Porous Ag/TiO2-Schottky-diode based plasmonic hot-electron photodetector with high detectivity and fast response

Abstract

Due to the advantages of narrow energy distribution of plasmonic hot-electrons in Ag and the high density of states in the TiO₂ conduction band, an Ag/TiO₂ composite is considered to be an ideal combination to construct a plasmonic hot-electron photodetector with high detectivity and a high response speed. In this work, we fabricate a porous Ag/TiO₂-Schottky-diode based plasmonic hot-electron photodetector. This detector shows a high detectivity of 9.8 × 10¹⁰ cmHz^1/2/W and a fast response speed, with a rise and fall time of 112 μs and 24 μs, respectively, under 450 nm light illumination at zero bias voltage. In addition, the height of the Ag/TiO₂ Schottky barrier can be decreased by removing the chemisorbed oxygen from the surface of TiO₂ with ultraviolet light illumination, and as a result, the responsivity of the Ag/TiO₂ plasmonic hot-electron photodetector at 450 nm can increase from 3.4 mA/W to 7.4 mA/W.