Mobility improvement in CVD graphene by using local metal side-gate

Abstract

It has been anticipated that using a side-gate helps in the improvement of mobility over more common top-gate or back-gate graphene transistors. In this work, we presented a method of quantifying the mobility improvement. Transistors are fabricated using chemical vapour deposition graphene on SiO2/Si substrate. Characteristics of two graphene transistors with slightly different geometry are presented. The transistors are fabricated with both, a back-gate and a side-gate. Using results from experiment and technology computer-aided design simulations, field effect mobility of majority carriers (holes) is calculated by two methods. It has been observed that switching from back-gate to side-gate operation on the same transistor results in a mobility improvement of at least 1.64 times. Simulation results presented in this work exhibit a non-perpendicular direction of majority side-gate electric field induced to the two-dimensional graphene channel. This could be one of the reasons behind the mobility improvement. Because in both cases (back-gate and side-gate) the graphene channel is in contact with ambient air on top and SiO2 substrate on bottom.