Design of MoS2 NCFET Featuring Subthermodynamic Limit SS, No More Than 5 mV/V DIBR, and 0.8% Threshold Voltage Variation at 10-nm Channel Length: Modeling and Analysis

Abstract

In this work, we present a design, model, and analysis for a multilayered transition metal dichalcogenide (TMD)-based negative capacitance (NC) FET that achieves a subthreshold swing (SS) well below the thermodynamic limit, a maximum drain-induced barrier rise (DIBR) of 5 mV/V, and a threshold voltage ( ${V} _{\text {th}}$ ) roll-up confined within 0.8% at a 10-nm channel length, using hafnium zirconium oxide (Hf0.5Zr0.5O2) as the ferroelectric material. Various parameters are considered, including ferroelectric layer thickness ( ${t} _{\text {FE}}$ ), coercive electric field ( ${E} _{c}$ ), remanent polarization ( ${P} _{r}$ ), number of molybdenum disulfide (MoS2) layers (N), equivalent front and buried oxide thicknesses (EOT $_{\mathbf {f}}$ , EOTb), channel length (L), and drain-source bias ( ${V} _{\text {DS}}$ ). A surface-potential-based model, accounting for interfacial traps, is employed to compute performance parameters such as ${V}_{\text {th}}$ , SS, and DIBR. The model is validated against simulation results and existing data. The capacitance matching is performed to ensure hysteresis-free and stable NC operation. Conditions for the ferroelectric parameters ( $\alpha $ ) and ${t}_{\text {FE}}$ are derived to mitigate short-channel effects (SCEs). Optimization is carried out to achieve subthermodynamic SS while maintaining 5 mV/V DIBR and a ${V}_{\text {th}}$ roll-up below 0.8%, with values recorded for various combinations of N, EOTf, EOTb, and ${V}_{\text {DS}}$ . Unlike direct bandgap monolayer MoS2, multilayer MoS2, an indirect bandgap semiconductor, is preferred due to its lower interface-trapped charge density and augmented performance. The feasibility of the recorded $\alpha ~{t}_{\text {FE}}$ values is verified against experimental results, and an empirical model is proposed to guide the selection of ferroelectric materials for specific ${t}_{\text {FE}}$ .