A dual-gate ambipolar graphene field effect transistor

A Dual-gate graphene field effect transistor was fabricated with HfO2 and SiO2 as the back and top dielectric layers on silicon substrate, respectively. The CVD grown graphene was transferred a process by spin-coating a PMMA layer. The electrical properties of the graphene transistors were investigated. Ambipolar behavior of field effect transistor is demonstrated with the carrier mobility of the channel between 3000 to 4500cm2/Vs. It is found that the AZ5214 photoresist covered on graphene during the fabrication process induces its p-type doping and annealing can reduce the impurity concentration dramatically.