Influence of metal work function on the position of the Dirac point of graphene field-effect transistors

We studied the effect of metal contact on the position of the Dirac point by means of transport measurements. To determine the sole effect of metal contact, we prepared more than 100 graphene devices following the same fabrication procedure and with a device layout that differed only in the type of metal electrode used. By measuring the peak position of the resistance, the Dirac points (Vg Dirac) were recorded in the gate response. The work function of metal-graphene complex was found to be a fair phenomenological indicator of the location of Vg Dirac in the transfer response.