NWA) to achieve a tunable broadband photodetector by adjusting the plasmonic absorption intensity of the W18O49 NWA. The plasmonic absorption intensity could be mediated through adjusting the free electron density of the W18O49 NWA by applying the external voltage on the W18O49 NWA-loaded electrode in HCl electrolyte. When the applied voltage decreased from +2 to −2 V, the plasmonic absorption intensity of the W18O49 NWA gradually enhanced due to the increased electron density. As a result, the responsivity and detectivity of the W18O49 NWA-based photodetector in the visible–NIR region were dramatically increased. Especially, upon 940 nm illumination, the responsivity and detectivity could reach ∼47.2 mA W–1 and ∼8.22 × 109 Jones, respectively, which is much higher than the corresponding values (∼2.9 mA W–1 and ∼4.53 × 109 Jones) obtained by the W18O49 NWA-based photodetector with a low plasmonic absorption. This work proposes a promising strategy to construct broadband-tunable photodetectors by using low-cost nonmetallic plasmonic nanostructures.