Non-equilibrium electron dynamics phenomena in scaled sub-100 nm gate length metal semiconductor field effect transistors: Gate-fringing, velocity overshoot, and short-channel tunneling

Ultrashort channel GaAs metal semiconductor field effect transistors were fabricated with gate lengths ranging from 30 nm to 105 nm, by electron beam lithography, in order to examine the scaling characteristics of transconductance. For gate lengths in sub-100 nanometer range, where gradual channel approximation is no longer valid, it was observed that the transconductance varies with a variety of small-dimension-related, nonequilibrium electron dynamics phenomena such as gate-fringing effect, electron velocity overshoot, and short-channel tunneling. Short-channel tunneling was suggested experimentally for the first time to explain the degradation of transistor performance, overriding an enhancement due to electron velocity overshoot for a gate length smaller than the average inelastic mean free path of an electron.