title: Modification of thermal and electronic properties of bilayer graphene by using slow Na+ions.
abstract: Bilayer graphene (BLG) has an extensive list of industrial applications in graphene-based nanodevices such as energy storage devices, flexible displays, and thermoelectric devices. By doping slow Na+ions on Li-intercalated BLG, we find significantly improved thermal and electronic properties of BLG by using angle-resolved photoemission and high-resolution core level spectroscopy (HRCLS) with synchrotron photons. Our HRCLS data reveal that the adsorbed Na+ions on a BLG produced by Li-intercalation through single layer graphene (SLG) spontaneously intercalate below the BLG, and substitute Li atoms to form Na-Si bonds at the SiC interface while preserving the same phase of BLG. This is in sharp contrast with no intercalation of Na+ions on SLG though neutral Na atoms intercalate. The Na+-induced BLG is found to be stable upon heating up to T = 400 °C, but returns to SLG when heated at Td= 500 °C. The evolution of the π-bands upon doping the Na+ions followed by thermal annealing shows that the carrier concentration of the π-band may be artificially controlled without damaging the Dirac nature of the π-electrons. The doubled desorption temperature from that (Td= 250 °C) of the Na-intercalated SLG together with the electronic stability of the Na+-intercalated BLG may find more practical and effective applications in advancing graphene-based thermoelectric devices and anode materials for rechargeable batteries.
authors: Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea.
authors: Mintae
authors: M
authors: Ryu
authors: Paengro
authors: P
authors: Lee
authors: Jingul
authors: J
authors: Kim
authors: Heemin
authors: H
authors: Park
authors: Jinwook
authors: J
authors: Chung