title: Friction and conductance imaging of sp(2)- and sp(3)-hybridized subdomains on single-layer graphene oxide.
abstract: We investigated the subdomain structures of single-layer graphene oxide (GO) by characterizing local friction and conductance using conductive atomic force microscopy. Friction and conductance mapping showed that a single-layer GO flake has subdomains several tens to a few hundreds of nanometers in lateral size. The GO subdomains exhibited low friction (high conductance) in the sp(2)-rich phase and high friction (low conductance) in the sp(3)-rich phase. Current-voltage spectroscopy revealed that the local current flow in single-layer GO depends on the quantity of hydroxyl and carboxyl groups, and epoxy bridges within the 2-dimensional carbon layer. The presence of subdomains with different sp(2)/sp(3) carbon ratios on a GO flake was also confirmed by chemical mapping using scanning transmission X-ray microscopy. These results suggest that spatial mapping of the friction and conductance can be used to rapidly identify the composition of heterogeneous single-layer GO at nanometer scale, which is essential for understanding charge transport in nanoelectronic devices.
authors.affiliation: Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Korea. jeongypark@kaist.ac.kr and Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
authors.forename: Hyunsoo
authors.initials: H
authors.lastname: Lee
authors.affiliation: School of Electrical Engineering, Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea. sungyool.choi@kaist.ac.kr.
authors.forename: Narae
authors.initials: N
authors.lastname: Son
authors.affiliation: UNIST Central Research Facilities (UCRF), UNIST, 100 Banyeon-ri, Eonyang-eup, Ulsan 44919, Korea.
authors.forename: Hu Young
authors.initials: HY
authors.lastname: Jeong
authors.affiliation: Korea University of Science and Technology (UST), 206 Gajeong-ro, Daejeon 34113, Korea.
authors.forename: Tae Gun
authors.initials: TG
authors.lastname: Kim
authors.affiliation: School of Electrical Engineering, Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea. sungyool.choi@kaist.ac.kr.
authors.forename: Gyeong Sook
authors.initials: GS
authors.lastname: Bang
authors.affiliation: School of Electrical Engineering, Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea. sungyool.choi@kaist.ac.kr.
authors.forename: Jong Yun
authors.initials: JY
authors.lastname: Kim
authors.affiliation: School of Electrical Engineering, Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea. sungyool.choi@kaist.ac.kr.
authors.forename: Gi Woong
authors.initials: GW
authors.lastname: Shim
authors.affiliation: Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Korea. jeongypark@kaist.ac.kr and Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
authors.forename: Kalyan C
authors.initials: KC
authors.lastname: Goddeti
authors.affiliation: Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Korea. jeongypark@kaist.ac.kr and Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
authors.forename: Jong Hun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Pohang Accelerator Laboratory, Pohang 37673, Korea.
authors.forename: Namdong
authors.initials: N
authors.lastname: Kim
authors.affiliation: Pohang Accelerator Laboratory, Pohang 37673, Korea.
authors.forename: Hyun-Joon
authors.initials: HJ
authors.lastname: Shin
authors.affiliation: Center for Nanometrology, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong-gu, Daejeon 34113, Korea.
authors.forename: Wondong
authors.initials: W
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Molecular-Level Interface Research Center, KAIST, 291 Daehak-ro, Daejeon 34141, Korea.
authors.forename: Sehun
authors.initials: S
authors.lastname: Kim
authors.affiliation: School of Electrical Engineering, Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea. sungyool.choi@kaist.ac.kr.
authors.forename: Sung-Yool
authors.initials: SY
authors.lastname: Choi
authors.affiliation: Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Korea. jeongypark@kaist.ac.kr and Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
authors.forename: Jeong Young
authors.initials: JY
authors.lastname: Park