Towards frequency performance improvement of emerging devices without length scaling

The improvement of the intrinsic high-frequency performance of emerging transistors is commonly based on reducing electron transit time and it is pursued by either reducing the channel length or employing novel high-electron-mobility materials. For gate-all-around transistors with lateral dimensions much shorter than their length, a careful analysis of the total time-dependent current shows that a time shorter than the electron transit time along the channel controls their high-frequency behavior. Both, the standard displacement current definition and the Ramo-Shockley-Pellegrini theorem are used to demonstrate this effect. Therefore, the high-frequency performance of such transistors, with a proper geometry design, can go beyond the intrinsic limits imposed by the electron transit time.