INVESTIGATION OF ELECTRIC AND THERMOELECTRIC PROPERTIES OF GRAPHENE NANORIBBON

In this thesis, we developed a method to fabricate ultra-narrow GNRs which is called helium ion Lithography (HIL) using helium ion microscope (HIM). Suspended GNRs with widths down to 5nm and supported GNRs with widths down to 20nm are patterned by directly modifying graphene strips through surface sputtering by helium ions. The temperature dependent conductance measurements on supported Graphene Field Effect Transistors (GFETs) show an estimated energy gap of 13mev for 60nm wide GNR. In addition, we also investigated the thermoelectric properties of GNR. GNR on Si/SiO2 substrate. Seebeck coefficient S of GNR with width of ~70nm and length of 1µm was measured as a function of the back gate voltage at different ambient temperatures. At high temperatures, the Seebeck coefficient shows a decreasing with increasing temperature which indicates an energy gap exists. The optimized value occurred at 150K, which might due to the enhanced quantum confinement effect in GNR.

Author dc:creator

• ZHANG KAIWEN

• Graphene, nanoribbon, HIM, FET, Bandgap, thermopower,