Enhanced ferroelectric performance in Hf0.5Zr0.5O2 capacitors using ultra-thin MoS2 layer for clamping effect and oxygen vacancy suppression

• Ultra-thin (≈1 nm) MoS 2 capping layer enhanced polarization magnitude of HZO by threefold (from ≈14.8 to ≈42.2 μC cm−2). • This stems from ferroelectric o-phase stabilization through mechanical clamping enabled by strain sustainability of MoS 2 . • MoS 2 -capped HZO also demonstrated a reduction in defect concentration at the interface. • This is attributed to suppression of undesirable interfacial reactions due to dangling-bond-free nature of MoS 2 . Since the discovery of ferroelectric properties in HfO 2 -based thin films, capping effect has been extensively researched to induce ferroelectric orthorhombic phase through mechanical clamping. However, current research on capping materials has focused on oxide-based materials to address wake-up effect resulted from 3D metallic capping electrodes, yet the challenge of achieving a large double remnant polarization value remains unresolved. Here, ultra-thin (≈ 1 nm) MoS 2 , one of transition metal dichalcogenides, was employed as a novel capping layer on Hf 0.5 Zr 0.5 O 2 thin films. Notably, MoS 2 -capped Hf 0.5 Zr 0.5 O 2 films exhibited a higher orthorhombic phase fraction than uncapped films, resulting in an enhanced double remnant polarization value of ≈ 42.2 μC cm −2 . This represents approximately a three-fold increase compared to the uncapped Hf 0.5 Zr 0.5 O 2 films (≈ 14.8 μC cm −2 ), attributed to volumetric suppression via the clamping effect even with ultra-thin capping. Additionally, the MoS 2 -capped Hf 0.5 Zr 0.5 O 2 device exhibited enhanced cycling limits (>10 6 cycles), achieved by suppressed oxygen vacancies at the top electrode-Hf 0.5 Zr 0.5 O 2 film interface, thanks to the dangling bond-free nature of transition metal dichalcogenides. This study demonstrates that ultra-thin MoS 2 effectively functions as a capping layer, enhancing both remnant polarization and endurance for 1T-1C FeRAM applications while preserving the scalability of Hf 0.5 Zr 0.5 O 2 .