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Since the discovery of ferroelectricity in doped HfO2 and ZrO2 thin films over a decade ago, fluorite‐structured ferroelectric thin films have attracted much research attention due to their excellent scalability and complementary metal‐oxide semiconductor compatibility compared to conventional perovskite ferroelectric materials. Although various factors influencing the formation of the ferroelectric properties are identified, a clear understanding of the causes of the phase formation have been difficult to determine. In this work, ZrO2 films deposited by atomic layer deposition and chemical solution deposition have resulted in films with completely different structural properties. Regardless of these differences, a general relationship between strain and phase formation is established, leading to a more unified understanding of ferroelectric phase formation in undoped ZrO2 films, which can be applied to other fluorite‐structured films. [ABSTRACT FROM AUTHOR]

Inducing and detecting the polar orthorhombic phase are crucial for the establishment of ferroelectricity in HfO2‐ and ZrO2‐based thin films. Unfortunately, commonly used structural characterization techniques such as grazing incidence angle X‐ray diffraction (GIXRD) only partially allow an accurate detection of this crystalline phase, whose characteristic pattern almost coincides with the one of the tetragonal phase. As a consequence, phase determination is commonly based on peak deconvolution tracing the position of the main peak at 2θ values of around 30°, which can be assigned both to the t(101) and the o(111) plane directions and additionally be influenced by mechanical stress in the layers. Alternatively, epitaxial layers are required to differentiate the phase. Herein, using an integrated experimental–computational approach, it is shown how Raman spectroscopy can distinguish between the monoclinic, the tetragonal, and the orthorhombic phase of ZrO2. The Raman spectra calculated from first principles match the experimentally measured data and thus enable an unambiguous phase assignment. Therefore, Raman spectroscopy proves to be a powerful technique for discerning the three main crystalline phases in these materials. As demonstrated by the good agreement between structural and electrical data, it can therefore be used to predict ferroelectricity in the addressed layers. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the leakage current versus voltage characteristic of high- k thin film capacitors over a large temperature range. Fabricated samples, consisting of a 10-nm thin {\rm SrTiO}_{3} (STO) layer as a dielectric material and {\rm SrRuO}_{3}$ as electrodes, have been examined. Electrical measurements performed at different temperatures reveal leakage currents that exceed 10^{-7}~{\rm A}/{\rm cm}^{2} at 1 V, a requirement needed for dynamic random access memory (DRAM) applications. We perform a detailed simulation study for the measured samples, making use of a modified drift diffusion model, which also takes into account charge trapping/detrapping effects and nonlocal tunneling. Based on our simulations, we propose an explanation for the large leakage currents observed experimentally. They can be attributed to a trap-assisted tunneling process that is enhanced by oxygen vacancies in the STO dielectric layer. We are thus able to reproduce the temperature and voltage dependence of the measured currents and can use our model to examine the impact of different physical parameters on the behavior of the capacitor structure—a first step toward device optimization. A feasibility analysis is performed for a 1T1C DRAM cell using an optimized deep trench STO capacitor with a reduced oxygen defect density. The simulation results underline the advantages of our modeling procedure using a commercial technology computer aided design (TCAD) framework: once the complex leakage mechanism is implemented, it can be activated on arbitrary 3-D structures, taking advantage of all the postprocessing or visualization capabilities. [ABSTRACT FROM AUTHOR]

The effects of thermal annealing on Pb(Zr0.3Ti0.7)O3 ferroelectric thin film capacitors derived by chemical solution deposition with Pt electrodes were investigated. Sample-averaged structural information of the capacitors with different thermal histories was obtained from fitting the X-ray specular reflectivity using a homogeneous stratified multilayered structure model of Pt/PZT/Pt/TiOx/SiO2. Electrical measurements showed a remarkable remanent polarization reduction of up to 8.8% and an increase of the dielectric constant at low biases with increasing annealing time from 5 to 10 min. However, no evident change to the fatigue endurance was found except for the reduced initial remanent polarization. The effects of the thermal annealing on the electrical propel-ties of the ferroelectric capacitors are discussed in correlation with the structural changes in the ferroelectric thin films. [ABSTRACT FROM AUTHOR]

Since the discovery of ferroelectricity in doped HfO2 and ZrO2 thin films over a decade ago, fluorite‐structured ferroelectric thin films have attracted much research attention due to their excellent scalability and complementary metal‐oxide semiconductor compatibility compared to conventional perovskite ferroelectric materials. Although various factors influencing the formation of the ferroelectric properties are identified, a clear understanding of the causes of the phase formation have been difficult to determine. In this work, ZrO2 films deposited by atomic layer deposition and chemical solution deposition have resulted in films with completely different structural properties. Regardless of these differences, a general relationship between strain and phase formation is established, leading to a more unified understanding of ferroelectric phase formation in undoped ZrO2 films, which can be applied to other fluorite‐structured films. [ABSTRACT FROM AUTHOR]

Crystallization of Pb(Zr0.53Ti0.47)O3 (PZT) films derived from sol–gel precursor solutions using a continuous-wave (CW) 980 nm semiconductor laser is discussed in this paper. By using a 0.3 M precursor solution and repeating 4 times a sequence of drying, pyrolysis, and laser annealing (LA) processes, 150-nm-thick PZT films with (111)-preferred texture are obtained. By adjusting the laser power according to the variation in film thickness, PZT crystallization is induced throughout the film, which is confirmed by electron diffraction patterns. The dielectric constant and loss tangent measured with an oscillation voltage of 0.8 V at 10 kHz are 1200 and 0.078, respectively. The remanent polarization and coercive field of the LA-PZT film are 30 µC/cm2 and 104 kV/cm, respectively. The field-induced strain property calculated from the voltage-displacement curve obtained by an atomic force microscopy measurement is comparable to that of the PZT film fabricated by rapid thermal annealing. [ABSTRACT FROM AUTHOR]