title: Photoconductive properties of selenium nanowire photodetectors.
abstract: Selenium nanowires with a diameter of about 70 nm and a growth direction along [001] were fabricated via a facile solution method. Photoconductive properties of Se wires were systematically characterized via photodetectors made of single Se nanowire. The photodetectors exhibited a high light on-off current ratio (Ilight/ Idark) of 450, and a fast light response speed of millisecond rise/fall time with excellent stability and reproducibility. It was also observed that the response time strongly depend on the intensity of the illumination light: the rise time and fall time for a typical photodetector is 0.68/1.85, 0.53/1.70, 0.54/1.65, 0.51/1.59, and 0.49/1.58 ms for light intensity of 0.18, 0.26, 0.43, 0.96, and 1.89 mW/cm2, respectively, and the relationship between the light intensity and the photocurrent can be fitted by using a simple power law. The diameters of the nanowire were found to have a significant influence on the response speed with smaller Se nanowires showing higher response speed. Finally, the mechanisms of photoconduction and factors affecting the performance of the photodetectors were elucidated.
authors.affiliation: Center of Super-Diamond and Advanced Films and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, China
authors.forename: L B
authors.initials: LB
authors.lastname: Luo
authors.forename: J S
authors.initials: JS
authors.lastname: Jie
authors.forename: Z H
authors.initials: ZH
authors.lastname: Chen
authors.forename: X J
authors.initials: XJ
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Fan
authors.forename: G D
authors.initials: GD
authors.lastname: Yuan
authors.forename: Z B
authors.initials: ZB
authors.lastname: He
authors.forename: W F
authors.initials: WF
authors.lastname: Zhang
authors.forename: W J
authors.initials: WJ
authors.lastname: Zhang
authors.forename: S T
authors.initials: ST
authors.lastname: Lee