▎ 摘　　要

Carrier mobility is one of the most important parameters to evaluate the quality and uniformity of graphene. The mobility of graphene is typically extracted from the transconductance of a field-effect transistor fabricated with the graphene layer. However, the mobility value evaluated by this method is imprecise when the contact resistance is non-negligible, or the contact resistance is modulated by the gate bias, which is the case for typical graphene field-effect transistors. Here, we suggest a method for extracting the precise intrinsic field-effect mobility by considering the effective bias across the channel and its gate-induced modulation. We show that the contact resistances of typical graphene field-effect transistors are significantly modulated by gate bias and conventional methods can, therefore, cause a considerable error in the evaluation of the mobility. The proposed method in which the contact-induced error is removed gives a channel-length-independent intrinsic field-effect mobility. This method can be generally used to correctly evaluate the field-effect mobility of nano-scale or low-dimensional materials.