Band-gap engineered hot carrier tunnel transistors

Summary form only given. Inter-band tunnel field effect transistors (TFETs) with a gate controlled zener tunnel junction at the source are of interest because of its ability to operate with sub-kT/q sub-threshold slope device operation over a specified gate bias range. This allows TFETs to achieve, in principle, much higher Ion-Ioff ratio over a given gate voltage swing compared to conventional MOSFETs, making them attractive for ultra-low power operation. We present here a study on the strong non-equilibrium character of the tunnel injected carrier population in the channel of the TFETs through detailed energy balance (EB) simulations and its implication on TFET device design. We specifically show the following: (i) A large and highly inhomogeneous electric field at the source side tunnel junction at high gate voltages results in a non-equilibrium distribution of injected carriers in the TFET channel (ii) A novel source side heterojunction design enhances and sharpens the source side electric field amplitude and shape resulting in greater carrier heating and band-to-band tunneling (BTBT) currents even at moderate gate voltages (iii) The energy relaxation process o f the injected carriers on both sides of the tunnel barrier are studied as a function o f bias conditions and is a strong function of the 2-dimensional electric field profile in the TFET channel.