Off-leakage and drive current characteristics of sub-100-nm SOI MOSFETs and impact of quantum tunnel current

This paper estimates the off-leakage current (I_off) and drive current (I_on) of various SOI MOSFETs by simulations based on the hydrodynamic-transport model; the band-to-band tunneling (BBT) effect at the drain is taken into consideration. Here, the simulations are done for SOI structures with a thick channel where the distinct quantization of energy is irrelevant to the present results. It is shown that merging hydrodynamic transport with the BBT effect is indispensable if realistic I_off estimates are to be achieved. It is shown that the symmetric double-gate SOI MOSFET does not always offer better drivability than other SOI MOSFETs, and that a single-gate SOI MOSFET with carefully selected parameters exhibits superior performance to double-gate SOI MOSFETs. It is also demonstrated that the quantum tunnel current is not significant, even in 20-nm channel SOI MOSFETs. The results suggest that we can still employ the conventional semi-classical method to estimate the off-leakage current of sub-100-nm channel low-power SOI MOSFETs.