Oxygen-Activated Growth and Bandgap Tunability of Large Single-Crystal Bilayer Graphene

Yuanyue Liu, Yufeng Hao, Lei Wang, Cheng Tan, Junfeng Xiao, James Hone, Boris Yakobson, Hua Chen, Xiaohan Wang, Rodney Ruoff, Shu Nie, Kevin McCarty, Ji Suk, Tengfei Jiang, Tengfei Liang, Wenjing Ye, Cory Dean, Philip Kim, Luigi Colombo

Research output: Contribution to journalArticlepeer-review

279 Scopus Citations

Abstract

Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional 'surface-limited' growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 104, and a tunable bandgap up to -100 meV at a displacement field of 0.9 V nm-1.
Original languageAmerican English
Pages (from-to)426-431
Number of pages6
JournalNature Nanotechnology
Volume11
Issue number5
DOIs
StatePublished - 2016

NREL Publication Number

  • NREL/JA-5K00-65891

Keywords

  • electronic devices
  • electronic properties and devices
  • synthesis of graphene

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