Large-detecting-area and high-withstanding-voltage UV detectors with tunable responsivity enhancement by mediation of density of Ag nanoparticles

To detect and measure the UV arcs generated between electric power transmission facilities, high-performance large-detecting-area and high-withstanding-voltage UV detectors are badly needed in the application field of electric power transmission. Considering the performance of the detector would degenerate with increasing detecting area, we introduced Ag nanoparticles (NPs) as a plasmonic structure to create an enhancement, which benefits from realizing a large-area uniform Ag NP covering through a cost-efficient chemical method. Our detectors have a detecting area of several cm2 and the withstanding voltage can reach as high as 210 V. Based on our Ag NPs enhanced UV detectors, we carefully investigated the dependence of optical characteristics and responsivity enhancement on the density of nanoparticles. Our results show that within the density range from 0.25 to 10 mg/mL, no Ag NPs with each density could effect a responsivity augmentation, and there is a peak of enhancing factor which is 15-fold for 0.5 mg/mL. Raising the ratio of absorption and scattering to reflection, and causing a strong coupling among NPs play a key part in the enhancement. Actually, the density dependence roots in the variation of the micro-structure of Ag NPs film with density. When the density decreases, the thickness of the Ag NPs film firstly reduces accordingly until the quasi-monolayer is formed, then the area covered by NPs shrinks gradually. We realized the tunable responsivity of Ag NPs enhanced UV detectors by altering the density. This work provides a new means by density modulation, which does not attain enough attention it deserves, for mediation of plasmonic enhancement to the performance of photo-detectors.