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

Xu Dong Gao,Guang Tao Fei,Shao Hui Xu,Hao Miao Ouyang,Li De Zhang,Bin Nian Zhong,Xin Hua Li

doi:10.1515/nanoph-2019-0094

Abstract

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 cmHz1/2/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.

Highlights

Plasmonic hot-electrons are highly energetic electrons that are generated in metal in the decay of surface plasmons [1]
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
The hot-electron photodetector based on a Ag/TiO2 Schottky junction may have high detectivity and a fast response speed

Summary

Introduction

Plasmonic hot-electrons are highly energetic electrons that are generated in metal in the decay of surface plasmons [1]. An Ag/TiO2 Schottky junction is considered to be an ideal material for a plasmonic hot-electron photodetector. Most of the plasmonic hotelectron photodetectors developed recently are based on Au/semiconductor-Schottky-diodes [7, 13,14,15, 17,18,19,20], Ag is considered to be a better plasmonic material than Au due to the higher density of plasmon electric fields [21] and narrower energy distribution of generated hot-electrons in Ag [1], and as a result, it can lead to a higher photoelectric conversion efficiency. The hot-electron photodetector based on a Ag/TiO2 Schottky junction may have high detectivity and a fast response speed.

Methods

Results

Conclusion