Recently, doped HfO2 thin films have attracted considerable attention because of promising applications in complementary metal–oxide–semiconductor (CMOS)‐compatible ferroelectric memories. Herein, the ferroelectric properties and polarization fatigue of La:HfO2 thin‐film capacitors are reported. By varying the substrate lattice constant and film thickness, a robust remanent polarization of ≈16 μC cm−2 is achieved in a 12 nm‐thick Pt/La:HfO2/La0.67Sr0.33MnO3 capacitor. Fatigue measurements are conducted using designed pulse sequences, in which the voltage, pulse width, and interval time are changed to observe the evolution of switchable polarization with increasing cycles. Severe fatigue is observed when the La:HfO2 capacitors are partially switched and the interval between the bipolar switching is elongated. These behaviors may be ascribed to the domain wall pinning scenario, in which domain switching is blocked by the migration and aggregation of charges on non‐electroneutral walls. Further analysis of the fatigue behaviors with a nucleation‐limited‐switching model shows that the mean time and activation field for polarization switching are increased in fatigued La:HfO2 capacitors because electrical stimuli are required to disperse the aggregated charges before the domains are set free. These results facilitate the design and fabrication of HfO2‐based ferroelectric memories with improved device reliability.

Role of charged defects in resistance fatigue of ferroelectric tunnel junctions has been revealed at atomic scale.

The 0.975[0.72Pb(Mg 1/3 Nb 2/3 )O 3 -0.28PbTiO 3 ]-0.025Eu 2 O 3 ceramics were prepared by a two-step sintering process including oxygen sintering and hot-pressing. An ultrahigh piezoelectric charge coefficient of 1400 pC/N and a superior optical transmittance up to 68% were simultaneously achieved. The underlying mechanism was discussed from a microstructural perspective, where the watermark domain configuration with a small domain size is responsible for the high optical transmission, while the large remanent polarization and dielectric constant and the introduced tetragonal phase with a parallel stripe domain structure are believed to synergistically contribute to the high piezoelectric coefficients. This work demonstrates that the rare-earth dopant in the PMN-PT ceramic system is conducive to enhanced transparency and piezoelectricity.

No abstract

No abstract