▎ 摘　　要

Top-gated graphene transistors operating at high frequencies (gigahertz) have been fabricated and their characteristics analyzed. The measured intrinsic current gain shows an ideal 1/f frequency dependence, indicating a FET-like behavior for graphene transistors. The cutoff frequency f(T) is found to be proportional to the do transconductance g(m) of the device, consistent with the relation f(T) = g(m)/(2 pi C(G)). The peak f(T) increases with a reduced gate length, and f(T) as high as 26 GHz is measured for a graphene transistor with a gate length of 150 nm. The work represents a significant step toward the realization of grapheme-based electronics for high-frequency applications.