title: Mechanical and Electrical Anisotropy of Few-Layer Black Phosphorus.
abstract: We combined reflection difference microscopy, electron transport measurements, and atomic force microscopy to characterize the mechanical and electrical anisotropy of few-layer black phosphorus. We were able to identify the lattice orientations of the two-dimensional material and construct suspended structures aligned with specific crystal axes. The approach allowed us to probe the anisotropic mechanical and electrical properties along each lattice axis in separate measurements. We measured the Young's modulus of few-layer black phosphorus to be 58.6 ± 11.7 and 27.2 ± 4.1 GPa in zigzag and armchair directions. The breaking stress scaled almost linearly with the Young's modulus and was measured to be 4.79 ± 1.43 and 2.31 ± 0.71 GPa in the two directions. We have also observed highly anisotropic transport behavior in black phosphorus and derived the conductance anisotropy to be 63.7%. The test results agreed well with theoretical predictions. Our work provided very valuable experimental data and suggested an effective characterization means for future studies on black phosphorus and anisotropic two-dimensional nanomaterials in general.
authors.forename: Jin
authors.initials: J
authors.lastname: Tao
authors.forename: Wanfu
authors.initials: W
authors.lastname: Shen
authors.forename: Sen
authors.initials: S
authors.lastname: Wu
authors.forename: Lu
authors.initials: L
authors.lastname: Liu
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Feng
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Chunguang
authors.initials: C
authors.lastname: Hu
authors.forename: Pei
authors.initials: P
authors.lastname: Yao
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Pang
authors.forename: Xuexin
authors.initials: X
authors.lastname: Duan
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Electrical Engineering, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Chongwu
authors.initials: C
authors.lastname: Zhou
authors.forename: Daihua
authors.initials: D
authors.lastname: Zhang
keywords: AFM bending; anisotropic Young’s modulus; anisotropic conductance; black phosphorus; breaking stress and strain; plasma trim; reflection difference microscopy