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Title: Schottky barrier contrasts in single and bi-layer graphene contacts for MoS{sub 2} field-effect transistors

We have investigated single- and bi-layer graphene as source-drain electrodes for n-type MoS{sub 2} transistors. Ti-MoS{sub 2}-graphene heterojunction transistors using both single-layer MoS{sub 2} (1M) and 4-layer MoS{sub 2} (4M) were fabricated in order to compare graphene electrodes with commonly used Ti electrodes. MoS{sub 2}-graphene Schottky barrier provided electron injection efficiency up to 130 times higher in the subthreshold regime when compared with MoS{sub 2}-Ti, which resulted in V{sub DS} polarity dependence of device parameters such as threshold voltage (V{sub TH}) and subthreshold swing (SS). Comparing single-layer graphene (SG) with bi-layer graphene (BG) in 4M devices, SG electrodes exhibited enhanced device performance with higher on/off ratio and increased field-effect mobility (μ{sub FE}) due to more sensitive Fermi level shift by gate voltage. Meanwhile, in the strongly accumulated regime, we observed opposing behavior depending on MoS{sub 2} thickness for both SG and BG contacts. Differential conductance (σ{sub d}) of 1M increases with V{sub DS} irrespective of V{sub DS} polarity, while σ{sub d} of 4M ceases monotonic growth at positive V{sub DS} values transitioning to ohmic-like contact formation. Nevertheless, the low absolute value of σ{sub d} saturation of the 4M-graphene junction demonstrates that graphene electrode could be unfavorable for high current carryingmore » transistors.« less
Authors:
; ; ; ;  [1] ; ;  [2] ; ;  [3] ;  [4] ;  [3] ;  [5]
  1. Department of Physics, Sejong University, Seoul 143-747 (Korea, Republic of)
  2. Divison of Quantum Phases and Devices, Department of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of)
  3. Center for Artificial Low-Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of)
  4. (POSTECH), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of)
  5. Samsung Electronics Company, Limited, System LSI Division, TD Team, Gyunggi 446-711 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22486205
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; EFFICIENCY; ELECTRON BEAM INJECTION; FIELD EFFECT TRANSISTORS; GRAPHENE; HETEROJUNCTIONS; LAYERS; MOLYBDENUM SULFIDES; PERFORMANCE