title: Toward barrier free contact to molybdenum disulfide using graphene electrodes.
abstract: Two-dimensional layered semiconductors such as molybdenum disulfide (MoS2) have attracted tremendous interest as a new class of electronic materials. However, there are considerable challenges in making reliable contacts to these atomically thin materials. Here we present a new strategy by using graphene as the back electrodes to achieve ohmic contact to MoS2. With a finite density of states, the Fermi level of graphene can be readily tuned by a gate potential to enable a nearly perfect band alignment with MoS2. We demonstrate for the first time a transparent contact to MoS2 with zero contact barrier and linear output behavior at cryogenic temperatures (down to 1.9 K) for both monolayer and multilayer MoS2. Benefiting from the barrier-free transparent contacts, we show that a metal-insulator transition can be observed in a two-terminal MoS2 device, a phenomenon that could be easily masked by Schottky barriers found in conventional metal-contacted MoS2 devices. With further passivation by boron nitride (BN) encapsulation, we demonstrate a record-high extrinsic (two-terminal) field effect mobility up to 1300 cm(2)/(V s) in MoS2 at low temperature.
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Yuan
authors: Y
authors: Liu
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Hao
authors: H
authors: Wu
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Hung-Chieh
authors: HC
authors: Cheng
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Sen
authors: S
authors: Yang
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Enbo
authors: E
authors: Zhu
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Qiyuan
authors: Q
authors: He
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Mengning
authors: M
authors: Ding
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Dehui
authors: D
authors: Li
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Jian
authors: J
authors: Guo
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Nathan O
authors: NO
authors: Weiss
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Yu
authors: Y
authors: Huang
authors: †Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, and §California Nanosystems Institute, University of California, Los Angeles, California 90095, United States.
authors: Xiangfeng
authors: X
authors: Duan
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D004566:Electrodes; D006108:Graphite / Q000737:chemistry; D008982:Molybdenum / Q000737:chemistry*; D049329:Nanostructures; D036103:Nanotechnology; D012666:Semiconductors
chemical_list: D001896:Boron Compounds; D004220:Disulfides; C017282:boron nitride; D006108:Graphite; D008982:Molybdenum; C082964:molybdenum disulfide
keywords: MoS2; barrier free; graphene contact; high mobility; layered materials; ohmic contact