W₁₈O₄₉ Nanowire Arrays for Plasmonic Photodetector with Electromediated Broadband Photoresponse

Plasmonic semiconductors offer significant advantagesfor the developmentof photodetectors with a tunable wide spectral response. Herein, wedeveloped a plasmonic semiconductor photodetector based on the W18O49 nanowire array (NWA) to achieve a tunablebroadband photodetector by adjusting the plasmonic absorption intensityof the W18O49 NWA. The plasmonic absorptionintensity could be mediated through adjusting the free electron densityof the W18O49 NWA by applying the external voltageon the W18O49 NWA-loaded electrode in HCl electrolyte.When the applied voltage decreased from +2 to -2 V, the plasmonicabsorption intensity of the W18O49 NWA graduallyenhanced due to the increased electron density. As a result, the responsivityand detectivity of the W18O49 NWA-based photodetectorin the visible-NIR region were dramatically increased. Especially,upon 940 nm illumination, the responsivity and detectivity could reach similar to 47.2 mA W-1 and similar to 8.22 x 10(9) Jones, respectively, which is much higher than the correspondingvalues (similar to 2.9 mA W-1 and similar to 4.53 x10(9) Jones) obtained by the W18O49 NWA-based photodetector with a low plasmonic absorption. This workproposes a promising strategy to construct broadband-tunable photodetectorsby using low-cost nonmetallic plasmonic nanostructures.