Polaron coupling in graphene field effect transistors on patterned self-assembled monolayer.
We investigated the device characteristics of a graphene field effect transistor (FET) of which interfaces were controlled by a self-assembled monolayer (SAM). Electrical transport measurements together with Raman spectroscopy characterizations for bilayer graphene (BLG) and single layer graphene (SLG) on micro-patterned SAM (mp-SAM), respectively, elucidate spatial carrier modulations on the graphene sheets driven by mp-SAM. The SLG-mp-SAM-FET device exhibits unconventional graphene p-n junction characteristics depending on the polarity of source-drain voltage. The observed characteristics can be interpreted as a velocity saturation of hole carriers coupled with polaron states, of which phonon energy is around 30 meV, on the SAM molecules at the graphene p-n junction. The SAM-based micro fabrication techniques presented in this report not only provide a spatial control of electronic properties for graphene but also lend a new perspective in the understanding of graphene-substrate interface based molecular self-assembled systems.
Department of Chemistry, Tokyo Institute of Technology, 2-12-1-W4-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan.
Kazumichi
K
Yokota
Kazuyuki
K
Takai
Yasuhiko
Y
Kudo
Yoshiaki
Y
Sato
Toshiaki
T
Enoki