A Ballistic Subthreshold Current Model for Ultra-Short Channel Recessed-Source/Drain (Re-S/D) SOI MOSFETs

摘要

This paper presents an analytical subthreshold current model for ultra-short channel recessed-source/drain (Re-S/D) SOI MOSFETs. The effects of both thermionic emission and the direct tunneling of carriers through the source-drain barrier are included in the subthreshold current modeling. The proposed model has been validated by comparing the analytical results with numerical simulation data. The developed model is used to study the subthreshold current dependency on channel thickness, recessed-source/drain thickness, channel length, and permittivity of gate dielectric. The subthreshold current is found to be increased by one order of magnitude when relative permittivity of the dielectric increases from 3.9 to 22. The subthreshold current is also found to be increased by small amount with increase in recessed source/drain thickness which may be caused by short-channel effects (SCEs). It has also been noted that the developed model predicts the subthreshold current correctly even if the channel length is less than 20 nm.