Beyond Classical Transport: NEGF-Based Unveiling of Ferroelectric Charge-Plasma Vertical Nanowire Dynamics

Abstract

The theoretical 60 mV/dec subthreshold swing limit of conventional MOSFETs has motivated the exploration of alternative device architectures and materials. This work investigates the effect of embedding a ferroelectric (FE) layer in an ultrascaled vertical charge-plasma nanowire FET (VNW-FET). Unlike most previously reported FE–nanowire devices that employ channel lengths $\ge 30$ –100 nm, thicker FE layers, and are mainly targeted for memory applications, this study analyzes a 15 nm vertical nanowire with a 1.5 nm FE layer in a dopingless charge-plasma configuration. Quantum transport is modeled using mode-space nonequilibrium green’s function (NEGF) coupled with Schrödinger–Poisson equations, enabling energy-resolved analysis of transmission probability and density of states (DOSs). The influence of temperature, FE length, and FE thickness on C–V_GS and I_DS–V_GS characteristics is examined. Results show that FE integration predominantly affects the ${\mathrm {I}}_{\textit {ON}}$ , where shifts in transmission threshold and DOS redistribution enhance I_ON. Increasing FE length further improves I_ON, and the FE/SiO₂ stack enhances the I_ON/I_OFF ratio by more than an order of magnitude. The device is also evaluated for NH₃ and H₂ sensing using the Gouy–Chapman–Stern framework.