Selective Formation of Zigzag Edges in Graphene Cracks.
We report the thermally induced unconventional cracking of graphene to generate zigzag edges. This crystallography-selective cracking was observed for as-grown graphene films immediately following the cooling process subsequent to chemical vapor deposition (CVD) on Cu foil. Results from Raman spectroscopy show that the crack-derived edges have smoother zigzag edges than the chemically formed grain edges of CVD graphene. Using these cracks as nanogaps, we were also able to demonstrate the carrier tuning of graphene through the electric field effect. Statistical analysis of visual observations indicated that the crack formation results from uniaxial tension imparted by the Cu substrates together with the stress concentration at notches in the polycrystalline graphene films. On the basis of simulation results using a simplified thermal shrinkage model, we propose that the cooling-induced tension is derived from the transient lattice expansion of narrow Cu grains imparted by the thermal shrinkage of adjacent Cu grains.
Department of Chemistry, Nagoya University and Institute for Advanced Research , Nagoya 464-8602, Japan.
Miho
M
Fujihara
Department of Physics, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan.
Ryosuke
R
Inoue
Department of Physics, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan.
Rei
R
Kurita
Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan.
Toshiyuki
T
Taniuchi
Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan.
Yoshihito
Y
Motoyui
Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan.
Shik
S
Shin
Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan.
Fumio
F
Komori
Department of Physics, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan.
Yutaka
Y
Maniwa
Department of Chemistry, Nagoya University and Institute for Advanced Research , Nagoya 464-8602, Japan.
Hisanori
H
Shinohara
Department of Physics, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan.|JST-PRESTO , Kawaguchi, Saitama 332-0012, Japan.
Yasumitsu
Y
Miyata
cleavage; cracking; graphene; nanogaps; zigzag edge