New Pre-Requisites for Steep Sub-Threshold Tunnel Transistors

One of the major mechanisms of tunnel transistor operation is `energy filtering', which involves current switching by alignment and misalignment of energy levels in the channel of the transistor. Due to the influence of the contacts, the channel energy levels are never perfectly sharp, but have some broadening. The conventional Lorentzian lineshape leads to unacceptably slow algebraic sub-threshold current fall off. In this paper, we argue that the contacts to the tunnel transistor need to be narrowband, heavy-effective mass wires to achieve sharper-than-Lorentzian current switching.