Improved reliability of ultra-thin Hf0.5Zr0.5O2 ferroelectrics via bottom interfacial Ga incorporation through an ultrathin Ga2O3 interlayer

Hafnium oxide-based ferroelectrics such as Hf 0.5 Zr 0.5 O 2 (HZO) are promising candidates for non-volatile ferroelectric memory applications; however, reliability degradation associated with defect accumulation and interfacial defect evolution remains a major challenge, particularly in ultrathin films. In this study, we improved the reliability of metal-ferroelectric-metal capacitors based on 6 nm-thick HZO by introducing bottom-side Ga incorporation via an ultrathin Ga 2 O 3 interlayer. The optimized device, with a nominal 0.5 nm-thick Ga 2 O 3 interlayer, exhibited a remanent polarization of 2Pr = 46 μC/cm² in the wake-up-state P–E measurement and separately showed stable endurance behavior up to 10⁹ cycles under the pulse-cycling condition used in this study, whereas the reference capacitor exhibited rapid polarization degradation beginning at approximately 10⁵ cycles. Structural and electrical analyses suggest that the nominal 0.5 nm-thick Ga 2 O 3 interlayer is unlikely to remain as a fully discrete interfacial layer after processing, but instead gives rise to bottom-concentrated Ga incorporation that modifies the local defect chemistry near the lower region of HZO. In addition, Multi-V C-f measurements and angle-resolved X-ray photoelectron spectroscopy provide supporting evidence that bottom-side Ga incorporation may modify interfacial defect-related behavior in a manner consistent with mitigated evolution of internal bias and defect-assisted leakage during electrical cycling. Band alignment analysis further indicates that Ga incorporation may modify trap energetics and increase the conduction activation energy, contributing to the observed reliability improvement. These findings suggest that bottom interfacial modification via Ga incorporation can be an effective strategy toward improving the reliability of ultrathin hafnia-based ferroelectric devices.