Enhanced Ferroelectric Properties of MoS2-Capped HZO Thin Films Induced by Thermal Mismatch Stress

Abstract

Hf0.5Zr0.5O2 (HZO) is a promising material for applications to ferroelectric (FE) nanoscale devices, such as FE random access memory (FeRAM) and FE field effect transistor (FeFET), due to its down-scaling capability and CMOS compatibility. However, achieving a large memory window and low leakage current with reliable cyclic characteristics requires enhanced double remnant polarization (2Pr) value of HZO film. Here, we introduce a novel capping layer of transition metal dichalcogenides (TMDs), specifically MoS2, grown via pulsed laser deposition on atomic layer deposited HZO thin films. Notably, the monolayer MoS2-capped HZO film exhibited a higher o-phase fraction, resulting in an enhanced remanent polarization of 2Pr ≈ 35.2 μC/cm2, which represents a ≈30 % increase compared to uncapped HZO thin films (2Pr ≈ 10.2 μC/cm2). Additionally, it demonstrated longer endurance in repeated cycles than the uncapped HZO device, which may be attributed to the dangling bond-free nature of 2D TMDs. These results suggest that MoS2 could serve as an effective capping layer to overcome the trade-off between Pr and endurance in HZO-based capacitors for FeRAM applications.