title: Ultraviolet photodetectors with high photosensitivity based on type-II ZnS/SnO2 core/shell heterostructured ribbons.
abstract: Semiconducting heterostructures with type-II band structure have attracted much attention due to their novel physical properties and wide applications in optoelectronics. Herein, we report, for the first time, a controlled synthesis of type-II ZnS/SnO2 heterostructured ribbon composed of SnO2 nanoparticles that uniformly cover the surface of ZnS ribbon via a simple and versatile thermal evaporation approach. Structural analysis indicated that the majority of SnO2 nanoparticles have an equivalent zone axis, i.e., <-313> of rutile SnO2, which is perpendicular to ±(2-1-10) facets (top/down surfaces) of ZnS ribbon. For those SnO2 nanoparticles decorated on ±(01-10) facets (side surfaces) of ZnS ribbon, an epitaxial relationship of (01-10)ZnO//(020)SnO2 and [2-1-10]ZnO//[001]SnO2 was identified. To explore their electronic and optoelectronic properties, we constructed field-effect transistors from as-prepared new heterostructures, which exhibited an n-type characteristic with an on/off ratio of ∼10(3) and a fast carrier mobility of ∼33.2 cm2 V(-1) s(-1). Owing to the spatial separation of photogenerated electron-hole pairs from type-II band alignment together with the good contacts between electrodes and ribbon, the resultant photodetector showed excellent photoresponse properties, including large photocurrent, high sensitivity (external quantum efficiency as high as ∼2.4×10(7)%), good stability and reproducibility, and relatively fast response speed. Our results suggest great potential of ZnS/SnO2 heterostructures for efficient UV light sensing, and, more importantly, signify the advantages of type-II semiconducting heterostructures for construction of high-performance nano-photodetectors.
authors.affiliation: Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China. mengxiangmin@mail.ipc.ac.cn.
authors.forename: Xing
authors.initials: X
authors.lastname: Huang
authors.forename: Yong-Qiang
authors.initials: YQ
authors.lastname: Yu
authors.forename: Jing
authors.initials: J
authors.lastname: Xia
authors.forename: Hua
authors.initials: H
authors.lastname: Fan
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Marc-Georg
authors.initials: MG
authors.lastname: Willinger
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Yang
authors.forename: Yang
authors.initials: Y
authors.lastname: Jiang
authors.forename: Tie-Rui
authors.initials: TR
authors.lastname: Zhang
authors.forename: Xiang-Min
authors.initials: XM
authors.lastname: Meng