Design and analysis of novel La:HfO2 gate stacked ferroelectric tunnel FET for non-volatile memory applications

Abstract

Recent experimental studies have shown lanthanum-doped hafnium oxide (La:HfO₂) possessing ferroelectric properties. This material is of special interest since it is based on lead-free, simple binary oxide of HfO₂, and has excellent endurance property (1 × 10⁹ field cycles without fatigue. There exists substantial information about the material aspects of La:HfO₂ but it lacks proven application potential for CMOS-compatible low-power memory design. In this work, 10 % La metal cation fraction of HfO₂ (La:HfO₂) is proposed as the gate stack material in tunnel FET (TFET) for its potential as a memory device. 2D device simulations are carried out to show that the proposed ferroelectric TFET (FeTFET) provides the largest memory window (MW) as compared to present perovskite ferroelectric materials such as PZT, SBT (SrBi₂Ta₂O₉) and silicon doped (4.6 % Si in HfO₂) hafnium oxide (Si:HfO₂). The larger window is attributed to greater polarization, and the calculation of MW is quantified by the shift in threshold voltage (V_th). The simulations carried out in this work suggest that La:HfO₂ can be adopted as a potential ferroelectric material to target low-power FeTFET design at significantly reduced ferroelectric layer thickness.