title: Visible photoassisted room-temperature oxidizing gas-sensing behavior of Sn2S3semiconductor sheets through facile thermal annealing.
abstract: Well-crystallized Sn2S3semiconductor thin films with a highly (111)-crystallographic orientation were grown using RF sputtering. The surface morphology of the Sn2S3thin films exhibited a sheet-like feature. The Sn2S3crystallites with a sheet-like surface had a sharp periphery with a thickness in a nanoscale size, and the crystallite size ranged from approximately 150 to 300 nm. Postannealing the as-synthesized Sn2S3thin films further in ambient air at 400 °C engendered roughened and oxidized surfaces on the Sn2S3thin films. Transmission electron microscopy analysis revealed that the surfaces of the Sn2S3thin films transformed into a SnO2phase, and well-layered Sn2S3-SnO2heterostructure thin films were thus formed. The Sn2S3-SnO2heterostructure thin film exhibited a visible photoassisted room-temperature gas-sensing behavior toward low concentrations of NO2gases (0.2-2.5 ppm). By contrast, the pure Sn2S3thin film exhibited an unapparent room-temperature NO2gas-sensing behavior under illumination. The suitable band alignment at the interface of the Sn2S3-SnO2heterostructure thin film and rough surface features might explain the visible photoassisted room-temperature NO2gas-sensing responses of the heterostructure thin film on exposure to NO2gas at low concentrations in this work.
authors.affiliation: Institute of Materials Engineering, National Taiwan Ocean University, Keelung, 20224, Taiwan. yuanvictory@gmail.com.
authors.forename: Yuan-Chang
authors.initials: YC
authors.lastname: Liang
authors.affiliation: Institute of Materials Engineering, National Taiwan Ocean University, Keelung, 20224, Taiwan.
authors.forename: Tsai-Wen
authors.initials: TW
authors.lastname: Lung
authors.affiliation: Institute of Materials Engineering, National Taiwan Ocean University, Keelung, 20224, Taiwan.
authors.forename: Chein-Chung
authors.initials: CC
authors.lastname: Wang
keywords: Crystal feature; Gas-sensing response; Semiconductor; Sheets; Surface