A ballistic model for subthreshold current and threshold voltage of the dual-material-gate nanosheet MOSFET

Abstract

— A ballistic model for subthreshold current of the dual-material-gate (DMG) nanosheet (NS) MOSFET is developed based on the Landauer approach, three-dimensional scaling equation, and the continuity of subthreshold current at the interface between the control gate and screen gate in the channel, The work function difference between the screen gate and control gate can be converted into the new interface-quasi-fermi-potential (IQFP) at the junction between different gate regions. Through the IQFP, the ballistic subthreshold current for DMG NS MOSFET is successfully developed. With the determined subthreshold current, the ballistic threshold voltage can also be achieved by the constant current method. Under the low and high drain voltage corresponding to their IQFPs, the subthreshold behavior is mainly governed by the contact potential and thermal voltage, respectively. Furthermore, Ohm's law regarding ballistic resistance for the DMG NS MOSFET can still be valid in the subthreshold conduction.