title: Highly Stable and Effective Doping of Graphene by Selective Atomic Layer Deposition of Ruthenium.
abstract: The sheet resistance of graphene synthesized by chemical vapor deposition is found to be significantly reduced by the selective atomic layer deposition (ALD) of Ru onto defect sites such as wrinkles and grain boundaries. With 200 ALD cycles, the sheet resistance is reduced from ∼500 to <50 Ω/sq, and the p-type carrier density is drastically increased from 1013to 1015cm-2. At the same time, the carrier mobility is reduced from ∼670 to less than 100 cm2V-1s-1. This doping of graphene proved to be very stable, with the electrical properties remaining unchanged over eight weeks of measurement. Selective deposition of Ru on defect sites also makes it possible to obtain a graphene film that is both highly transparent and electrically conductive (e.g., a sheet resistance of 125 Ω/sq with 92% optical transmittance at 550 nm). Highly doped graphene layers achieved by Ru ALD are therefore expected to provide a viable basis for transparent conducting electrodes.
authors.forename: Minsu
authors.initials: M
authors.lastname: Kim
authors.forename: Ki-Ju
authors.initials: KJ
authors.lastname: Kim
authors.affiliation: School of Materials Science and Engineering, Yeungnam University , 214-1 Dae-dong, Gyeongsan-City 38541, Korea.
authors.forename: Seung-Joon
authors.initials: SJ
authors.lastname: Lee
authors.forename: Hyun-Mi
authors.initials: HM
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Seong-Yong
authors.initials: SY
authors.lastname: Cho
authors.forename: Min-Sik
authors.initials: MS
authors.lastname: Kim
authors.affiliation: School of Materials Science and Engineering, Yeungnam University , 214-1 Dae-dong, Gyeongsan-City 38541, Korea.
authors.forename: Soo-Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Ki-Bum
authors.identifier: http://orcid.org/0000-0003-1392-5021
authors.initials: KB
authors.lastname: Kim
keywords: atomic layer deposition; graphene; graphene doping; ruthenium ALD; transparent conductive electrode