Optimization of ferroelectricity and endurance of hafnium zirconium oxide thin films by controlling element inhomogeneity

Ferroelectric thin films based on HfO_(2) have garnered increasing attention worldwide,primarily due to their remarkable compatibility with silicon and scalability,in contrast to traditional perovskite-structured ferroelectric materials.Nonetheless,significant challenges remain in their widespread commercial utilization,particularly concerning their notable wake-up effect and limited endurance.To address these challenges,we propose a novel strategy involving the inhomogeneous distribution of Hf/Zr elements within thin films and explore its effects on the ferroelectricity and endurance of Hf_(0.5)Zr_(0.5)O_(2) thin films.Through techniques such as grazing incidence X-ray diffraction,transmission electron microscopy,and piezoresponse force microscopy,we investigated the structural characteristics and domain switching behaviors of these materials.The experimental results indicate that the inhomogeneous distribution of Hf/Zr contributes to improving the frequency stability and endurance while maintaining a large remnant polarization in Hf_(0.5)Zr_(0.5)O_(2) ferroelectric thin films.By adjusting the distribution of Zr/Hf within the Hf_(0.5)Zr_(0.5)O_(2) thin films,significant enhancements in the remnant polarization(2P_(r)>35μC/cm2)and endurance(>109)along with a reduced coercive voltage can be achieved.Additionally,the fabricated ferroelectric thin films also exhibit high dielectric tunability(≥26%)under a low operating voltage of 2.5 V,whether in the wake-up state or not.This study offers a promising approach to optimize both the ferroelectricity and endurance of HfO_(2)-based thin films.

ATOMIC LAYER DEPOSITION HfO_(2)FILM USED AS BUFFER LAYER OF THE Pt/(Bi_(0.95)Nd_(0.05))(Fe_(0.95)Mn_(0.05))O_(3)/HfO_(2)/Si CAPACITORS FOR FeFET APPLICATION

Neodymium and manganese doped BiFeO_(3)-(Bi_(0.95)Nd_(0.05))(Fe_(0.95)Mn_(0.05))O_(3)(BNFMO)ferro-electric film and HfO_(2)layer with different thickness were fabricated using metal-organic decomposition and atomic layer deposition(ALD)method,respectively.Metal ferroelectric-insulator-semiconductor(MFIS)capacitors with 200 nm thick BNFMO and 5 nm thick HfO_(2)layer on silicon substrate have been prepared and characterized.It is found that there is no distinct interdifusion and reaction occurring at the interface between BNFMO/HfO_(2)and HfO_(2)/Si.The capacitance-voltage(C-V)and leakage current properties of Pt/HfO_(2)/Si capacitors with different HfO_(2)thickness were studied.The MFIS structure showed clockwise C-V hysteresis loops due to the ferroelectric polarization of BNFMO.The maximum memory window is 5 V.The.leakage current of the Pt/BNFMO/HfO_(2)/Si capacitor was about 2.1×10^(-6)A/cm^(2)at an applied voltage of 4V.