  In this letter, we analyze the carrier transit delay in graphene field-effect
transistors (GFETs). GFETs are fabricated at the wafer-scale on sapphire
substrate. For a device with a gate length of 210 nm, a current gain cut-off
frequency fT of 18 GHz and 22 GHz is obtained before and after de-embedding.
The extraction of the internal (Cgs,i, Cgd,i) and external capacitances (Cgs,ex
and Cgd,ex) from the scaling behavior of the gate capacitances Cgs and Cgd
allows the intrinsic ({\tau}_int), extrinsic ({\tau}_ext) and parasitic delays
({\tau}_par) to be obtained. In addition, the extraction of the intrinsic delay
provides a new way to directly estimate carrier velocity from the experimental
data while the breakdown of the total delay into intrinsic, extrinsic, and
parasitic components can offer valuable information for optimizing RF GFETs
structures.
