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.