title: Does p-type ohmic contact exist in WSe2-metal interfaces?
abstract: Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for the selection of favorable metal electrodes in ML/BL WSe2 devices.
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn and Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: Ruo Xi
authors.initials: RX
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn and State Key Laboratory of Information Photonics and Optical Communications & School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.
authors.forename: Ruge
authors.initials: R
authors.lastname: Quhe
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn and Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zhong
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn.
authors.forename: Linxiao
authors.initials: L
authors.lastname: Cong
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn.
authors.forename: Meng
authors.initials: M
authors.lastname: Ye
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn.
authors.forename: Zeyuan
authors.initials: Z
authors.lastname: Ni
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Song
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China.
authors.forename: Jinbo
authors.initials: J
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn.
authors.forename: Junjie
authors.initials: J
authors.lastname: Shi
authors.affiliation: Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Ju
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China. jinglu@pku.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Lu