title: Surface transfer doping induced effective modulation on ambipolar characteristics of few-layer black phosphorus.
abstract: Black phosphorus, a fast emerging two-dimensional material, has been configured as field effect transistors, showing a hole-transport-dominated ambipolar characteristic. Here we report an effective modulation on ambipolar characteristics of few-layer black phosphorus transistors through in situ surface functionalization with caesium carbonate (Cs2CO3) and molybdenum trioxide (MoO3), respectively. Cs2CO3 is found to strongly electron dope black phosphorus. The electron mobility of black phosphorus is significantly enhanced to ~27 cm(2) V(-1) s(-1) after 10 nm Cs2CO3 modification, indicating a greatly improved electron-transport behaviour. In contrast, MoO3 decoration demonstrates a giant hole-doping effect. In situ photoelectron spectroscopy characterization reveals significant surface charge transfer occurring at the dopants/black phosphorus interfaces. Moreover, the surface-doped black phosphorus devices exhibit a largely enhanced photodetection behaviour. Our findings coupled with the tunable nature of the surface transfer doping scheme ensure black phosphorus as a promising candidate for further complementary logic electronics.
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Du
authors.initials: D
authors.lastname: Xiang
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Cheng
authors.initials: C
authors.lastname: Han
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore [3] NanoCore, National University of Singapore, Singapore 117576, Singapore.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhong
authors.affiliation: 1] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore [2] Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Yiyang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Jiadan
authors.initials: J
authors.lastname: Lin
authors.affiliation: College of Science, National University of Defense Technology, Changsha 410073, China.
authors.forename: Xue-Ao
authors.initials: XA
authors.lastname: Zhang
authors.affiliation: 1] Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China [2] Department of Chemistry, School of Science, Tianjin University and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Ping Hu
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore [3] NanoCore, National University of Singapore, Singapore 117576, Singapore.
authors.forename: Barbaros
authors.initials: B
authors.lastname: Özyilmaz
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: A H Castro
authors.initials: AH
authors.lastname: Neto
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Andrew Thye Shen
authors.initials: AT
authors.lastname: Wee
authors.affiliation: 1] Department of Physics, National University of Singapore, Singapore 117542, Singapore [2] Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore [3] Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore [4] National University of Singapore (Suzhou) Research Institute, 377 Lin Quan Street, Suzhou Industrial Park, Jiang Su 215123, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen