bottom-up technology toshitake takahashi. background on the synthesis of graphene sheet and graphene...

Bottom-up Technology

Toshitake Takahashi

Background on the synthesis of graphene sheet and graphene nanoribbon

W. A. de Heer, et. al. Science 2006, 312, 1191.

- Peel-off method- Epitaxial growth- Chemically

AB

PmPV Suspension

in DCE solvent

C

Centrifuge

D

E

Exfoliate

Li, X. L. et al. Science 319, 1229–1232 (2008)

K. S. Novoselov, et al. Science 2004, 306, 666.

Fabrication method so far

Required new approach for Large scale application

- PMMA- MWCNT film was peeled off in KOH solution

-Top side wall of MWCNT were etched faster and removed by plasma

Making GNR from MWCNT

Diameter distribution of pristine MWCNT

Width and height distribution of GNR

Diameter/Width/Height distribution

16 nm-wide GNR devicemeasured in vacuum

-After electrical annealing-Symmetric electron and holetransport

7 nm-wide GNR devicemeasured in air

-p-type behavior due to Physisorbed O2

Electrical property of GNR

GNR fabrication with nanowire as etching mask

Electrical characteristic of GNR

-Transfer characteristic is strongly dependent on width-Opening of bandgap due to enhanced carrier confinementand edge effect as GNR width is reduced