Advantages of a buried-gate structure for graphene field-effect transistor

Graphene field effect transistors (GFETs) with top-gate and back-gate structures have been extensively used without much consideration for compatibility with graphene. A comparative study of the electrical characteristics of buried-gate GFETs and top-gate GFETs revealed that the performance of buried-gate GFETs is drastically enhanced by having a better gate controllability, achieving three times higher field effect mobility (∼3000 cm² V⁻¹ s⁻¹) than top-gate GFETs with on/off ratio ∼10. Carrier scattering was also substantially improved by minimizing the fringing field effect, which is found to be the origin of high series resistance in top-gate GFETs. Moreover, we showed by electromagnetic (EM) simulation that the electric field distribution inside the transistors is more uniform at the buried-gate GFETs than the top-gate GFETs. (paper)