Modeling Short-Channel Effect of Elliptical Gate-All-Around MOSFET by Effective Radius

Gate-all-around (GAA) MOSFETs with elliptical cross section are studied in this letter. From the solution of the Poisson equation, an effective radius concept (
R
_eff
) is proposed to convert elliptical GAA MOSFETs into equivalent circular GAA MOSFETs for the study of short-channel effect. The
R
_eff
approach is used to estimate the subthreshold swing, drain-induced barrier lowering, and
Q
_on
/
Q
_off
ratio of elliptical GAA MOSFETs. The predictions are validated by numerical 3-D TCAD simulations, and good agreement is achieved.
R
_eff
is also simplified to an area-to-perimeter ratio of the channel under some special conditions, and its physical meaning is explained.