Performance comparison between p-i-n tunneling transistors and conventional MOSFETs

Field-effect transistors based on band-to-band tunneling (BTBT) have gained a lot of recent interest due to their potential for reducing power dissipation in integrated circuits. In this paper we present a detailed performance comparison between conventional n-i-n MOSFET transistors, and BTBT transistors based on the p-i-n geometry (p-i-n TFET), using semiconducting carbon nanotubes as the model channel material. Quantum transport simulations are performed using the nonequilibrium Green's function formalism including realistic phonon scattering. We find that the TFET can indeed produce subthreshold swings below the conventional MOSFET limit of 60mV/decade at room temperature leading to smaller off-currents and standby power dissipation. Phonon assisted tunneling, however, limits the off-state performance benefits that could have been achieved otherwise. Under on-state conditions the drive current and the intrinsic device delay of the TFET are mainly governed by the tunneling barrier properties. On the other hand, the switching energy for the TFET is observed to be fundamentally smaller than that for the MOSFET, reducing the dynamic power dissipation. Aforementioned reasons make the p-i-n geometry well suited for low power applications.