Design and Simulation of Improved Swing and Ambipolar Effect for Tunnel FET by Band Engineering Using Metal Silicide at Drain Side

A new n-tunnel field effect transistor (TFET) structure that replaces traditional semiconductor material at drain with metal silicide was proposed to enhance device performance while simplifying process. From the TCAD simulation results, by employing metal silicide with an appropriate work function (WF) of 4.25 eV, based on simulation results, the proposed p-i-m TFET is superior to the traditional p-i-n structure by exhibiting suppressed ambipolar effect and much improved off-state current by a factor of 276 due, respectively, to reduced band-to-band tunneling and lower Shockley-Read-Hall recombination rate. In addition, enhanced on-state and off-state current ratio (ION/IOFF) by 2 orders and improved subthreshold swing with comparable on-state drive current are also achieved. More importantly, the idea of p-i-m structure is feasible from the viewpoint of process integration since metal silicide with the WF is a fab-friendly material such as TaSix and TiSix, and the variation of metal WF up to 0.1 eV is also allowed to keep the advantage of IOFF over the p-i-n TFET. The p-i-m TFET is very suitable to implement green electronics with higher performance at lower cost.