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Sample records for thin film ferroelectrics

  1. Geometric shape control of thin film ferroelectrics and resulting structures

    Science.gov (United States)

    McKee, Rodney A.; Walker, Frederick J.

    2000-01-01

    A monolithic crystalline structure and a method of making involves a semiconductor substrate, such as silicon, and a ferroelectric film, such as BaTiO.sub.3, overlying the surface of the substrate wherein the atomic layers of the ferroelectric film directly overlie the surface of the substrate. By controlling the geometry of the ferroelectric thin film, either during build-up of the thin film or through appropriate treatment of the thin film adjacent the boundary thereof, the in-plane tensile strain within the ferroelectric film is relieved to the extent necessary to permit the ferroelectric film to be poled out-of-plane, thereby effecting in-plane switching of the polarization of the underlying substrate material. The method of the invention includes the steps involved in effecting a discontinuity of the mechanical restraint at the boundary of the ferroelectric film atop the semiconductor substrate by, for example, either removing material from a ferroelectric film which has already been built upon the substrate, building up a ferroelectric film upon the substrate in a mesa-shaped geometry or inducing the discontinuity at the boundary by ion beam deposition techniques.

  2. Removable polytetrafluoroethylene template based epitaxy of ferroelectric copolymer thin films

    Science.gov (United States)

    Xia, Wei; Chen, Qiusong; Zhang, Jian; Wang, Hui; Cheng, Qian; Jiang, Yulong; Zhu, Guodong

    2018-04-01

    In recent years ferroelectric polymers have shown their great potentials in organic and flexible electronics. To meet the requirements of high-performance and low energy consumption of novel electronic devices and systems, structural and electrical properties of ferroelectric polymer thin films are expected to be further optimized. One possible way is to realize epitaxial growth of ferroelectric thin films via removable high-ordered polytetrafluoroethylene (PTFE) templates. Here two key parameters in epitaxy process, annealing temperature and applied pressure, are systematically studied and thus optimized through structural and electrical measurements of ferroelectric copolymer thin films. Experimental results indicate that controlled epitaxial growth is realized via suitable combination of both parameters. Annealing temperature above the melting point of ferroelectric copolymer films is required, and simultaneously moderate pressure (around 2.0 MPa here) should be applied. Over-low pressure (around 1.0 MPa here) usually results in the failure of epitaxy process, while over-high pressure (around 3.0 MPa here) often results in residual of PTFE templates on ferroelectric thin films.

  3. Room temperature ferroelectricity in continuous croconic acid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xuanyuan; Lu, Haidong; Yin, Yuewei; Ahmadi, Zahra; Costa, Paulo S. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Zhang, Xiaozhe [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Department of Physics, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Xiao; Yu, Le; Cheng, Xuemei [Department of Physics, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010 (United States); DiChiara, Anthony D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Gruverman, Alexei, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu; Enders, Axel, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu; Xu, Xiaoshan, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States)

    2016-09-05

    Ferroelectricity at room temperature has been demonstrated in nanometer-thin quasi 2D croconic acid thin films, by the polarization hysteresis loop measurements in macroscopic capacitor geometry, along with observation and manipulation of the nanoscale domain structure by piezoresponse force microscopy. The fabrication of continuous thin films of the hydrogen-bonded croconic acid was achieved by the suppression of the thermal decomposition using low evaporation temperatures in high vacuum, combined with growth conditions far from thermal equilibrium. For nominal coverages ≥20 nm, quasi 2D and polycrystalline films, with an average grain size of 50–100 nm and 3.5 nm roughness, can be obtained. Spontaneous ferroelectric domain structures of the thin films have been observed and appear to correlate with the grain patterns. The application of this solvent-free growth protocol may be a key to the development of flexible organic ferroelectric thin films for electronic applications.

  4. Stress effects in ferroelectric perovskite thin-films

    Science.gov (United States)

    Zednik, Ricardo Johann

    The exciting class of ferroelectric materials presents the engineer with an array of unique properties that offer promise in a variety of applications; these applications include infra-red detectors ("night-vision imaging", pyroelectricity), micro-electro-mechanical-systems (MEMS, piezoelectricity), and non-volatile memory (NVM, ferroelectricity). Realizing these modern devices often requires perovskite-based ferroelectric films thinner than 100 nm. Two such technologically important material systems are (Ba,Sr)TiO3 (BST), for tunable dielectric devices employed in wireless communications, and Pb(Zr,Ti)O3 (PZT), for ferroelectric non-volatile memory (FeRAM). In general, the material behavior is strongly influenced by the mechanical boundary conditions imposed by the substrate and surrounding layers and may vary considerably from the known bulk behavior. A better mechanistic understanding of these effects is essential for harnessing the full potential of ferroelectric thin-films and further optimizing existing devices. Both materials share a common crystal structure and similar properties, but face unique challenges due to the design parameters of these different applications. Tunable devices often require very low dielectric loss as well as large dielectric tunability. Present results show that the dielectric response of BST thin-films can either resemble a dipole-relaxor or follow the accepted empirical Universal Relaxation Law (Curie-von Schweidler), depending on temperature. These behaviors in a single ferroelectric thin-film system are often thought to be mutually exclusive. In state-of-the-art high density FeRAM, the ferroelectric polarization is at least as important as the dielectric response. It was found that these properties are significantly affected by moderate biaxial tensile and compressive stresses which reversibly alter the ferroelastic domain populations of PZT at room temperature. The 90-degree domain wall motion observed by high resolution

  5. Structural, dielectric and ferroelectric characterization of PZT thin films

    Directory of Open Access Journals (Sweden)

    Araújo E.B.

    1999-01-01

    Full Text Available In this work ferroelectric thin films of PZT were prepared by the oxide precursor method, deposited on Pt/Si substrate. Films of 0.5 mm average thickness were obtained. Electrical and ferroelectric characterization were carried out in these films. The measured value of the dielectric constant for films was 455. Ferroelectricity was confirmed by Capacitance-Voltage (C-V characteristics and P-E hysteresis loops. Remanent polarization for films presented value around 5.0 µC/cm2 and a coercive field of 88.8 kV/cm.

  6. Effect of extrapolation length on the phase transformation of epitaxial ferroelectric thin films

    International Nuclear Information System (INIS)

    Hu, Z.S.; Tang, M.H.; Wang, J.B.; Zheng, X.J.; Zhou, Y.C.

    2008-01-01

    Effects of extrapolation length on the phase transformation of epitaxial ferroelectric thin films on dissimilar cubic substrates have been studied on the basis of the mean-field Landau-Ginzburg-Devonshire (LGD) thermodynamic theory by taking an uneven distribution of the interior stress with thickness into account. It was found that the polarization of epitaxial ferroelectric thin films is strongly dependent on the extrapolation length of films. The physical origin of the extrapolation length during the phase transformation from paraelectric to ferroelectric was revealed in the case of ferroelectric thin films

  7. Domain switching of fatigued ferroelectric thin films

    Science.gov (United States)

    Tak Lim, Yun; Yeog Son, Jong; Shin, Young-Han

    2014-05-01

    We investigate the domain wall speed of a ferroelectric PbZr0.48Ti0.52O3 (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue.

  8. Domain switching of fatigued ferroelectric thin films

    International Nuclear Information System (INIS)

    Tak Lim, Yun; Yeog Son, Jong; Shin, Young-Han

    2014-01-01

    We investigate the domain wall speed of a ferroelectric PbZr 0.48 Ti 0.52 O 3 (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue

  9. Functional Properties of Polydomain Ferroelectric Oxide Thin Films

    NARCIS (Netherlands)

    Houwman, Evert Pieter; Vergeer, Kurt; Koster, Gertjan; Rijnders, Augustinus J.H.M.; Nishikawa, H.; Iwata, N.; Endo, T.; Takamura, Y.; Lee, G-H.; Mele, P.

    2017-01-01

    The properties of a ferroelectric, (001)-oriented, thin film clamped to a substrate are investigated analytically and numerically. The emphasis is on the tetragonal, polydomain, ferroelectric phase, using a three domain structure, as is observed experimentally, instead of the two-domain structure

  10. Application of Dielectric, Ferroelectric and Piezoelectric Thin Film Devices in Mobile Communication and Medical Systems

    NARCIS (Netherlands)

    Klee, M.; Beelen, D.; Keurl, W.; Kiewitt, R.; Kumar, B.; Mauczok, R.; Reimann, K.; Renders, Ch.; Roest, A.; Roozeboom, F.; Steeneken, P.G.; Tiggelman, M.P.J.; Vanhelmont, F.; Wunnicke, O.; Lok, P.; Neumann, K.; Fraser, J.; Schmitz, G.

    2007-01-01

    Dielectric, ferroelectric and piezoelectric thin films are getting more and more attention for next generation mobile communication and medical systems. Thin film technologies based on dielectric, ferroelectric and piezoelectric thin films enable System-in-Package (SiP) devices, resulting in optimal

  11. Ferroelectric ultrathin perovskite films

    Science.gov (United States)

    Rappe, Andrew M; Kolpak, Alexie Michelle

    2013-12-10

    Disclosed herein are perovskite ferroelectric thin-film. Also disclosed are methods of controlling the properties of ferroelectric thin films. These films can be used in a variety materials and devices, such as catalysts and storage media, respectively.

  12. The Rayleigh law in silicon doped hafnium oxide ferroelectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Yan; Liu, Xiaohua [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian (China); Zhou, Dayu [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian (China); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China); Xu, Jin [Department of Electronic Engineering, Dalian Neusoft University of Information, Dalian (China); Cao, Fei; Dong, Xianlin [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China); Mueller, Johannes [Fraunhofer IPMS-CNT, Dresden (Germany); Schenk, Tony; Schroeder, Uwe [NaMLab gGmbH/TU Dresden (Germany)

    2015-10-15

    A wealth of studies have confirmed that the low-field hysteresis behaviour of ferroelectric bulk ceramics and thin films can be described using Rayleigh relations, and irreversible domain wall motion across the array of pining defects has been commonly accepted as the underlying micro-mechanism. Recently, HfO{sub 2} thin films incorporated with various dopants were reported to show pronounced ferroelectricity, however, their microscopic domain structure remains unclear till now. In this work, the effects of the applied electric field amplitude, frequency and temperature on the sub-coercive polarization reversal properties were investigated for 10 nm thick Si-doped HfO{sub 2} thin films. The applicability of the Rayleigh law to ultra-thin ferroelectric films was first confirmed, indicating the existence of a multi-domain structure. Since the grain size is about 20-30 nm, a direct observation of domain walls within the grains is rather challenging and this indirect method is a feasible approach to resolve the domain structure. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. The Rayleigh law in silicon doped hafnium oxide ferroelectric thin films

    International Nuclear Information System (INIS)

    Guan, Yan; Liu, Xiaohua; Zhou, Dayu; Xu, Jin; Cao, Fei; Dong, Xianlin; Mueller, Johannes; Schenk, Tony; Schroeder, Uwe

    2015-01-01

    A wealth of studies have confirmed that the low-field hysteresis behaviour of ferroelectric bulk ceramics and thin films can be described using Rayleigh relations, and irreversible domain wall motion across the array of pining defects has been commonly accepted as the underlying micro-mechanism. Recently, HfO 2 thin films incorporated with various dopants were reported to show pronounced ferroelectricity, however, their microscopic domain structure remains unclear till now. In this work, the effects of the applied electric field amplitude, frequency and temperature on the sub-coercive polarization reversal properties were investigated for 10 nm thick Si-doped HfO 2 thin films. The applicability of the Rayleigh law to ultra-thin ferroelectric films was first confirmed, indicating the existence of a multi-domain structure. Since the grain size is about 20-30 nm, a direct observation of domain walls within the grains is rather challenging and this indirect method is a feasible approach to resolve the domain structure. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Morphology-dependent photo-induced polarization recovery in ferroelectric thin films

    Science.gov (United States)

    Wang, J. Y.; Liu, G.; Sando, D.; Nagarajan, V.; Seidel, J.

    2017-08-01

    We investigate photo-induced ferroelectric domain switching in a series of Pb(Zr0.2Ti0.8)O3/La0.7Sr0.3MnO3 (PZT/LSMO) bilayer thin films with varying surface morphologies by piezoresponse force microscopy under light illumination. We demonstrate that reverse poled ferroelectric regions can be almost fully recovered under laser irradiation of the PZT layer and that the recovery process is dependent on the surface morphology on the nanometer scale. The recovery process is well described by the Kolmogorov-Avrami-Ishibashi model, and the evolution speed is controlled by light intensity, sample thickness, and initial write voltage. Our findings shed light on optical control of the domain structure in ferroelectric thin films with different surface morphologies.

  15. Electrical characterization of thin film ferroelectric capacitors

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D.; Keur, W.; Schmitz, Jurriaan; Hueting, Raymond Josephus Engelbart

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon

  16. X-ray diffraction stress analysis of ferroelectric thin films with ideal (h k l) textures considering the piezoelectric coupling effect

    International Nuclear Information System (INIS)

    Wu Huaping; Wu Linzhi; Li Jiquan; Chai Guozhong; Du Shanyi

    2010-01-01

    Ferroelectric thin films present large residual stress and strong texture during preparation, which affect the mechanical, dielectric and piezoelectric properties of the thin films. The determination of residual stresses in ferroelectric thin films with different textures is therefore very important. In this paper, an extended crystallite group model to evaluate the residual stresses of ferroelectric thin films using X-ray diffraction is proposed by considering the constitutive equation of orthogonally anisotropic ferroelectric medium. The effects of anisotropy and piezoelectric coupling on residual stresses of ferroelectric thin films are analyzed. X-ray stress factors for ideal (h k l)-textured ferroelectric thin films are obtained. An example of calculating the residual stresses of tetragonal perovskite ferroelectric thin films with (1 1 1) and (1 0 0) textures using the extended model is provided to validate the model.

  17. Enhanced electrical properties in bilayered ferroelectric thin films

    Science.gov (United States)

    Zhang, Hao; Long, WeiJie; Chen, YaQing; Guo, DongJie

    2013-03-01

    Sr2Bi4Ti5O18 (SBTi) single layered and Sr2Bi4Ti5O18/Pb(Zr0.53Ti0.47)O3 (SBTi/PZT) bilayered thin films have been prepared on Pt/TiO2/SiO2/Si substrates by pulsed-laser deposition (PLD). The related structural characterizations and electrical properties have been comparatively investigated. X-ray diffraction reveals that both films have crystallized into perovskite phases and scanning electron microscopy shows the sharp interfaces. Both films show well-saturated ferroelectric hysteresis loops, however, compared with the single layered SBTi films, the SBTi/PZT bilayered films have significantly increased remnant polarization ( P r) and decreased coercive field ( E c), with the applied field of 260 kV/cm. The measured P r and E c of SBTi and SBTi/PZT films were 7.9 μC/cm2, 88.1 kV/cm and 13.0 μC/cm2, 51.2 kV/cm, respectively. In addition, both films showed good fatigue-free characteristics, the switchable polarization decreased by 9% and 11% of the initial values after 2.2×109 switching cycles for the SBTi single layered films and the SBTi/PZT bilayered films, respectively. Our results may provide some guidelines for further optimization of multilayered ferroelectric thin films.

  18. Electrical characterisation of ferroelectric field effect transistors based on ferroelectric HfO2 thin films

    International Nuclear Information System (INIS)

    Yurchuk, Ekaterina

    2015-01-01

    Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO 2 ) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO 2 thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system. A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO 2 -based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.

  19. Impact of symmetry on the ferroelectric properties of CaTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Biegalski, Michael D.; Qiao, Liang [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Gu, Yijia; Chen, Long-Qing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16801 (United States); Mehta, Apurva [Stanford Synchrotron Lightsource SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); He, Qian; Borisevich, Albina [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Takamura, Yayoi, E-mail: ytakamura@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California Davis, Davis, California 95616 (United States)

    2015-04-20

    Epitaxial strain is a powerful tool to induce functional properties such as ferroelectricity in thin films of materials that do not possess ferroelectricity in bulk form. In this work, a ferroelectric state was stabilized in thin films of the incipient ferroelectric, CaTiO{sub 3}, through the careful control of the biaxial strain state and TiO{sub 6} octahedral rotations. Detailed structural characterization was carried out by synchrotron x-ray diffraction and scanning transmission electron microscopy. CaTiO{sub 3} films grown on La{sub 0.18}Sr{sub 0.82}Al{sub 0.59}Ta{sub 0.41}O{sub 3} (LSAT) and NdGaO{sub 3} (NGO) substrates experienced a 1.1% biaxial strain state but differed in their octahedral tilt structures. A suppression of the out-of-plane rotations of the TiO{sub 6} octahedral in films grown on LSAT substrates resulted in a robust ferroelectric I4 mm phase with remnant polarization ∼5 μC/cm{sup 2} at 10 K and T{sub c} near 140 K. In contrast, films grown on NGO substrates with significant octahedral tilting showed reduced polarization and T{sub c}. These results highlight the key role played by symmetry in controlling the ferroelectric properties of perovskite oxide thin films.

  20. Electrical characterisation of ferroelectric field effect transistors based on ferroelectric HfO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yurchuk, Ekaterina

    2015-02-06

    Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO{sub 2}) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO{sub 2} thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system. A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO{sub 2}-based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.

  1. Dynamics of space and polarization charges of ferroelectric thin films measured by atomic force microscopy

    International Nuclear Information System (INIS)

    Oh, Y.J.; Lee, J.H.; Jo, W.

    2006-01-01

    Retention behavior and local hysteresis characteristics in Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films on Pt electrodes have been investigated by electrostatic force microscopy (EFM). A sol-gel method is used to synthesize PZT thin films and drying conditions are carefully explored over a wide range of temperature. Decay and retention mechanisms of single-poled and reverse-poled regions of the ferroelectric thin films are explained by space charge redistribution. Trapping behavior of space charges is dependent on the nature of interface between ferroelectric thin films and bottom electrodes. Local measurement of polarization-electric field curves by EFM shows inhomogeneous space charge entrapment

  2. Probing-models for interdigitated electrode systems with ferroelectric thin films

    Science.gov (United States)

    Nguyen, Cuong H.; Nigon, Robin; Raeder, Trygve M.; Hanke, Ulrik; Halvorsen, Einar; Muralt, Paul

    2018-05-01

    In this paper, a new method to characterize ferroelectric thin films with interdigitated electrodes is presented. To obtain accurate properties, all parasitic contributions should be subtracted from the measurement results and accurate models for the ferroelectric film are required. Hence, we introduce a phenomenological model for the parasitic capacitance. Moreover, two common analytical models based on conformal transformations are compared and used to calculate the capacitance and the electric field. With a thin film approximation, new simplified electric field and capacitance formulas are derived. By using these formulas, more consistent CV, PV and stress-field loops for samples with different geometries are obtained. In addition, an inhomogeneous distribution of the permittivity due to the non-uniform electric field is modelled by finite element simulation in an iterative way. We observed that this inhomogeneous distribution can be treated as a homogeneous one with an effective value of the permittivity.

  3. Ferroelectric thin films using oxides as raw materials

    Directory of Open Access Journals (Sweden)

    E.B. Araújo

    1999-01-01

    Full Text Available This work describes an alternative method for the preparation of ferroelectric thin films based on pre-calcination of oxides, to be used as precursor material for a solution preparation. In order to show the viability of the proposed method, PbZr0.53Ti0.47O3 and Bi4Ti3O12 thin films were prepared on fused quartz and Si substrates. The results were analyzed by X-ray Diffraction (XRD, Scanning Electron Microscopy (SEM, Infrared Spectroscopy (IR and Rutherford Backscattering Spectroscopy (RBS. The films obtained show good quality, homogeneity and the desired stoichiometry. The estimated thickness for one layer deposition was approximately 1000 Å and 1500 Å for Bi4Ti3O12 and PbZr0.53Ti0.47O3 films, respectively.

  4. Synchrotron X-ray studies of epitaxial ferroelectric thin films and nanostructures

    Science.gov (United States)

    Klug, Jeffrey A.

    The study of ferroelectric thin films is a field of considerable scientific and technological interest. In this dissertation synchrotron x-ray techniques were applied to examine the effects of lateral confinement and epitaxial strain in ferroelectric thin films and nanostructures. Three materials systems were investigated: laterally confined epitaxial BiFeO3 nanostructures on SrTiO3 (001), ultra-thin commensurate SrTiO 3 films on Si (001), and coherently strained films of BaTiO3 on DyScO3 (110). Epitaxial films of BiFeO3 were deposited by radio frequency magnetron sputtering on SrRuO3 coated SrTiO 3 (001) substrates. Laterally confined nanostructures were fabricated using focused ion-beam processing and subsequently characterized with focused beam x-ray nanodiffraction measurements with unprecedented spatial resolution. Results from a series of rectangular nanostructures with lateral dimensions between 500 nm and 1 mum and a comparably-sized region of the unpatterned BiFeO3 film revealed qualitatively similar distributions of local strain and lattice rotation with a 2-3 times larger magnitude of variation observed in those of the nanostructures compared to the unpatterned film. This indicates that lateral confinement leads to enhanced variation in the local strain and lattice rotation fields in epitaxial BiFeO3 nanostructures. A commensurate 2 nm thick film of SrTiO3 on Si was characterized by the x-ray standing wave (XSW) technique to determine the Sr and Ti cation positions in the strained unit cell in order to verify strain-induced ferroelectricity in SrTiO3/Si. A Si (004) XSW measurement at 10°C indicated that the average Ti displacement from the midpoint between Sr planes was consistent in magnitude to that predicted by a density functional theory (DFT) calculated ferroelectric structure. The Ti displacement determined from a 35°C measurement better matched a DFT-predicted nonpolar structure. The thin film extension of the XSW technique was employed to

  5. A general analytical equation for phase diagrams of an N-layer ferroelectric thin film with two surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z X; Teng, B H; Rong, Y H; Lu, X H; Yang, X [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: phytbh@163.com

    2010-03-15

    Within the framework of effective-field theory with correlations, the phase diagrams of an N-layer ferroelectric thin film with two surface layers are studied by the differential operator technique based on the spin-1/2 transverse Ising model. A general analytical equation for the phase diagram of a ferroelectric thin film with arbitrary layer number as well as exchange interactions and transverse fields is derived, and then the effects of exchange interactions and transverse fields on phase diagrams are discussed for an arbitrary layer number N. Meanwhile, the crossover features, from the ferroelectric-dominant phase diagram (FPD) to the paraelectric-dominant phase diagram (PPD), for various parameters of an N-layer ferroelectric thin film with two surface layers are investigated. As a result, an N-independent common intersection point equation is obtained, and the three-dimensional curved surfaces for the crossover values are constructed. In comparison with the usual mean-field approximation, the differential operator technique with correlations reduces to some extent the ferroelectric features of a ferroelectric thin film.

  6. Hysteresis loop behaviors of ferroelectric thin films:A Monte Carlo simulation study

    Institute of Scientific and Technical Information of China (English)

    C. M. Bedoya-Hincapi´e; H. H. Ortiz-´Alvarez; E. Restrepo-Parra; J. J. Olaya-Fl´orez; J. E. Alfonso

    2015-01-01

    The ferroelectric response of bismuth titanate Bi4Ti3O12 (BIT) thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with three terms: the electric field applied in the z direction, the nearest dipole–dipole interaction in the transversal (x–y) direction, and the nearest dipole–dipole interaction in the direction perpendicular to the thin film (the z axis). In the sample construction, we take into consideration the dipole orientations of the monoclinic and orthorhombic structures that can appear in BIT at low temperature in the ferroelectric state. The effects of temperature, stress, and the concentration of pinned dipole defects are assessed by using the hysteresis loops. The results indicate the changes in the hysteresis area with temperature and stress, and the asymmetric hysteresis loops exhibit evidence of the imprint failure mechanism with the emergence of pinned dipolar defects. The simulated shift in the hysteresis loops conforms to the experimental ferroelectric response.

  7. Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

    Science.gov (United States)

    Ievlev, Anton V.; Chyasnavichyus, Marius; Leonard, Donovan N.; Agar, Joshua C.; Velarde, Gabriel A.; Martin, Lane W.; Kalinin, Sergei V.; Maksymovych, Petro; Ovchinnikova, Olga S.

    2018-04-01

    The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

  8. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    KAUST Repository

    Lu, Chengliang

    2013-12-02

    The mutual controls of ferroelectricity and magnetism are stepping towards practical applications proposed for quite a few promising devices in which multiferroic thin films are involved. Although ferroelectricity stemming from specific spiral spin ordering has been reported in highly distorted bulk perovskite manganites, the existence of magnetically induced ferroelectricity in the corresponding thin films remains an unresolved issue, which unfortunately halts this step. In this work, we report magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ?800% upon a field of 2 Tesla at 2 K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement, the ferroelectric coercivity corresponding to the magnetic chirality switching field is significantly increased. A picture based on coupled multicomponent magnetic structures is proposed to understand these features. Moreover, different magnetic anisotropy related to strain-suppressed GdFeO 3-type distortion and Jahn-Teller effect is identified in the films.

  9. Ferroelectric and piezoelectric thin films and their applications for integrated capacitors, piezoelectric ultrasound transducers and piezoelectric switches

    International Nuclear Information System (INIS)

    Klee, M; Boots, H; Kumar, B; Heesch, C van; Mauczok, R; Keur, W; Wild, M de; Esch, H van; Roest, A L; Reimann, K; Leuken, L van; Wunnicke, O; Zhao, J; Schmitz, G; Mienkina, M; Mleczko, M; Tiggelman, M

    2010-01-01

    Ferroelectric and piezoelectric thin films are gaining more and more importance for the integration of high performance devices in small modules. High-K 'Integrated Discretes' devices have been developed, which are based on thin film ferroelectric capacitors integrated together with resistors and ESD protection diodes in a small Si-based chip-scale package. Making use of ferroelectric thin films with relative permittivity of 950-1600 and stacking processes of capacitors, extremely high capacitance densities of 20-520 nF/mm 2 , high breakdown voltages up to 140 V and lifetimes of more than 10 years at operating voltages of 5 V and 85 deg. C are achieved. Thin film high-density capacitors play also an important role as tunable capacitors for applications such as tuneable matching circuits for RF sections of mobile phones. The performance of thin film tuneable capacitors at frequencies between 1 MHz and 1 GHz is investigated. Finally thin film piezoelectric ultrasound transducers, processed in Si- related processes, are attractive for medical imaging, since they enable large bandwidth (>100%), high frequency operation and have the potential to integrate electronics. With these piezoelectric thin film ultrasound transducers real time ultrasound images have been realized. Finally, piezoelectric thin films are used to manufacture galvanic MEMS switches. A model for the quasi-static mechanical behaviour is presented and compared with measurements.

  10. TaN interface properties and electric field cycling effects on ferroelectric Si-doped HfO2 thin films

    International Nuclear Information System (INIS)

    Lomenzo, Patrick D.; Nishida, Toshikazu; Takmeel, Qanit; Zhou, Chuanzhen; Fancher, Chris M.; Jones, Jacob L.; Lambers, Eric; Rudawski, Nicholas G.; Moghaddam, Saeed

    2015-01-01

    Ferroelectric HfO 2 -based thin films, which can exhibit ferroelectric properties down to sub-10 nm thicknesses, are a promising candidate for emerging high density memory technologies. As the ferroelectric thickness continues to shrink, the electrode-ferroelectric interface properties play an increasingly important role. We investigate the TaN interface properties on 10 nm thick Si-doped HfO 2 thin films fabricated in a TaN metal-ferroelectric-metal stack which exhibit highly asymmetric ferroelectric characteristics. To understand the asymmetric behavior of the ferroelectric characteristics of the Si-doped HfO 2 thin films, the chemical interface properties of sputtered TaN bottom and top electrodes are probed with x-ray photoelectron spectroscopy. Ta-O bonds at the bottom electrode interface and a significant presence of Hf-N bonds at both electrode interfaces are identified. It is shown that the chemical heterogeneity of the bottom and top electrode interfaces gives rise to an internal electric field, which causes the as-grown ferroelectric domains to preferentially polarize to screen positively charged oxygen vacancies aggregated at the oxidized bottom electrode interface. Electric field cycling is shown to reduce the internal electric field with a concomitant increase in remanent polarization and decrease in relative permittivity. Through an analysis of pulsed transient switching currents, back-switching is observed in Si-doped HfO 2 thin films with pinched hysteresis loops and is shown to be influenced by the internal electric field

  11. Ferroelectric BaTiO3 thin films on Ti substrate fabricated using pulsed-laser deposition.

    Science.gov (United States)

    He, J; Jiang, J C; Liu, J; Collins, G; Chen, C L; Lin, B; Giurgiutiu, V; Guo, R Y; Bhalla, A; Meletis, E I

    2010-09-01

    We report on the fabrication of ferroelectric BaTiO3 thin films on titanium substrates using pulsed laser deposition and their microstructures and properties. Electron microscopy studies reveal that BaTiO3 films are composed of crystalline assemblage of nanopillars with average cross sections from 100 nm to 200 nm. The BaTiO3 films have good interface structures and strong adhesion with respect to Ti substrates by forming a rutile TiO2 intermediate layer with a gradient microstructure. The room temperature ferroelectric polarization measurements show that the as-deposited BTO films possess nearly the same spontaneous polarization as the bulk BTO ceramics indicating formation of ferroelectric domains in the films. Successful fabrication of such ferroelectric films on Ti has significant importance for the development of new applications such as structural health monitoring spanning from aerospace to civil infrastructure. The work can be extended to integrate other ferroelectric oxide films with various promising properties to monitor the structural health of materials.

  12. Nanopolar reorientation in ferroelectric thin films

    International Nuclear Information System (INIS)

    Hubert, C.; Levy, J.; Rivkin, T. V.; Carlson, C.; Parilla, P. A.; Perkins, J. D.; Ginley, D. S.

    2001-01-01

    The influence of varying oxygen pressure P(O 2 ) during the growth of Ba 0.4 Sr 0.6 TiO 3 thin films is investigated using dielectric and local optical probes. A transition from in-plane to out-of-plane ferroelectricity is observed with increasing P(O 2 ). Signatures of in-plane and out-of-plane ferroelectricity are identified using dielectric response and time-resolved confocal scanning optical microscopy (TRCSOM). At the crossover pressure between in-plane and out-of-plane polarization (P c =85 mTorr), TRCSOM measurements reveal a soft, highly dispersive out-of-plane polarization that reorients in plane under modest applied electric fields. At higher deposition pressures, the out-of-plane polarization is hardened and is less dispersive at microwave frequencies, and the dielectric tuning is suppressed. Nanopolar reorientation is believed to be responsible for the marked increase in dielectric tuning at P(O 2 )=P c

  13. Experimental studies on the nonlinear dynamics of ferroelectric thin films and layered ferroelectricum/semiconductor structures in oscillating systems

    International Nuclear Information System (INIS)

    Barz, Kay

    2010-01-01

    In this work experimental techniques for characterization of ferroelectric nm-thin films and ferroelectric/semiconductor structures by means of nonlinear phenomena are discussed. The thin film sample is applied in a series resonant circuit. By recording time series data and amplitude-frequency-characteristics (resonance frequency shift), the nonlinear behavior can be analyzed with respect to the theoretical aspects of these effects in the framework of nonlinear dynamics. The evolving ferroelectric hysteresis is represented by the amplitude-frequency-characteristic in a very detailed form. Interpretations are presented on how transient alterations like fatigue or retention loss, affect the amplitude-frequency-characteristics. Time series analysis allows to separate the specific influence of the nonlinear components and their corresponding time constants. The work closes with suggestions for a systematic application of the presented techniques for an extended characterization of ferroelectric thin films. (orig.)

  14. Misfit strain dependence of ferroelectric and piezoelectric properties of clamped (001) epitaxial Pb(Zr0.52,Ti0.48)O3 thin films

    Science.gov (United States)

    Nguyen, Minh D.; Dekkers, Matthijn; Houwman, Evert; Steenwelle, Ruud; Wan, Xin; Roelofs, Andreas; Schmitz-Kempen, Thorsten; Rijnders, Guus

    2011-12-01

    A study on the effects of the residual strain in Pb(Zr0.52Ti0.48)O3 (PZT) thin films on the ferroelectric and piezoelectric properties is presented. Epitaxial (001)-oriented PZT thin film capacitors are sandwiched between SrRuO3 electrodes. The thin film stacks are grown on different substrate-buffer-layer combinations by pulsed laser deposition. Compressive or tensile strain caused by the difference in thermal expansion of the PZT film and substrate influences the ferroelectric and piezoelectric properties. All the PZT stacks show ferroelectric and piezoelectric behavior that is consistent with the theoretical model for strained thin films in the ferroelectric r-phase. We conclude that clamped (001) oriented Pb(Zr0.52Ti0.48)O3 thin films strained by the substrate always show rotation of the polarization vector.

  15. Dielectric response of fully and partially depleted ferroelectric thin films and inversion of the thickness effect

    International Nuclear Information System (INIS)

    Misirlioglu, I B; Yildiz, M

    2013-01-01

    We study the effect of full and partial depletion on the dielectric response characteristics of ferroelectric thin films with impurities via a computational approach. Using a thermodynamic approach along with the fundamental equations for semiconductors, we show that films with partial depletion display unique features and an enhanced dielectric response compared with those fully depleted. We find that the capacitance peak at switching can be significantly suppressed in the case of high impurity densities (>10 25 m −3 ) with relatively low ionization energy, of the order of 0.5 eV. For conserved number of species in films, electromigration of ionized impurities at room temperature is negligible and has nearly no effect on the dielectric response. In films with high impurity density, the dielectric response at zero bias is enhanced with respect to charge-free films or those with relatively low impurity density ( 24 m −3 ). We demonstrate that partially depleted films should be expected to exhibit peculiar capacitance–voltage characteristics at low and high bias and that the thickness effect probed in experiments in ferroelectric thin films could be entirely inverted in thin films with depletion charges where a higher dielectric response can be measured in thicker films. Therefore, depletion charge densities in ferroelectric thin films should be estimated before size-effect-related studies. Finally, we noted that these findings are in good qualitative agreement with dielectric measurements carried out on PbZr x Ti 1−x O 3 . (paper)

  16. Modeling the influence of the seeding layer on the transition behavior of a ferroelectric thin film

    International Nuclear Information System (INIS)

    Oubelkacem, A.; Essaoudi, I.; Ainane, A.; Saber, M.; Dujardin, F.

    2011-01-01

    The transition properties of a ferroelectric thin film with seeding layers were studied using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions. The effect of interaction parameters for the seeding layer on the phase diagram was also examined. We calculated the critical temperature and the polarization of the ferroelectric thin film for different seeding layer structures. We found that the seeding layer can greatly increase the Curie temperature and the polarization.

  17. Ferroelectric Thin-Film Capacitors and Piezoelectric Switches for Mobile Communication Applications

    NARCIS (Netherlands)

    Klee, Mareike; van Esch, Harry; Keur, Wilco; Kumar, Biju; van Leuken-Peters, Linda; Liu, Jin; Mauczok, Rüdiger; Neumann, Kai; Reimann, Klaus; Renders, Christel; Roest, Aarnoud L.; Tiggelman, M.P.J.; de Wild, Marco; Wunnicke, Olaf; Zhao, Jing

    2009-01-01

    Thin-film ferroelectric capacitors have been integrated with resistors and active functions such as ESD protection into small, miniaturized modules, which enable a board space saving of up to 80%. With the optimum materials and processes, integrated capacitors with capacitance densities of up to 100

  18. Homo-junction ferroelectric field-effect-transistor memory device using solution-processed lithium-doped zinc oxide thin films

    Science.gov (United States)

    Nayak, Pradipta K.; Caraveo-Frescas, J. A.; Bhansali, Unnat. S.; Alshareef, H. N.

    2012-06-01

    High performance homo-junction field-effect transistor memory devices were prepared using solution processed transparent lithium-doped zinc oxide thin films for both the ferroelectric and semiconducting active layers. A highest field-effect mobility of 8.7 cm2/Vs was obtained along with an Ion/Ioff ratio of 106. The ferroelectric thin film transistors showed a low sub-threshold swing value of 0.19 V/dec and a significantly reduced device operating voltage (±4 V) compared to the reported hetero-junction ferroelectric transistors, which is very promising for low-power non-volatile memory applications.

  19. Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films

    International Nuclear Information System (INIS)

    Kim, D J; Gruverman, A; Connell, J G; Seo, S S A

    2016-01-01

    Although enhanced conductivity of ferroelectric domain boundaries has been found in BiFeO 3 and Pb(Zr,Ti)O 3 films as well as hexagonal rare-earth manganite single crystals, the mechanism of the domain wall conductivity is still under debate. Using conductive atomic force microscopy, we observe enhanced conductance at the electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO 3 thin films where the structure and polarization direction are strongly constrained along the c-axis. This result indicates that domain wall conductivity in ferroelectric rare-earth manganites is not limited to charged domain walls. We show that the observed conductivity in the TbMnO 3 films is governed by a single conduction mechanism, namely, the back-to-back Schottky diodes tuned by the segregation of defects. (paper)

  20. The enhanced piezoelectricity in compositionally graded ferroelectric thin films under electric field: A role of flexoelectric effect

    Science.gov (United States)

    Qiu, Ye; Wu, Huaping; Wang, Jie; Lou, Jia; Zhang, Zheng; Liu, Aiping; Chai, Guozhong

    2018-02-01

    Compositionally graded ferroelectric thin films are found to produce large strain gradients, which can be used to tune the physical properties of materials through the flexoelectric effect, i.e., the coupling of polarization and the strain gradient. The influences of the flexoelectric effect on the polarization distribution and the piezoelectric properties in compositionally graded Ba1-xSrxTiO3 ferroelectric thin films are investigated by using an extended thermodynamic theory. The calculation results show that the presence of the flexoelectric effect tends to enhance and stabilize polarization components. The polarization rotation induced by the flexoelectric field has been predicted, which is accompanied by more uniform and orderly polarization components. A remarkable enhancement of piezoelectricity is obtained when the flexoelectric field is considered, suggesting that compositionally graded Ba1-xSrxTiO3 ferroelectric thin films with a large strain gradient are promising candidates for piezoelectric devices.

  1. Growth and properties of SrBi2TaNbO9 ferroelectric thin films using pulsed laser deposition

    International Nuclear Information System (INIS)

    Yang Pingxiong; Deng Hongmei; Shi Meirong; Tong Ziyang; Qin Sumei

    2007-01-01

    High quality SrBi 2 TaNbO 9 (SBTN) ferroelectric thin films were fabricated on platinized silicon by pulsed laser deposition. Microstructure and ferroelectric properties of the films were characterized. Optical fatigue (light/bias) for the thin films was studied and the average remanent polarization dropped by nearly 55% due to the bias/illumination treatment. Optical properties of the thin films were studied by spectroscopic ellipsometry (SE) from the ultraviolet to the infrared region. Optical constants, n ∼ 0.16 in the infrared region and n ∼ 2.12 in the visible spectral region, were determined through refractive index functions. The band gap energy is estimated to be 3.93 eV

  2. Characterisation of ferroelectric bulk materials and thin films

    CERN Document Server

    Cain, Markys G

    2014-01-01

    This book presents a comprehensive review of the most important methods used in the characterisation of piezoelectric, ferroelectric and pyroelectric materials. It covers techniques for the analysis of bulk materials and thick and thin film materials and devices. There is a growing demand by industry to adapt and integrate piezoelectric materials into ever smaller devices and structures. Such applications development requires the joint development of reliable, robust, accurate and - most importantly - relevant and applicable measurement and characterisation methods and models. In the past f

  3. Ferroelectricity, Piezoelectricity, and Dielectricity of 0.06PMnN-0.94PZT(45/55 Thin Film on Silicon Substrate

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2015-01-01

    Full Text Available The high piezoelectricity and high quality factor ferroelectric thin films are important for electromechanical applications especially the micro electromechanical system (MEMS. The ternary compound ferroelectric thin films 0.06Pb(Mn1/3, Nb2/3O3 + 0.94Pb(Zr0.45, Ti0.55O3 (0.06PMnN-0.94PZT(45/55 were deposited on silicon(100 substrates by RF magnetron sputtering method considering that Mn and Nb doping will improve PZT properties in this research. For comparison, nondoped PZT(45/55 films were also deposited. The results show that both of thin films show polycrystal structures with the main (111 and (101 orientations. The transverse piezoelectric coefficients are e31,eff=−4.03 C/m2 and e31,eff=-3.5 C/m2, respectively. These thin films exhibit classical ferroelectricity, in which the coercive electric field intensities are 2Ec=147.31 kV/cm and 2Ec=135.44 kV/cm, and the saturation polarization Ps=30.86 μC/cm2 and Ps=17.74 μC/cm2, and the remnant polarization Pr=20.44 μC/cm2 and Pr=9.87 μC/cm2, respectively. Moreover, the dielectric constants and loss are εr=681 and D=5% and εr=537 and D=4.3%, respectively. In conclusion, 0.06PMnN-0.94PZT(45/55 thin films act better than nondoped films, even though their dielectric constants are higher. Their excellent ferroelectricity, piezoelectricity, and high power and energy storage property, especially the easy fabrication, integration realizable, and potentially high quality factor, make this kind of thin films available for the realistic applications.

  4. Manipulating the ferroelectric polarization state of BaTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Datta, S.; Rioult, M.; Stanescu, D.; Magnan, H.; Barbier, A., E-mail: antoine.barbier@cea.fr

    2016-05-31

    Controlling the ferroelectric polarization at macroscopic or microscopic levels is crucial in the framework of the development of ferroelectric materials used in yet challenging photo-electrochemical (PEC) cells and spintronic applications. We report here on polarization methods allowing to electrically polarize prototypical samples of BaTiO{sub 3} (001) films. Epitaxial single crystalline layers were grown up to a thickness of 25 nm by atomic oxygen assisted molecular beam epitaxy on 1 at.% Nb doped SrTiO{sub 3} (001) single crystals. The samples were both microscopically and macroscopically polarized using Piezoresponse Force Microscopy and electrochemical poling in an electrolyte respectively. In addition we demonstrate the possibility to retrieve a quasi-native mixed ferroelectric polarization state after annealing. These polarization methods may be applied to many other ferroelectric thin films. - Highlights: • Ferroelectricity of BaTiO{sub 3} layers can be micro- and macroscopically controlled. • Microscopic ferroelectric domains are defined with piezoresponse force microscopy. • Poling in a LiClO{sub 4} electrolyte is a macroscopic poling method. • Air annealing above the Curie temperature “resets” the polarization state.

  5. Ferroelectric Thin Films Basic Properties and Device Physics for Memory Applications

    CERN Document Server

    Okuyama, Masanori

    2005-01-01

    Ferroelectric thin films continue to attract much attention due to their developing, diverse applications in memory devices, FeRAM, infrared sensors, piezoelectric sensors and actuators. This book, aimed at students, researchers and developers, gives detailed information about the basic properties of these materials and the associated device physics. All authors are acknowledged experts in the field.

  6. Flexoelectricity induced increase of critical thickness in epitaxial ferroelectric thin films

    International Nuclear Information System (INIS)

    Zhou Hao; Hong Jiawang; Zhang Yihui; Li Faxin; Pei Yongmao; Fang Daining

    2012-01-01

    Flexoelectricity describes the coupling between polarization and strain/stress gradients in insulating crystals. In this paper, using the Landau-Ginsburg-Devonshire phenomenological approach, we found that flexoelectricity could increase the theoretical critical thickness in epitaxial BaTiO 3 thin films, below which the switchable spontaneous polarization vanishes. This increase is remarkable in tensile films while trivial in compressive films due to the electrostriction caused decrease of potential barrier, which can be easily destroyed by the flexoelectricity, between the ferroelectric state and the paraelectric state in tensile films. In addition, the films are still in a uni-polar state even below the critical thickness due to the flexoelectric effect.

  7. Flexoelectricity induced increase of critical thickness in epitaxial ferroelectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Hao [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Hong Jiawang; Zhang Yihui [Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Li Faxin [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Pei Yongmao, E-mail: peiym@pku.edu.cn [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Fang Daining, E-mail: fangdn@pku.edu.cn [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China)

    2012-09-01

    Flexoelectricity describes the coupling between polarization and strain/stress gradients in insulating crystals. In this paper, using the Landau-Ginsburg-Devonshire phenomenological approach, we found that flexoelectricity could increase the theoretical critical thickness in epitaxial BaTiO{sub 3} thin films, below which the switchable spontaneous polarization vanishes. This increase is remarkable in tensile films while trivial in compressive films due to the electrostriction caused decrease of potential barrier, which can be easily destroyed by the flexoelectricity, between the ferroelectric state and the paraelectric state in tensile films. In addition, the films are still in a uni-polar state even below the critical thickness due to the flexoelectric effect.

  8. Effect of polarization fatigue on the Rayleigh coefficients of ferroelectric lead zirconate titanate thin films: Experimental evidence and implications

    Science.gov (United States)

    Lou, X. J.; Zhang, H. J.; Luo, Z. D.; Zhang, F. P.; Liu, Y.; Liu, Q. D.; Fang, A. P.; Dkhil, B.; Zhang, M.; Ren, X. B.; He, H. L.

    2014-09-01

    The effect of polarization fatigue on the Rayleigh coefficients of ferroelectric lead zirconate titanate (PZT) thin film was systematically investigated. It was found that electrical fatigue strongly affects the Rayleigh behaviour of the PZT film. Both the reversible and irreversible Rayleigh coefficients decrease with increasing the number of switching cycles. This phenomenon is attributed to the growth of an interfacial degraded layer between the electrode and the film during electrical cycling. The methodology used in this work could serve as an alternative way for evaluating the fatigue endurance and degradation in dielectric properties of ferroelectric thin-film devices during applications.

  9. Hysteresis loop behaviors of ferroelectric thin films: A Monte Carlo simulation study

    Science.gov (United States)

    M. Bedoya-Hincapié, C.; H. Ortiz-Álvarez, H.; Restrepo-Parra, E.; J. Olaya-Flórez, J.; E. Alfonso, J.

    2015-11-01

    The ferroelectric response of bismuth titanate Bi4Ti3O12 (BIT) thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with three terms: the electric field applied in the z direction, the nearest dipole-dipole interaction in the transversal (x-y) direction, and the nearest dipole-dipole interaction in the direction perpendicular to the thin film (the z axis). In the sample construction, we take into consideration the dipole orientations of the monoclinic and orthorhombic structures that can appear in BIT at low temperature in the ferroelectric state. The effects of temperature, stress, and the concentration of pinned dipole defects are assessed by using the hysteresis loops. The results indicate the changes in the hysteresis area with temperature and stress, and the asymmetric hysteresis loops exhibit evidence of the imprint failure mechanism with the emergence of pinned dipolar defects. The simulated shift in the hysteresis loops conforms to the experimental ferroelectric response. Project sponsored by the research departments of the Universidad Nacional de Colombia DIMA and DIB under Project 201010018227-“Crecimiento y caracterización eléctrica y estructural de películas delgadas de BixTiyOz producidas mediante Magnetrón Sputtering” and Project 12920-“Desarrollo teóricoexperimental de nanoestructuras basadas en Bismuto y materiales similares” and “Bisnano Project.”

  10. Origin of thermally stable ferroelectricity in a porous barium titanate thin film synthesized through block copolymer templating

    Directory of Open Access Journals (Sweden)

    Norihiro Suzuki

    2017-07-01

    Full Text Available A porous barium titanate (BaTiO3 thin film was chemically synthesized using a surfactant-assisted sol-gel method in which micelles of amphipathic diblock copolymers served as structure-directing agents. In the Raman spectrum of the porous BaTiO3 thin film, a peak corresponding to the ferroelectric tetragonal phase was observed at around 710 cm−1, and it remained stable at much higher temperature than the Curie temperature of bulk single-crystal BaTiO3 (∼130 °C. Measurements revealed that the ferroelectricity of the BaTiO3 thin film has high thermal stability. By analyzing high-resolution transmission electron microscope images of the BaTiO3 thin film by the fast Fourier transform mapping method, the spatial distribution of stress in the BaTiO3 framework was clearly visualized. Careful analysis also indicated that the porosity in the BaTiO3 thin film introduced anisotropic compressive stress, which deformed the crystals. The resulting elongated unit cell caused further displacement of the Ti4+ cation from the center of the lattice. This displacement increased the electric dipole moment of the BaTiO3 thin film, effectively enhancing its ferro(piezoelectricity.

  11. Effect of La and W dopants on dielectric and ferroelectric properties of PZT thin films prepared by sol-gel process

    International Nuclear Information System (INIS)

    Xiao, Mi; Zhang, Zebin; Zhang, Weikang; Zhang, Ping

    2018-01-01

    La or W-doped lead zirconate titanate thin films (PLZT or PZTW) were prepared on platinized silicon substrates by sol-gel process. The effects of La or W dopant on the phase development, microstructure, dielectric and ferroelectric characteristics of films were studied. For PLZT films, the optimum doping concentration was found to be 2 mol%. While for PZTW films, the dielectric and ferroelectric properties were found to be improved as the doping concentration increased. The fatigue properties of PLZT and PZTW thin films were also investigated, the results showed that A- or B-site donor doping could improve the fatigue properties of PZT thin films. The theory of oxygen vacancy was used to explain the performance improvement caused by donor doping. (orig.)

  12. Effect of La and W dopants on dielectric and ferroelectric properties of PZT thin films prepared by sol-gel process

    Science.gov (United States)

    Xiao, Mi; Zhang, Zebin; Zhang, Weikang; Zhang, Ping

    2018-01-01

    La or W-doped lead zirconate titanate thin films (PLZT or PZTW) were prepared on platinized silicon substrates by sol-gel process. The effects of La or W dopant on the phase development, microstructure, dielectric and ferroelectric characteristics of films were studied. For PLZT films, the optimum doping concentration was found to be 2 mol%. While for PZTW films, the dielectric and ferroelectric properties were found to be improved as the doping concentration increased. The fatigue properties of PLZT and PZTW thin films were also investigated, the results showed that A- or B-site donor doping could improve the fatigue properties of PZT thin films. The theory of oxygen vacancy was used to explain the performance improvement caused by donor doping.

  13. Depolarization corrections to the coercive field in thin-film ferroelectrics

    International Nuclear Information System (INIS)

    Dawber, M; Chandra, P; Littlewood, P B; Scott, J F

    2003-01-01

    Empirically, the coercive field needed to reverse the polarization in a ferroelectric increases with decreasing film thickness. For ferroelectric films of 100 μm to 100 nm in thickness the coercive field has been successfully described by a semi-empirical scaling law. Accounting for depolarization corrections, we show that this scaling behaviour is consistent with field measurements of ultrathin ferroelectric capacitors down to one nanometre in film thickness. Our results also indicate that the minimum film thickness, determined by a polarization instability, can be tuned by the choice of electrodes, and recommendations for next-generation ferroelectric devices are discussed. (letter to the editor)

  14. Depolarization corrections to the coercive field in thin-film ferroelectrics

    CERN Document Server

    Dawber, M; Littlewood, P B; Scott, J F

    2003-01-01

    Empirically, the coercive field needed to reverse the polarization in a ferroelectric increases with decreasing film thickness. For ferroelectric films of 100 mu m to 100 nm in thickness the coercive field has been successfully described by a semi-empirical scaling law. Accounting for depolarization corrections, we show that this scaling behaviour is consistent with field measurements of ultrathin ferroelectric capacitors down to one nanometre in film thickness. Our results also indicate that the minimum film thickness, determined by a polarization instability, can be tuned by the choice of electrodes, and recommendations for next-generation ferroelectric devices are discussed. (letter to the editor)

  15. Magnetoelectric properties of magnetic/ferroelectric multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung-Ok; Eum, You-Jeong; Koo, Chang-Young; Lee, Hee-Young [Yeungnam University, Gyeongsan (Korea, Republic of); Park, Jung-Min [Osaka University, Osaka (Japan); Ryu, Jung-Ho [Korea Institute of Materials Science, Changwon (Korea, Republic of)

    2014-07-15

    Magnetic/ferroelectric multilayer thin films using PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} (PZT) and two different magnetic materials, i.e., Terfenol-D and CuFe{sub 2}O{sub 4} (CuFO) layers, were fabricated, and their magnetoelectric (ME) coupling behavior was investigated. The PZT layer was first coated onto Pt/Ti/SiO{sub 2}/Si substrate by sol-gel spin coating method. Pt layer, which served as an electrode and a diffusion barrier, was grown on the PZT layer by using the ion-beam sputtering method. The ME voltage coefficients were calculated from the ME voltage data measured utilizing a magnetoelectric test system. The Terfenol-D/Pt/PZT films were found to show a higher in-plane ME voltage coefficient than that the CuFO/Pt/PZT films due primarily to the higher magnetostriction coefficient of Terfenol-D.

  16. Theoretical model for thin ferroelectric films and the multilayer structures based on them

    Energy Technology Data Exchange (ETDEWEB)

    Starkov, A. S., E-mail: starkov@iue.tuwien.ac.at; Pakhomov, O. V. [St. Petersburg National Research Univeristy ITMO, Institute of Refrigeration and Biotechnologies (Russian Federation); Starkov, I. A. [Vienna University of Technology, Institute for Microelectronics (Austria)

    2013-06-15

    A modified Weiss mean-field theory is used to study the dependence of the properties of a thin ferroelectric film on its thickness. The possibility of introducing gradient terms into the thermodynamic potential is analyzed using the calculus of variations. An integral equation is introduced to generalize the well-known Langevin equation to the case of the boundaries of a ferroelectric. An analysis of this equation leads to the existence of a transition layer at the interface between ferroelectrics or a ferroelectric and a dielectric. The permittivity of this layer is shown to depend on the electric field direction even if the ferroelectrics in contact are homogeneous. The results obtained in terms of the Weiss model are compared with the results of the models based on the correlation effect and the presence of a dielectric layer at the boundary of a ferroelectric and with experimental data.

  17. Theoretical model for thin ferroelectric films and the multilayer structures based on them

    International Nuclear Information System (INIS)

    Starkov, A. S.; Pakhomov, O. V.; Starkov, I. A.

    2013-01-01

    A modified Weiss mean-field theory is used to study the dependence of the properties of a thin ferroelectric film on its thickness. The possibility of introducing gradient terms into the thermodynamic potential is analyzed using the calculus of variations. An integral equation is introduced to generalize the well-known Langevin equation to the case of the boundaries of a ferroelectric. An analysis of this equation leads to the existence of a transition layer at the interface between ferroelectrics or a ferroelectric and a dielectric. The permittivity of this layer is shown to depend on the electric field direction even if the ferroelectrics in contact are homogeneous. The results obtained in terms of the Weiss model are compared with the results of the models based on the correlation effect and the presence of a dielectric layer at the boundary of a ferroelectric and with experimental data

  18. Theoretical model for thin ferroelectric films and the multilayer structures based on them

    Science.gov (United States)

    Starkov, A. S.; Pakhomov, O. V.; Starkov, I. A.

    2013-06-01

    A modified Weiss mean-field theory is used to study the dependence of the properties of a thin ferroelectric film on its thickness. The possibility of introducing gradient terms into the thermodynamic potential is analyzed using the calculus of variations. An integral equation is introduced to generalize the well-known Langevin equation to the case of the boundaries of a ferroelectric. An analysis of this equation leads to the existence of a transition layer at the interface between ferroelectrics or a ferroelectric and a dielectric. The permittivity of this layer is shown to depend on the electric field direction even if the ferroelectrics in contact are homogeneous. The results obtained in terms of the Weiss model are compared with the results of the models based on the correlation effect and the presence of a dielectric layer at the boundary of a ferroelectric and with experimental data.

  19. Effects of surface modification on the critical behaviour in multiple-surface-layer ferroelectric thin films

    International Nuclear Information System (INIS)

    Lu, Z X

    2013-01-01

    Using the usual mean-field theory approximation, the critical behaviour (i.e. the Curie temperature T c and the critical surface transverse field Ω sc ) in a multiple-surface-layer ferroelectric thin film is studied on the basis of the spin- 1/2 transverse Ising model. The dependence of the Curie temperature T c on the surface transverse field Ω s and the surface layer number N s are discussed in detail. Meanwhile the dependence of the critical surface transverse field Ω sc on the surface layer number N s is also examined. The numerical results indicate that the critical behaviour of ferroelectric thin films is obviously affected by modifications of the surface transverse field Ω s and surface layer number N s .

  20. The effect of K and Na excess on the ferroelectric and piezoelectric properties of K0.5Na0.5NbO3 thin films

    Science.gov (United States)

    Ahn, C. W.; Y Lee, S.; Lee, H. J.; Ullah, A.; Bae, J. S.; Jeong, E. D.; Choi, J. S.; Park, B. H.; Kim, I. W.

    2009-11-01

    We have fabricated K0.5Na0.5NbO3 (KNN) thin films on Pt substrates by a chemical solution deposition method and investigated the effect of K and Na excess (0-30 mol%) on ferroelectric and piezoelectric properties of KNN thin film. It was found that with increasing K and Na excess in a precursor solution from 0 to 30 mol%, the leakage current and ferroelectric properties were strongly affected. KNN thin film synthesized by using 20 mol% K and Na excess precursor solution exhibited a low leakage current density and well saturated ferroelectric P-E hysteresis loops. Moreover, the optimized KNN thin film had good fatigue resistance and a piezoelectric constant of 40 pm V-1, which is comparable to that of polycrystalline PZT thin films.

  1. The effect of K and Na excess on the ferroelectric and piezoelectric properties of K0.5Na0.5NbO3 thin films

    International Nuclear Information System (INIS)

    Ahn, C W; Bae, J S; Jeong, E D; Lee, S Y; Lee, H J; Ullah, A; Kim, I W; Choi, J S; Park, B H

    2009-01-01

    We have fabricated K 0.5 Na 0.5 NbO 3 (KNN) thin films on Pt substrates by a chemical solution deposition method and investigated the effect of K and Na excess (0-30 mol%) on ferroelectric and piezoelectric properties of KNN thin film. It was found that with increasing K and Na excess in a precursor solution from 0 to 30 mol%, the leakage current and ferroelectric properties were strongly affected. KNN thin film synthesized by using 20 mol% K and Na excess precursor solution exhibited a low leakage current density and well saturated ferroelectric P-E hysteresis loops. Moreover, the optimized KNN thin film had good fatigue resistance and a piezoelectric constant of 40 pm V -1 , which is comparable to that of polycrystalline PZT thin films.

  2. Total-dose radiation-induced degradation of thin film ferroelectric capacitors

    International Nuclear Information System (INIS)

    Schwank, J.R.; Nasby, R.D.; Miller, S.L.; Rodgers, M.S.; Dressendorfer, P.V.

    1990-01-01

    Thin film PbZr y Ti 1-y O 3 (PZT) ferroelectric memories offer the potential for radiation-hardened, high-speed nonvolatile memories with good retention and fatigue properties. In this paper we explore in detail the radiation hardness of PZT ferroelectric capacitors. Ferroelectric capacitors were irradiated using x-ray and Co-60 sources to dose levels up to 16 Mrad(Si). The capacitors were characterized for their memory properties both before and after irradiation. The radiation hardness was process dependent. Three out of four processes resulted in capacitors that showed less than 30% radiation-induced degradation in retained polarization charge and remanent polarization after irradiating to 16 Mrad(Si). On the other hand, one of the processes showed significant radiation-induced degradation in retained polarization charge and remanent polarization at dose levels above 1 Mrad(Si). The decrease in retained polarization charge appears to be due to an alteration of the switching characteristics of the ferroelectric due to changes in the internal fields. The radiation-induced degradation is recoverable by a postirradiation biased anneal and can be prevented entirely if devices are cycled during irradiation. The authors have developed a model to simulate the observed degradation

  3. Nano-embossing technology on ferroelectric thin film Pb(Zr0.3,Ti0.7O3 for multi-bit storage application

    Directory of Open Access Journals (Sweden)

    Lu Qian

    2011-01-01

    Full Text Available Abstract In this work, we apply nano-embossing technique to form a stagger structure in ferroelectric lead zirconate titanate [Pb(Zr0.3, Ti0.7O3 (PZT] films and investigate the ferroelectric and electrical characterizations of the embossed and un-embossed regions, respectively, of the same films by using piezoresponse force microscopy (PFM and Radiant Technologies Precision Material Analyzer. Attributed to the different layer thickness of the patterned ferroelectric thin film, two distinctive coercive voltages have been obtained, thereby, allowing for a single ferroelectric memory cell to contain more than one bit of data.

  4. Preparation of Ferroelectric Thin Films of Bismuth Layer Structured Compounds

    Science.gov (United States)

    Watanabe, Hitoshi; Mihara, Takashi; Yoshimori, Hiroyuki; Araujo, Carlos

    1995-09-01

    Ferroelectric thin films of bismuth layer structured compounds, SrBi2Ta2O9, SrBi2Nb2O9, SrBi4Ti4O15 and their solid solutions, were formed onto a sputtered platinum layer on a silicon substrate using spin-on technique and metal-organic decomposition (MOD) method. X-ray diffraction (XRD) analysis and some electrical measurements were performed on the prepared thin films. XRD results of SrBi2(Ta1- x, Nb x)2O9 films (0≤x≤1) showed that niobium ions substitute for tantalum ions in an arbitrary ratio without any change of the layer structure and lattice constants. Furthermore, XRD results of SrBi2 xTa2O9 films (0≤x≤1.5) indicated that the formation of the bismuth layer structure does not always require an accurate bismuth content. The layer structure was formed above 50% of the stoichiometric bismuth content in the general formula. SrBi2(Ta1- x, Nb x)2O9 films with various Ta/Nb ratios have large enough remanent polarization for nonvolatile memory application and have shown high fatigue resistance against 1011 cycles of full switching of the remanent polarization. Mixture films of the three compounds were also investigated.

  5. THIN FILMS OF A NEW ORGANIC SINGLE-COMPONENT FERROELECTRIC 2-METHYLBENZIMIDAZOLE

    Directory of Open Access Journals (Sweden)

    E. V. Balashova

    2016-09-01

    Full Text Available Subject of Research.We present results of structural and dielectric study of organic ferroelectric 2-methylbenzimidazole (MBI thin films. Method. The films have been grown on substrates of leuco-sapphire, fused and crystalline silica, neodymium gallate, bismuth germanate, gold, aluminium, platinum. The films have been grown by two different methods: substrate covering by ethanol solution of MBI and subsequent ethanol evaporation; sublimation at the temperature near 375 K under atmospheric pressure. Crystallographic orientation studies have been performed by means of «DRON-3» X-ray diffractometer, block structure of the films has been determined by «LaboPol-3» polarizing microscope. Small-signal dielectric response has been received with the use of «MIT 9216A» digital LCR-meter, while strong-signal dielectric response has been studied by Sawyer-Tower circuit. Main Resuts. We have shown that the films obtained by evaporation are continuous and textured. Obtained film structure depends on the concentration of the solution. Films may consist of blocks that are splitted crystals like spherulite. Spontaneous polarization components in such films may be directed both perpendicularly and in the film plane. We have also obtained structures consisting of single-crystal blocks with spontaneous polarization components being allocated in the film plane. Block sizes vary from a few to hundreds of microns. Films obtained by sublimation are amorphous or dendritic. The dielectric properties of the films obtained by evaporation have been studied. We have shown that the dielectric constant and dielectric loss tangent increase under heating. The dielectric hysteresis loops are observed at the temperature equal to 291-379 K. The remnant polarization increases with temperature for constant amplitude of the external electric field, and achieves 4.5mC/cm2, while the coercive field remains constant. We propose that such behavior is explained by increase of the

  6. Wake-up effects in Si-doped hafnium oxide ferroelectric thin films

    International Nuclear Information System (INIS)

    Zhou, Dayu; Xu, Jin; Li, Qing; Guan, Yan; Cao, Fei; Dong, Xianlin; Müller, Johannes; Schenk, Tony; Schröder, Uwe

    2013-01-01

    Hafnium oxide based ferroelectric thin films have shown potential as a promising alternative material for non-volatile memory applications. This work reports the switching stability of a Si-doped HfO 2 film under bipolar pulsed-field operation. High field cycling causes a “wake-up” in virgin “pinched” polarization hysteresis loops, demonstrated by an enhancement in remanent polarization and a shift of negative coercive voltage. The rate of wake-up is accelerated by either reducing the frequency or increasing the amplitude of the cycling field. We suggest de-pinning of domains due to reduction of the defect concentration at bottom electrode interface as origin of the wake-up

  7. Far infrared and terahertz spectroscopy of ferroelectric soft modes in thin films: a review

    Czech Academy of Sciences Publication Activity Database

    Petzelt, Jan; Kamba, Stanislav

    2016-01-01

    Roč. 503, č. 1 (2016), s. 19-44 ISSN 0015-0193 R&D Projects: GA ČR GA15-08389S Institutional support: RVO:68378271 Keywords : soft mode * central mode * ferroelectric thin film * terahertz spectroscopy * far-infrared spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.551, year: 2016

  8. Aggregate linear properties of ferroelectric ceramics and polycrystalline thin films: Calculation by the method of effective piezoelectric medium

    Science.gov (United States)

    Pertsev, N. A.; Zembilgotov, A. G.; Waser, R.

    1998-08-01

    The effective dielectric, piezoelectric, and elastic constants of polycrystalline ferroelectric materials are calculated from single-crystal data by an advanced method of effective medium, which takes into account the piezoelectric interactions between grains in full measure. For bulk BaTiO3 and PbTiO3 polarized ceramics, the dependences of material constants on the remanent polarization are reported. Dielectric and elastic constants are computed also for unpolarized c- and a-textured ferroelectric thin films deposited on cubic or amorphous substrates. It is found that the dielectric properties of BaTiO3 and PbTiO3 polycrystalline thin films strongly depend on the type of crystal texture. The influence of two-dimensional clamping by the substrate on the dielectric and piezoelectric responses of polarized films is described quantitatively and shown to be especially important for the piezoelectric charge coefficient of BaTiO3 films.

  9. Homo-junction ferroelectric field-effect-transistor memory device using solution-processed lithium-doped zinc oxide thin films

    KAUST Repository

    Nayak, Pradipta K.; Caraveo-Frescas, J. A.; Bhansali, Unnat. S.; Alshareef, Husam N.

    2012-01-01

    High performance homo-junction field-effect transistor memory devices were prepared using solution processed transparent lithium-doped zinc oxide thin films for both the ferroelectric and semiconducting active layers. A highest field-effect mobility

  10. Visualization of dielectric constant-electric field-temperature phase maps for imprinted relaxor ferroelectric thin films

    International Nuclear Information System (INIS)

    Frederick, J. C.; Kim, T. H.; Maeng, W.; Brewer, A. A.; Podkaminer, J. P.; Saenrang, W.; Vaithyanathan, V.; Schlom, D. G.; Li, F.; Chen, L.-Q.; Trolier-McKinstry, S.; Rzchowski, M. S.; Eom, C. B.

    2016-01-01

    The dielectric phase transition behavior of imprinted lead magnesium niobate–lead titanate relaxor ferroelectric thin films was mapped as a function of temperature and dc bias. To compensate for the presence of internal fields, an external electric bias was applied while measuring dielectric responses. The constructed three-dimensional dielectric maps provide insight into the dielectric behaviors of relaxor ferroelectric films as well as the temperature stability of the imprint. The transition temperature and diffuseness of the dielectric response correlate with crystallographic disorder resulting from strain and defects in the films grown on strontium titanate and silicon substrates; the latter was shown to induce a greater degree of disorder in the film as well as a dielectric response lower in magnitude and more diffuse in nature over the same temperature region. Strong and stable imprint was exhibited in both films and can be utilized to enhance the operational stability of piezoelectric devices through domain self-poling.

  11. Effects of Mn doping on the ferroelectric properties of PZT thin films

    International Nuclear Information System (INIS)

    Zhang Qi

    2004-01-01

    The effects of Mn doping on the ferroelectric properties of Pb(Zr 0.3 Ti 0.7 )O 3 (PZT) thin films on Pt/Ti/SiO 2 /Si substrates have been investigated. The composition of the PZT and Mn doping level are Pb(Zr 0.3 Ti 0.7 ) 1-x Mn x O 3 (x = 0,0.2,0.5,1,2,4 mol%). The PZT thin films doped with a small amount of Mn 2+ (x ≤ 1) showed almost no hysteretic fatigue up to 10 10 switching bipolar pulse cycles, coupled with excellent retention properties. However, excessive additions of manganese made the fatigue behaviour worse. We propose that the addition of small amounts of Mn is able to reduce the oxygen vacancy concentration due to the combination of Mn 2+ and oxygen vacancies in PZT films, forming Mn 4+ ions. The interfacial layer between the Pt electrode and PZT films and Mn-doped PZT (x = 4) was detected by measuring the dielectric constant of thin films of different thickness. However, this interfacial layer was not detected in Mn-doped PZT (x = 1). These observations support the concept of the preferential electromigration of oxygen vacancies into sites in planes parallel to the electrodes, which is probably responsible for the hysteretic fatigue

  12. Homo-junction ferroelectric field-effect-transistor memory device using solution-processed lithium-doped zinc oxide thin films

    KAUST Repository

    Nayak, Pradipta K.

    2012-06-22

    High performance homo-junction field-effect transistor memory devices were prepared using solution processed transparent lithium-doped zinc oxide thin films for both the ferroelectric and semiconducting active layers. A highest field-effect mobility of 8.7 cm2/Vs was obtained along with an Ion/Ioff ratio of 106. The ferroelectric thin filmtransistors showed a low sub-threshold swing value of 0.19 V/dec and a significantly reduced device operating voltage (±4 V) compared to the reported hetero-junction ferroelectrictransistors, which is very promising for low-power non-volatile memory applications.

  13. Imaging Local Polarization in Ferroelectric Thin Films by Coherent X-Ray Bragg Projection Ptychography

    Science.gov (United States)

    Hruszkewycz, S. O.; Highland, M. J.; Holt, M. V.; Kim, Dongjin; Folkman, C. M.; Thompson, Carol; Tripathi, A.; Stephenson, G. B.; Hong, Seungbum; Fuoss, P. H.

    2013-04-01

    We used x-ray Bragg projection ptychography (BPP) to map spatial variations of ferroelectric polarization in thin film PbTiO3, which exhibited a striped nanoscale domain pattern on a high-miscut (001) SrTiO3 substrate. By converting the reconstructed BPP phase image to picometer-scale ionic displacements in the polar unit cell, a quantitative polarization map was made that was consistent with other characterization. The spatial resolution of 5.7 nm demonstrated here establishes BPP as an important tool for nanoscale ferroelectric domain imaging, especially in complex environments accessible with hard x rays.

  14. Electric field and temperature scaling of polarization reversal in silicon doped hafnium oxide ferroelectric thin films

    International Nuclear Information System (INIS)

    Zhou, Dayu; Guan, Yan; Vopson, Melvin M.; Xu, Jin; Liang, Hailong; Cao, Fei; Dong, Xianlin; Mueller, Johannes; Schenk, Tony; Schroeder, Uwe

    2015-01-01

    HfO 2 -based binary lead-free ferroelectrics show promising properties for non-volatile memory applications, providing that their polarization reversal behavior is fully understood. In this work, temperature-dependent polarization hysteresis measured over a wide applied field range has been investigated for Si-doped HfO 2 ferroelectric thin films. Our study indicates that in the low and medium electric field regimes (E < twofold coercive field, 2E c ), the reversal process is dominated by the thermal activation on domain wall motion and domain nucleation; while in the high-field regime (E > 2E c ), a non-equilibrium nucleation-limited-switching mechanism dominates the reversal process. The optimum field for ferroelectric random access memory (FeRAM) applications was determined to be around 2.0 MV/cm, which translates into a 2.0 V potential applied across the 10 nm thick films

  15. Oxygen tracer studies of ferroelectric fatigue in Pb(Zr,Ti)O3 thin films

    International Nuclear Information System (INIS)

    Schloss, Lawrence F.; McIntyre, Paul C.; Hendrix, Bryan C.; Bilodeau, Steven M.; Roeder, Jeffrey F.; Gilbert, Stephen R.

    2002-01-01

    Long-range oxygen motion has been observed in Pt/Pb(Zr,Ti)O 3 /Ir thin-film structures after electrical fatigue cycling at room temperature. Through an exchange anneal, isotopic 18 O was incorporated as a tracer into bare Pb(Zr,Ti)O 3 (PZT) films, allowing secondary ion mass spectrometry measurements of the tracer profile evolution as a function of the number of polarization reversals. Observation of 18 O tracer redistribution during voltage cycling, which is presumably mediated by oxygen vacancy motion, was found to be strongly dependent upon the thermal history of the film. However, there was no strong correlation between the extent of 18 O tracer redistribution and the extent of polarization suppression induced by voltage cycling. Our results suggest that oxygen vacancy motion plays, at most, a secondary role in ferroelectric fatigue of PZT thin films

  16. Hot plate annealing at a low temperature of a thin ferroelectric P(VDF-TrFE) film with an improved crystalline structure for sensors and actuators.

    Science.gov (United States)

    Mahdi, Rahman Ismael; Gan, W C; Abd Majid, W H

    2014-10-14

    Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  17. Comment on 'extrinsic versus intrinsic ferroelectric switching : experimental investigations using ultra-thin PVDF Langmuir-Blodgett films'

    NARCIS (Netherlands)

    Naber, R.C.G.; Blom, P.W.M.; de Leeuw, DM

    2006-01-01

    Previous work on ultra-thin P(VDF-TrFE) Langmuir-Blodgett films has indicated a transition from extrinsic to intrinsic ferroelectric switching. The lack of several key features of intrinsic switching in the experimental work reported by Kliem et al argues against intrinsic switching. In this Comment

  18. On bistable states retention in ferroelectric Langmuir-Blodgett films

    Science.gov (United States)

    Geivandov, A. R.; Palto, S. P.; Yudin, S. G.; Fridkin, V. M.; Blinov, L. M.; Ducharme, S.

    2003-08-01

    A new insight into the nature of ferroelectricity is emerging from the study of ultra-thin ferroelectric films prepared of poly(vinylidene fluoride with trifluoroethylene) copolymer using Langmuir-Blodgett (LB) technique. Unique properties of these films indicate the existence of two-dimensional ferroelectricity. The retention of two polarized states in ferroelectric polymer LB films is studied using nonlinear dielectric spectroscopy. The technique is based on phase sensitive measurements of nonlinear dielectric spectroscopy. The amplitude of the current response at the 2nd harmonic of the applied voltage is proportional to the magnitude of the remnant polarization, while its phase gives the sign. We have found that 10 - 20 mm thick LB films can show fast switching time and long retention of the two polarized states. Nevertheless, LB films show a pronounced asymmetry in switching to the opposite states. Possible mechanisms of such behavior are discussed.

  19. Enhancement of the saturation mobility in a ferroelectric-gated field-effect transistor by the surface planarization of ferroelectric film

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woo Young, E-mail: semigumi@kaist.ac.kr [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Jeon, Gwang-Jae; Kang, In-Ku; Shim, Hyun Bin; Lee, Hee Chul [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2015-09-30

    Ferroelectricity refers to the property of a dielectric material to undergo spontaneous polarization which originates from the crystalline phase. Hence, ferroelectric materials have a certain degree of surface roughness when they are formed as a thin film. A high degree of surface roughness may cause unintended phenomena when the ferroelectric material is used in electronic devices. Specifically, the quality of subsequently deposited film could be affected by the rough surface. The present study reports that the surface roughness of ferroelectric polymer film can be reduced by a double-spin-coating method of a solution, with control of the solubility of the solution. At an identical thickness of 350 nm, double-spin-coated ferroelectric film has a root-mean-square roughness of only 3 nm, while for single-spin-coated ferroelectric film this value is approximately 16 nm. A ferroelectric-gated field-effect transistor was fabricated using the proposed double-spin-coating method, showing a maximum saturation mobility as much as seven-fold than that of a transistor fabricated with single-spin-coated ferroelectric film. The enhanced saturation mobility could be explained by the Poole–Frenkel conduction mechanism. The proposed method to reduce the surface roughness of ferroelectric film would be useful for high performance organic electronic devices, including crystalline-phase dielectric film. - Highlights: • Single and double-layer solution-processed polymer ferroelectric films were obtained. • Adjusting the solvent solubility allows making double-layer ferroelectric (DF) films. • The DF film has a smoother surface than single-layer ferroelectric (SF) film. • DF-gated transistor has faster saturation mobility than SF-based transistor. • Solvent solubility adjustment led to higher performance organic devices.

  20. Microstructure research for ferroelectric origin in the strained Hf0.5Zr0.5O2 thin film via geometric phase analysis

    Science.gov (United States)

    Bi, Han; Sun, Qingqing; Zhao, Xuebing; You, Wenbin; Zhang, David Wei; Che, Renchao

    2018-04-01

    Recently, non-volatile semiconductor memory devices using a ferroelectric Hf0.5Zr0.5O2 film have been attracting extensive attention. However, at the nano-scale, the phase structure remains unclear in a thin Hf0.5Zr0.5O2 film, which stands in the way of the sustained development of ferroelectric memory nano-devices. Here, a series of electron microscopy evidences have illustrated that the interfacial strain played a key role in inducing the orthorhombic phase and the distorted tetragonal phase, which was the origin of the ferroelectricity in the Hf0.5Zr0.5O2 film. Our results provide insight into understanding the association between ferroelectric performances and microstructures of Hf0.5Zr0.5O2-based systems.

  1. Miniaturized and reconfigurable notch antenna based on a BST ferroelectric thin film

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Hung Viet [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); CEA-LETI, Minatec, 17 avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Benzerga, Ratiba, E-mail: ratiba.benzerga@univ-rennes1.fr [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); Borderon, Caroline [IETR, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes (France); Delaveaud, Christophe [CEA-LETI, Minatec, 17 avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Sharaiha, Ala [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); Renoud, Raphael [IETR, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes (France); Paven, Claire Le [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); Pavy, Sabrina; Nadaud, Kevin; Gundel, Hartmut W. [IETR, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes (France)

    2015-07-15

    Highlights: • A miniature and agile antenna based on a BST MIM capacitor is simulated and made. • Mn{sup 2+} doped BST thin films are synthesized by chemical deposition and spin coating. • Permittivity and losses of the BST thin film are respectively 225 and 0.02 at 1 GHz. • A miniaturization rate of 70% is obtained with a MIM capacitance of 3.7 pF. • A frequency tunability of 14.5% and a tunability performance of 0.04 are measured. - Abstract: This work deals with the design, realization and characterization of a miniature and frequency agile antenna based on a ferroelectric Ba{sub 0,80}Sr{sub 0,20}TiO{sub 3} thin film. The notch antenna is loaded with a variable metal/insulator/metal (MIM) capacitor and is achieved by a monolithic method. The MIM capacitance is 3.7 pF, which results in a resonant frequency of 670 MHz compared to 2.25 GHz for the unloaded simulated antenna; the resulting miniaturization rate is 70%. The characterization of the antenna prototype shows a frequency tunable rate of 14.5% under an electric field of 375 kV/cm, with a tunability performance η = 0.04.

  2. Growth of strained, ferroelectric NaNbO{sub 3} thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sellmann, Jan; Schwarzkopf, Jutta; Duk, Andreas; Kwasniewski, Albert; Schmidbauer, Martin; Fornari, Roberto [IKZ, Berlin (Germany)

    2012-07-01

    Due to its promising ferro-/piezoelectric properties and high Curie temperature NaNbO{sub 3} has attracted much attention. In contrast to bulk crystals, thin epitaxial films may incorporate and maintain a certain compressive or tensile lattice strain, depending on the used substrate/film combination. This deformation of the crystal lattice is known to strongly influence the ferroelectric properties of perovskites. In the case of NaNbO{sub 3} compressive strain is achieved in films deposited on NdGaO{sub 3} and SrTiO{sub 3} substrates while deposition on DyScO{sub 3} and TbScO{sub 3} leads to tensile in-plane strain. In order to characterize and practically apply the ferroelectric films, it is necessary to embed them in a capacitor structure for which we use pseudomorphically grown SrRuO{sub 3} as bottom electrodes. We report on the deposition of SrRuO{sub 3} and NaNbO{sub 3} single layers on SrTiO{sub 3}, DyScO{sub 3}, TbScO{sub 3} and NbGaO{sub 3} substrates by means of pulsed laser deposition. By adjusting the substrate temperature, the oxygen partial pressure and the laser frequency we have successfully deposited smooth, strained, single phase NaNbO{sub 3} thin films. Investigations of the films by atomic force microscopy and high resolution X-ray diffraction reveal the dependence of the surface morphology and the incorporated lattice strain on the deposition parameters and the lattice mismatch, respectively. All films exhibit piezoelectric properties, as proven by piezoresponse force microscopy.

  3. Development of highly-ordered, ferroelectric inverse opal films using sol gel infiltration

    Science.gov (United States)

    Matsuura, N.; Yang, S.; Sun, P.; Ruda, H. E.

    2005-07-01

    Highly-ordered, ferroelectric, Pb-doped Ba0.7Sr0.3TiO3, inverse opal films were fabricated by spin-coating a sol gel precursor into a polystyrene artificial opal template followed by heat treatment. Thin films of the ferroelectric were independently studied and were shown to exhibit good dielectric properties and high refractive indices. The excellent quality of the final inverse opal film using this spin-coating infiltration method was confirmed by scanning electron microscopy images and the good correspondence between optical reflection data and theoretical simulations. Using this method, the structural and material parameters of the final ferroelectric inverse opal film were easily adjusted by template heating and through repeated infiltrations, without changes in the initial template or precursor. Also, crack-free inverse opal thin films were fabricated over areas comparable to that of the initial crack-free polystyrene template (˜100 by 100 μm2).

  4. Silicon-integrated thin-film structure for electro-optic applications

    Science.gov (United States)

    McKee, Rodney A.; Walker, Frederick Joseph

    2000-01-01

    A crystalline thin-film structure suited for use in any of an number of electro-optic applications, such as a phase modulator or a component of an interferometer, includes a semiconductor substrate of silicon and a ferroelectric, optically-clear thin film of the perovskite BaTiO.sub.3 overlying the surface of the silicon substrate. The BaTiO.sub.3 thin film is characterized in that substantially all of the dipole moments associated with the ferroelectric film are arranged substantially parallel to the surface of the substrate to enhance the electro-optic qualities of the film.

  5. Integration and High-Temperature Characterization of Ferroelectric Vanadium-Doped Bismuth Titanate Thin Films on Silicon Carbide

    Science.gov (United States)

    Ekström, Mattias; Khartsev, Sergiy; Östling, Mikael; Zetterling, Carl-Mikael

    2017-07-01

    4H-SiC electronics can operate at high temperature (HT), e.g., 300°C to 500°C, for extended times. Systems using sensors and amplifiers that operate at HT would benefit from microcontrollers which can also operate at HT. Microcontrollers require nonvolatile memory (NVM) for computer programs. In this work, we demonstrate the possibility of integrating ferroelectric vanadium-doped bismuth titanate (BiTV) thin films on 4H-SiC for HT memory applications, with BiTV ferroelectric capacitors providing memory functionality. Film deposition was achieved by laser ablation on Pt (111)/TiO2/4H-SiC substrates, with magnetron-sputtered Pt used as bottom electrode and thermally evaporated Au as upper contacts. Film characterization by x-ray diffraction analysis revealed predominately (117) orientation. P- E hysteresis loops measured at room temperature showed maximum 2 P r of 48 μC/cm2, large enough for wide read margins. P- E loops were measurable up to 450°C, with losses limiting measurements above 450°C. The phase-transition temperature was determined to be about 660°C from the discontinuity in dielectric permittivity, close to what is achieved for ceramics. These BiTV ferroelectric capacitors demonstrate potential for use in HT NVM applications for SiC digital electronics.

  6. Anelastic deformation of Pb(Zr,Ti)O3 thin films by non-180 deg. ferroelectric domain wall movements during nanoindentation

    International Nuclear Information System (INIS)

    Alguero, M.; Bushby, A.J.; Reece, M.J.; Seifert, A.

    2002-01-01

    Lead zirconate titanate Pb(Zr,Ti)O 3 ferroelectric thin films show significant anelastic deformation when indented with spherical tipped indenters. Experiments on films with different Zr/Ti ratio and a mixed , preferred crystallographic orientation have shown that there is a good agreement between the anelastic deformation and the maximum strain achievable by non-180 deg. domain wall movement. An expected increase of the indentation stiffness of the films also accompanies the anelastic deformation because of the single crystal elastic anisotropy. All these observations seem to indicate that non-180 deg. ferroelectric domain wall movements occur under indentation stresses and cause anelasticity. Stresses for maximum anelastic deformation are compared with those for recently reported stress-induced depolarization

  7. Two-dimensional ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Blinov, L M; Fridkin, Vladimir M; Palto, Sergei P [A.V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russian Federaion (Russian Federation); Bune, A V; Dowben, P A; Ducharme, Stephen [Department of Physics and Astronomy, Behlen Laboratory of Physics, Center for Materials Research and Analysis, University of Nebraska-Linkoln, Linkoln, NE (United States)

    2000-03-31

    The investigation of the finite-size effect in ferroelectric crystals and films has been limited by the experimental conditions. The smallest demonstrated ferroelectric crystals had a diameter of {approx}200 A and the thinnest ferroelectric films were {approx}200 A thick, macroscopic sizes on an atomic scale. Langmuir-Blodgett deposition of films one monolayer at a time has produced high quality ferroelectric films as thin as 10 A, made from polyvinylidene fluoride and its copolymers. These ultrathin films permitted the ultimate investigation of finite-size effects on the atomic thickness scale. Langmuir-Blodgett films also revealed the fundamental two-dimensional character of ferroelectricity in these materials by demonstrating that there is no so-called critical thickness; films as thin as two monolayers (1 nm) are ferroelectric, with a transition temperature near that of the bulk material. The films exhibit all the main properties of ferroelectricity with a first-order ferroelectric-paraelectric phase transition: polarization hysteresis (switching); the jump in spontaneous polarization at the phase transition temperature; thermal hysteresis in the polarization; the increase in the transition temperature with applied field; double hysteresis above the phase transition temperature; and the existence of the ferroelectric critical point. The films also exhibit a new phase transition associated with the two-dimensional layers. (reviews of topical problems)

  8. Comment on 'Extrinsic versus intrinsic ferroelectric switching: experimental investigations using ultra-thin PVDF Langmuir-Blodgett films'

    International Nuclear Information System (INIS)

    Naber, R C G; Blom, P W M; Leeuw, D M de

    2006-01-01

    Previous work on ultra-thin P(VDF-TrFE) Langmuir-Blodgett films has indicated a transition from extrinsic to intrinsic ferroelectric switching. The lack of several key features of intrinsic switching in the experimental work reported by Kliem et al argues against intrinsic switching. In this Comment we discuss two published papers and new experimental results that support a lack of intrinsic switching and point to the conclusion that the thickness dependence of the Langmuir-Blodgett films is due to the influence of the electrode interfaces. (comment)

  9. Down-conversion luminescence and its temperature-sensing properties from Er3+-doped sodium bismuth titanate ferroelectric thin films

    Science.gov (United States)

    Wang, Shanshan; Zheng, Shanshan; Zhou, Hong; Pan, Anlian; Wu, Guangheng; Liu, Jun-ming

    2015-11-01

    Here, we demonstrate outstanding temperature-sensing properties from Na0.5Bi0.49Er0.01TiO3 (NBT:Er) thin films. The perovskite phase for them is stable in the temperature range from 80 to 440 K. Interestingly, the Er doping enhances the ferroelectric polarization and introduces local dipolar, which are positive for temperature sensing. Pumped by a 488-nm laser, the NBT:Er thin films show strong green luminescence with two bands around 525 and 548 nm. The intensity ratio I 525/ I 548 can be used for temperature sensing, and the maximum sensitivity is about 2.3 × 10-3 K-1, higher than that from Er-doped silicon oxide. These suggest NBT:Er thin film is a promising candidate for temperature sensor.

  10. Analysis and Optimization of Thin Film Ferroelectric Phase Shifters

    Science.gov (United States)

    Romanofsky, Robert R.; VanKeuls, Fred W.; Warner, Joseph D.; Mueller, Carl H.; Alterovitz, Samuel A.; Miranda, Felix A.; Qureshi, A. Haq; Romanofsky, Robert R. (Technical Monitor)

    2000-01-01

    Microwave phase shifters have been fabricated from (YBa2Cu3O(7-delta) or Au)/SrTiO3 and Au/Ba(x)Sr(1-x)TiO3 films on LaAlO3 and MgO substrates. These coupled microstrip devices rival the performance of their semiconductor counter-parts parts at Ku- and K-band frequencies. Typical insertion loss for room temperature ferroelectric phase shifters at K-band is approximately equal 5 dB. An experimental and theoretical investigation of these novel devices explains the role of the ferroelectric film in overall device performance. A roadmap to the development of a 3 dB insertion loss phase shifter that would enable a new type of phased array antenna is discussed.

  11. Nanoscale Ferroelectric Switchable Polarization and Leakage Current Behavior in (Ba0.50Sr0.50(Ti0.80Sn0.20O3 Thin Films Prepared Using Chemical Solution Deposition

    Directory of Open Access Journals (Sweden)

    Venkata Sreenivas Puli

    2015-01-01

    Full Text Available Nanoscale switchable ferroelectric (Ba0.50Sr0.50(Ti0.80Sn0.20O3-BSTS polycrystalline thin films with a perovskite structure were prepared on Pt/TiOx/SiO2/Si substrate by chemical solution deposition. X-ray diffraction (XRD spectra indicate that a cubic perovskite crystalline structure and Raman spectra revealed that a tetragonal perovskite crystalline structure is present in the thin films. Sr2+ and Sn4+ cosubstituted film exhibited the lowest leakage current density. Piezoresponse Force Microscopy (PFM technique has been employed to acquire out-of-plane (OPP piezoresponse images and local piezoelectric hysteresis loop in polycrystalline BSTS films. PFM phase and amplitude images reveal nanoscale ferroelectric switching behavior at room temperature. Square patterns with dark and bright contrasts were written by local poling and reversible nature of the piezoresponse behavior was established. Local piezoelectric butterfly amplitude and phase hysteresis loops display ferroelectric nature at nanoscale level. The significance of this paper is to present ferroelectric/piezoelectric nature in present BSTS films at nanoscale level and corroborating ferroelectric behavior by utilizing Raman spectroscopy. Thus, further optimizing physical and electrical properties, BSTS films might be useful for practical applications which include nonvolatile ferroelectric memories, data-storage media, piezoelectric actuators, and electric energy storage capacitors.

  12. Enhanced Switchable Ferroelectric Photovoltaic Effects in Hexagonal Ferrite Thin Films via Strain Engineering.

    Science.gov (United States)

    Han, Hyeon; Kim, Donghoon; Chu, Kanghyun; Park, Jucheol; Nam, Sang Yeol; Heo, Seungyang; Yang, Chan-Ho; Jang, Hyun Myung

    2018-01-17

    Ferroelectric photovoltaics (FPVs) are being extensively investigated by virtue of switchable photovoltaic responses and anomalously high photovoltages of ∼10 4 V. However, FPVs suffer from extremely low photocurrents due to their wide band gaps (E g ). Here, we present a promising FPV based on hexagonal YbFeO 3 (h-YbFO) thin-film heterostructure by exploiting its narrow E g . More importantly, we demonstrate enhanced FPV effects by suitably exploiting the substrate-induced film strain in these h-YbFO-based photovoltaics. A compressive-strained h-YbFO/Pt/MgO heterojunction device shows ∼3 times enhanced photovoltaic efficiency than that of a tensile-strained h-YbFO/Pt/Al 2 O 3 device. We have shown that the enhanced photovoltaic efficiency mainly stems from the enhanced photon absorption over a wide range of the photon energy, coupled with the enhanced polarization under a compressive strain. Density functional theory studies indicate that the compressive strain reduces E g substantially and enhances the strength of d-d transitions. This study will set a new standard for determining substrates toward thin-film photovoltaics and optoelectronic devices.

  13. Investigations on the effects of electrode materials on the device characteristics of ferroelectric memory thin film transistors fabricated on flexible substrates

    Science.gov (United States)

    Yang, Ji-Hee; Yun, Da-Jeong; Seo, Gi-Ho; Kim, Seong-Min; Yoon, Myung-Han; Yoon, Sung-Min

    2018-03-01

    For flexible memory device applications, we propose memory thin-film transistors using an organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] gate insulator and an amorphous In-Ga-Zn-O (a-IGZO) active channel. The effects of electrode materials and their deposition methods on the characteristics of memory devices exploiting the ferroelectric field effect were investigated for the proposed ferroelectric memory thin-film transistors (Fe-MTFTs) at flat and bending states. It was found that the plasma-induced sputtering deposition and mechanical brittleness of the indium-tin oxide (ITO) markedly degraded the ferroelectric-field-effect-driven memory window and bending characteristics of the Fe-MTFTs. The replacement of ITO electrodes with metal aluminum (Al) electrodes prepared by plasma-free thermal evaporation greatly enhanced the memory device characteristics even under bending conditions owing to their mechanical ductility. Furthermore, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) was introduced to achieve robust bending performance under extreme mechanical stress. The Fe-MTFTs using PEDOT:PSS source/drain electrodes were successfully fabricated and showed the potential for use as flexible memory devices. The suitable choice of electrode materials employed for the Fe-MTFTs is concluded to be one of the most important control parameters for highly functional flexible Fe-MTFTs.

  14. Crystallinity and electrical properties of neodymium-substituted bismuth titanate thin films

    International Nuclear Information System (INIS)

    Chen, Y.-C.; Hsiung, C.-P.; Chen, C.-Y.; Gan, J.-Y.; Sun, Y.-M.; Lin, C.-P.

    2006-01-01

    We report on the properties of Nd-substituted bismuth titanate Bi 4-x Nd x Ti 3 O 12 (BNdT) thin films for ferroelectric non-volatile memory applications. The Nd-substituted bismuth titanate thin films fabricated by modified chemical solution deposition technique showed much improved properties compared to pure bismuth titanate. A pyrochlore free crystalline phase was obtained at a low annealing temperature of 640 deg. C and grain size was found to be considerably increased as the annealing temperature increased. The film properties were found to be strongly dependent on the Nd content and annealing temperatures. The measured dielectric constant of BNdT thin films was in the range 172-130 for Bi 4-x Nd x Ti 3 O 12 with x 0.0-0.75. Ferroelectric properties of Nd-substituted bismuth titanate thin films were significantly improved compared to pure bismuth titanate. For example, the observed 2P r and E c for Bi 3.25 Nd 0.75 Ti 3 O 12 , annealed at 680 deg. C, were 38 μC/cm 2 and 98 kV/cm, respectively. The improved microstructural and ferroelectric properties of BNdT thin films suggest their suitability for high density ferroelectric random access memory applications

  15. Ferroelectrics onto silicon prepared by chemical solution deposition methods: from the thin film to the self-assembled systems

    Directory of Open Access Journals (Sweden)

    Calzada, M. L.

    2006-06-01

    Full Text Available The work of the authors during the last years on ferroelectric thin and ultra-thin films deposited by Chemical Solution Deposition (CSD onto silicon based substrates is reviewed in this paper. Ferroelectric layers integrated with silicon substrates have potential use in the new micro/nanoelectronic devices. Two hot issues are here considered: 1 the use of low processing temperatures of the ferroelectric film, with the objective of not producing any damage on the different elements of the device heterostructure, and 2 the downscaling of the ferroelectric material with the aim of achieving the high densities of integration required in the next generation of nanoelectronic devices. The UV-assisted Rapid Thermal Processing has successfully been used in our laboratory for the fabrication of ferroelectric films at low temperatures. Preliminary results on the CSD preparation of nanosized ferroelectric structures are shown.

    Este artículo revisa el trabajo realizado por los autores durante los últimos años sobre lámina delgada y ultra-delgada ferroeléctrica preparada mediante el depósito químico de disoluciones (CSD sobre substratos de silicio. Las películas ferroeléctricas integradas con silicio tienen potenciales usos en los nuevos dispositivos micro/nanoelectrónicos. Dos aspectos claves son aquí considerados: 1 el uso de bajas temperaturas de procesado de la lámina ferroeléctrica, con el fin de no dañar los diferentes elementos que forman la heteroestructura del dispositivo y 2 la disminución de tamaño del material ferroeléctrico con el fin de conseguir las altas densidades de integración requeridas en la próxima generación de dispositivos nanoelectróncos. Los procesos térmicos rápidos asistidos con irradiación UV se están usando en nuestro laboratorio para conseguir la fabricación del material ferroeléctrico a temperaturas bajas compatibles con la tecnología del silicio. Se muestran resultados preliminares sobre

  16. Thickness dependence of the switching voltage in all-oxide ferroelectric thin-film capacitors prepared by pulsed laser deposition

    NARCIS (Netherlands)

    Cillessen, J.F.M.; Prins, M.W.J.; Wolf, R.M.

    1997-01-01

    Thin-film ferroelectric capacitors consisting of PbZr0.53Ti0.47O3 sandwiched between La0.5Sr0.5CoO3 electrodes have been deposited using pulsed laser deposition. The combination of oxidic perovskite-type materials results in capacitors with a coercive field (Ec) which is comparable with values for

  17. Structure and switching of in-plane ferroelectric nano-domains in strained PbxSr1-xTiO3 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Matzen, Sylivia [University of Groningen, The Netherlands; Nesterov, Okeksiy [ORNL; Rispens, Gregory [University of Groningen, The Netherlands; Heuver, J. A. [University of Groningen, The Netherlands; Bark, C [University of Wisconsin, Madison; Biegalski, Michael D [ORNL; Christen, Hans M [ORNL; Noheda, Beatriz [University of Groningen, The Netherlands

    2014-01-01

    Nanoscale ferroelectrics, the active elements of a variety of nanoelectronic devices, develop denser and richer domain structures than the bulk counterparts. With shrinking device sizes understanding and controlling domain formation in nanoferroelectrics is being intensely studied. Here we show that a precise control of the epitaxy and the strain allows stabilizing a hierarchical domain architecture in PbxSr1-xTiO3 thin films, showing periodic, purely in-plane polarized, ferroelectric nano-domains that can be switched by a scanning probe.

  18. Piezoelectric MEMS: Ferroelectric thin films for MEMS applications

    Science.gov (United States)

    Kanno, Isaku

    2018-04-01

    In recent years, piezoelectric microelectromechanical systems (MEMS) have attracted attention as next-generation functional microdevices. Typical applications of piezoelectric MEMS are micropumps for inkjet heads or micro-gyrosensors, which are composed of piezoelectric Pb(Zr,Ti)O3 (PZT) thin films and have already been commercialized. In addition, piezoelectric vibration energy harvesters (PVEHs), which are regarded as one of the key devices for Internet of Things (IoT)-related technologies, are promising future applications of piezoelectric MEMS. Significant features of piezoelectric MEMS are their simple structure and high energy conversion efficiency between mechanical and electrical domains even on the microscale. The device performance strongly depends on the function of the piezoelectric thin films, especially on their transverse piezoelectric properties, indicating that the deposition of high-quality piezoelectric thin films is a crucial technology for piezoelectric MEMS. On the other hand, although the difficulty in measuring the precise piezoelectric coefficients of thin films is a serious obstacle in the research and development of piezoelectric thin films, a simple unimorph cantilever measurement method has been proposed to obtain precise values of the direct or converse transverse piezoelectric coefficient of thin films, and recently this method has become to be the standardized testing method. In this article, I will introduce fundamental technologies of piezoelectric thin films and related microdevices, especially focusing on the deposition of PZT thin films and evaluation methods for their transverse piezoelectric properties.

  19. Tensile strain effect in ferroelectric perovskite oxide thin films on spinel magnesium aluminum oxide substrate

    Science.gov (United States)

    Zhou, Xiaolan

    Ferroelectrics are used in FeRAM (Ferroelectric random-access memory). Currently (Pb,Zr)TiO3 is the most common ferroelectric material. To get lead-free and high performance ferroelectric material, we investigated perovskite ferroelectric oxides (Ba,Sr)TiO3 and BiFeO3 films with strain. Compressive strain has been investigated intensively, but the effects of tensile strain on the perovskite films have yet to be explored. We have deposited (Ba,Sr)TiO3, BiFeO3 and related films by pulsed laser deposition (PLD) and analyzed the films by X-ray diffractometry (XRD), atomic force microscopy (AFM), etc. To obtain inherently fully strained films, the selection of the appropriate substrates is crucial. MgAl2O4 matches best with good quality and size, yet the spinel structure has an intrinsic incompatibility to that of perovskite. We introduced a rock-salt structure material (Ni 1-xAlxO1+delta) as a buffer layer to mediate the structural mismatch for (Ba,Sr)TiO3 films. With buffer layer Ni1-xAlxO1+delta, we show that the BST films have high quality crystallization and are coherently epitaxial. AFM images show that the films have smoother surfaces when including the buffer layer, indicating an inherent compatibility between BST-NAO and NAO-MAO. In-plane Ferroelectricity measurement shows double hysteresis loops, indicating an antiferroelectric-like behavior: pinned ferroelectric domains with antiparallel alignments of polarization. The Curie temperatures of the coherent fully strained BST films are also measured. It is higher than 900°C, at least 800°C higher than that of bulk. The improved Curie temperature makes the use of BST as FeRAM feasible. We found that the special behaviors of ferroelectricity including hysteresis loop and Curie temperature are due to inherent fully tensile strain. This might be a clue of physics inside ferroelectric stain engineering. An out-of-plane ferroelectricity measurement would provide a full whole story of the tensile strain. However, a

  20. Reversible and nonvolatile ferroelectric control of two-dimensional electronic transport properties of ZrCuSiAs-type copper oxyselenide thin films with a layered structure

    Science.gov (United States)

    Zhao, Xu-Wen; Gao, Guan-Yin; Yan, Jian-Min; Chen, Lei; Xu, Meng; Zhao, Wei-Yao; Xu, Zhi-Xue; Guo, Lei; Liu, Yu-Kuai; Li, Xiao-Guang; Wang, Yu; Zheng, Ren-Kui

    2018-05-01

    Copper-based ZrCuSiAs-type compounds of LnCuChO (Ln =Bi and lanthanides, Ch =S , Se, Te) with a layered crystal structure continuously attract worldwide attention in recent years. Although their high-temperature (T ≥ 300 K) electrical properties have been intensively studied, their low-temperature electronic transport properties are little known. In this paper, we report the integration of ZrCuSiAs-type copper oxyselenide thin films of B i0.94P b0.06CuSeO (BPCSO) with perovskite-type ferroelectric Pb (M g1 /3N b2 /3 ) O3-PbTi O3 (PMN-PT) single crystals in the form of ferroelectric field effect devices that allow us to control the electronic properties (e.g., carrier density, magnetoconductance, dephasing length, etc.) of BPCSO films in a reversible and nonvolatile manner by polarization switching at room temperature. Combining ferroelectric gating and magnetotransport measurements with the Hikami-Larkin-Nagaoka theory, we demonstrate two-dimensional (2D) electronic transport characteristics and weak antilocalization effect as well as strong carrier-density-mediated competition between weak antilocalization and weak localization in BPCSO films. Our results show that ferroelectric gating using PMN-PT provides an effective and convenient approach to probe the carrier-density-related 2D electronic transport properties of ZrCuSiAs-type copper oxyselenide thin films.

  1. Low temperature dielectric relaxation and charged defects in ferroelectric thin films

    Directory of Open Access Journals (Sweden)

    A. Artemenko

    2013-04-01

    Full Text Available We report a dielectric relaxation in BaTiO3-based ferroelectric thin films of different composition and with several growth modes: sputtering (with and without magnetron and sol-gel. The relaxation was observed at cryogenic temperatures (T < 100 K for frequencies from 100 Hz up to 10 MHz. This relaxation activation energy is always lower than 200 meV and is very similar to the relaxation that we reported in the parent bulk perovskites. Based on our Electron Paramagnetic Resonance (EPR investigation, we ascribe this dielectric relaxation to the hopping of electrons among Ti3+-V(O charged defects. Being dependent on the growth process and on the amount of oxygen vacancies, this relaxation can be a useful probe of defects in actual integrated capacitors with no need for specific shaping.

  2. Interaction between depolarization effects, interface layer, and fatigue behavior in PZT thin film capacitors

    Science.gov (United States)

    Böttger, U.; Waser, R.

    2017-07-01

    The existence of non-ferroelectric regions in ferroelectric thin films evokes depolarization effects leading to a tilt of the P(E) hysteresis loop. The analysis of measured hysteresis of lead zirconate titanate (PZT) thin films is used to determine a depolarization factor which contains quantitative information about interfacial layers as well as ferroelectrically passive zones in the bulk. The derived interfacial capacitance is smaller than that estimated from conventional extrapolation techniques. In addition, the concept of depolarization is used for the investigation of fatigue behavior of PZT thin films indicating that the mechanism of seed inhibition, which is responsible for the effect, occurs in the entire film.

  3. A Reconfigurable Coplanar Waveguide Bowtie Antenna Using an Integrated Ferroelectric Thin-Film Varactor

    Directory of Open Access Journals (Sweden)

    K. C. Pan

    2012-01-01

    Full Text Available A novel printed antenna with a frequency reconfigurable feed network is presented. The antenna consists of a bowtie structure patch radiating element in the inner space of an annulus that is on a nongrounded substrate with a ferroelectric (FE Barium Strontium Titanate (BST thin film. The bowtie patch is fed by a coplanar waveguide (CPW transmission line that also includes a CPW-based BST shunt varactor. Reconfiguration of the compact 8 mm × 8 mm system has been demonstrated by shifting the antenna system’s operating frequency 500 MHz in the 7–9 GHz band by applying a DC voltage bias.

  4. Subcritical switching dynamics and humidity effects in nanoscale studies of domain growth in ferroelectric thin films

    International Nuclear Information System (INIS)

    Blaser, Cédric; Paruch, Patrycja

    2015-01-01

    Ferroelectric domain switching in c-axis-oriented epitaxial Pb(Zr 0.2 Ti 0.8 )O 3 thin films was studied using biased scanning probe microscopy tips. While linear and logarithmic dependence of domain size on tip bias and writing time, respectively, are well known, we report an additional linear dependence on relative humidity in the 28–65% range. We map out the switched domain size as a function of both the tip bias and the applied pulse time and describe a growth-limited regime for very short pulses and a nucleation-limited regime for very low tip bias. Using ‘interrupted-switching’ measurements, we probe the nucleation regime with subcritical pulses and identify a surprisingly long relaxation time on the order of 100 ms, which we relate to ionic redistribution both on the surface and within the thin film itself. (paper)

  5. Silicon-doped hafnium oxide anti-ferroelectric thin films for energy storage

    Science.gov (United States)

    Ali, Faizan; Liu, Xiaohua; Zhou, Dayu; Yang, Xirui; Xu, Jin; Schenk, Tony; Müller, Johannes; Schroeder, Uwe; Cao, Fei; Dong, Xianlin

    2017-10-01

    Motivated by the development of ultracompact electronic devices as miniaturized energy autonomous systems, great research efforts have been expended in recent years to develop various types of nano-structural energy storage components. The electrostatic capacitors characterized by high power density are competitive; however, their implementation in practical devices is limited by the low intrinsic energy storage density (ESD) of linear dielectrics like Al2O3. In this work, a detailed experimental investigation of energy storage properties is presented for 10 nm thick silicon-doped hafnium oxide anti-ferroelectric thin films. Owing to high field induced polarization and slim double hysteresis, an extremely large ESD value of 61.2 J/cm3 is achieved at 4.5 MV/cm with a high efficiency of ˜65%. In addition, the ESD and the efficiency exhibit robust thermal stability in 210-400 K temperature range and an excellent endurance up to 109 times of charge/discharge cycling at a very high electric field of 4.0 MV/cm. The superior energy storage performance together with mature technology of integration into 3-D arrays suggests great promise for this recently discovered anti-ferroelectric material to replace the currently adopted Al2O3 in fabrication of nano-structural supercapacitors.

  6. Magnetoelastic coupling in multilayered ferroelectric/ferromagnetic thin films: A quantitative evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Chiolerio, A., E-mail: alessandro.chiolerio@iit.it [Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10129 Turin (Italy); Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, IT-10129 Turin (Italy); Quaglio, M. [Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, IT-10129 Turin (Italy); Lamberti, A. [Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10129 Turin (Italy); Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, IT-10129 Turin (Italy); Celegato, F. [Electromagnetism Division, INRIM, Strada delle Cacce 91, IT-10135 Turin (Italy); Balma, D.; Allia, P. [Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10129 Turin (Italy)

    2012-08-01

    The electrical control of magnetization in a thin film, achieved by means of magnetoelastic coupling between a ferroelectric and a ferromagnetic layer represents an attractive way to implement magnetic information storage and processing within logical architectures known as Magnetic Quantum Cellular Automata (MQCA). Such systems have been addressed as multiferroics. We exploited cost-effective techniques to realize multi-layered multiferroic systems, such as sol-gel deposition and RF sputtering, introducing a specific technique to control the crystal structure and film roughness effect on the magnetic domain wall motion and reconfiguration, induced by magnetoelastic coupling, by evaluating the 2-dimensional statistical properties of enhanced MFM matrices. A RF sputtered 50-nm-thick Co layer on a Si/SiO{sub 2}/Si{sub 3}N{sub 4}/Ti/Pt/PbTiO{sub 3}/Pb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3} substrate was realized, exploiting two differently engineered PZT nano-crystalline structures and the conditions leading to a favorable compromise in order to realize functional devices were elucidated.

  7. In situ 2D diffraction as a tool to characterize ferroelectric and piezoelectric thin films

    Science.gov (United States)

    Khamidy, N. I.; Kovacova, V.; Bernasconi, A.; Le Rhun, G.; Vaxelaire, N.

    2017-08-01

    In this paper the application of 2D x-ray diffraction (XRD2) as a technique to characterize in situ during electrical cycling the properties of a ferroelectric and piezoelectric thin film is discussed. XRD2 is one type of XRD on which a 2D detector is used instead of a point detector. This technique enables simultaneous recording of many sample information in a much shorter time compared to conventional XRD. The discussion is focused especially on the data processing technique of the huge data acquired. The methodology to calculate an effective piezoelectric coefficient, analyze the phase and texture, and estimate the domain size and shape is described in this paper. This methodology is then applied to a lead zirconate titanate (PZT) thin film at the morphotropic phase boundary (MPB) composition (i.e. Pb[Zr0.52Ti0.48]O3) with a preferred orientation of (1 0 0). The in situ XRD2 characterization was conducted in the European synchrotron radiation facility (ESRF) in Grenoble, France. Since a high-energy beam with vertical resolution as small as 100 nm was used, a cross-sectional scan of the sample was performed over the entire thickness of the film. From these experimental results, a better understanding on the piezoelectricity phenomena in PZT thin film at MPB composition were achieved, providing original feedback between the elaboration processes and functional properties of the film.

  8. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    Science.gov (United States)

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics. PMID:23884324

  9. Growth and physical properties of highly oriented La-doped (K,Na)NbO3 ferroelectric thin films

    International Nuclear Information System (INIS)

    Vendrell, X.; Raymond, O.; Ochoa, D.A.; García, J.E.; Mestres, L.

    2015-01-01

    Lead-free (K,Na)NbO 3 (KNN) and La doped (K,Na)NbO 3 (KNN-La) thin films are grown on SrTiO 3 substrates using the chemical solution deposition method. The effect of adding different amounts of Na and K excess (0–20 mol%) is investigated. The results confirm the necessity of adding 20 mol% excess amounts of Na and K precursor solutions in order to avoid the formation of the secondary phase, K 4 Nb 6 O 17 , as confirmed by X-ray diffraction and Raman spectroscopy. Moreover, when adding a 20 mol% of alkaline metal excess, the thin films are highly textured with out-of-plane preferential orientation in the [100] direction of the [100] orientation of the substrate. Doping with lanthanum results in a decrease of the leakage current density at low electric field, and an increase in the dielectric permittivity across the whole temperature range (80–380 K). Although the (100)-oriented KNN and KNN-La films exhibited rounded hysteresis loops, at low temperatures the films show the typical ferroelectric hysteresis loops. - Highlights: • (K 0.5 Na 0.5 )NbO 3 and [(K 0.5 Na 0.5 ) 0.985 La 0.005 ]NbO 3 thin films have been prepared. • The obtained thin films show an excellent (100) preferred orientation. • Doping with lanthanum results in a decrease of the leakage current density. • The dielectric properties are enhanced when doping with lanthanum

  10. Characterization of the effective electrostriction coefficients in ferroelectric thin films

    Science.gov (United States)

    Kholkin, A. L.; Akdogan, E. K.; Safari, A.; Chauvy, P.-F.; Setter, N.

    2001-06-01

    Electromechanical properties of a number of ferroelectric films including PbZrxTi1-xO3(PZT), 0.9PbMg1/3Nb2/3O3-0.1PbTiO3(PMN-PT), and SrBi2Ta2O9(SBT) are investigated using laser interferometry combined with conventional dielectric measurements. Effective electrostriction coefficients of the films, Qeff, are determined using a linearized electrostriction equation that couples longitudinal piezoelectric coefficient, d33, with the polarization and dielectric constant. It is shown that, in PZT films, electrostriction coefficients slightly increase with applied electric field, reflecting the weak contribution of non-180° domains to piezoelectric properties. In contrast, in PMN-PT and SBT films electrostriction coefficients are field independent, indicating the intrinsic nature of the piezoelectric response. The experimental values of Qeff are significantly smaller than those of corresponding bulk materials due to substrate clamping and possible size effects. Electrostriction coefficients of PZT layers are shown to depend strongly on the composition and preferred orientation of the grains. In particular, Qeff of (100) textured rhombohedral films (x=0.7) is significantly greater than that of (111) layers. Thus large anisotropy of the electrostrictive coefficients is responsible for recently observed large piezoelectric coefficients of (100) textured PZT films. Effective electrostriction coefficients obtained by laser interferometry allow evaluation of the electromechanical properties of ferroelectric films based solely on the dielectric parameters and thus are very useful in the design and fabrication of microsensors and microactuators.

  11. Dimensional scaling of perovskite ferroelectric thin films

    Science.gov (United States)

    Keech, Ryan R.

    Dimensional size reduction has been the cornerstone of the exponential improvement in silicon based logic devices for decades. However, fundamental limits in the device physics were reached ˜2003, halting further reductions in clock speed without significant penalties in power consumption. This has motivated the research into next generation transistors and switching devices to reinstate the scaling laws for clock speed. This dissertation aims to support the scaling of devices that are based on ferroelectricity and piezoelectricity and to provide a roadmap for the corresponding materials performance. First, a scalable growth process to obtain highly {001}-oriented lead magnesium niobate - lead titanate (PMN-PT) thin films was developed, motivated by the high piezoelectric responses observed in bulk single crystals. It was found that deposition of a 2-3 nm thick PbO buffer layer on {111} Pt thin film bottom electrodes, prior to chemical solution deposition of PMN-PT reduces the driving force for Pb diffusion from the PMN-PT to the bottom electrode, and facilitates nucleation of {001}-oriented perovskite grains. Energy dispersive spectroscopy demonstrated that up to 10% of the Pb from a PMN-PT precursor solution may diffuse into the bottom electrode. PMN-PT grains with a mixed {101}/{111} orientation in a matrix of Pb-deficient pyrochlore phase were then promoted near the interface. When this is prevented, phase pure films with {001} orientation with Lotgering factors of 0.98-1.0, can be achieved. The resulting films of only 300 nm in thickness exhibit longitudinal effective d33,f coefficients of ˜90 pm/V and strain values of ˜1% prior to breakdown. 300 nm thick epitaxial and polycrystalline lead magnesium niobate - lead titanate (70PMN-30PT) blanket thin films were studied for the relative contributions to property thickness dependence from interfacial and grain boundary low permittivity layers. Epitaxial PMN-PT films were grown on SrRuO 3 /(001)SrTiO3, while

  12. Proceedings of the 8th International Symposium on Applications of Ferroelectrics

    Science.gov (United States)

    Liu, M.; Safari, A.; Kingon, A.; Haertling, G.

    1993-02-01

    The eighth International Symposium on the Applications of Ferroelectrics was held in Greenville, SC, on August 30 to Sept 2, 1992. It was attended by approximately 260 scientists and engineers who presented nearly 200 oral and poster papers. The three plenary presentations covered ferroelectric materials which are currently moving into commercial exploitation or have strong potential to do so. These were (1) pyroelectric imaging, (2) ferroelectric materials integrated with silicon for use as micromotors and microsensors and (3) research activity in Japan on high permittivity materials for DRAM's. Invited papers covered such subjects as pyroelectric and electrooptic properties of thin films, photorefractive effects, ferroelectric polymers, piezoelectric transducers, processing of ferroelectrics, domain switching in ferroelectrics, thin film memories, thin film vacuum deposition techniques and the fabrication of chemically prepared PZT and PLZT thin films. The papers continued to reflect the large interest in ferroelectric thin films. It was encouraging that there have been substantial strides made in both the processing and understanding of the films in the last two years. It was equally clear, however, that much still remains to be done before reliable thin film devices will be available in the marketplace.

  13. Fabrication of Pb (Zr, Ti) O3 Thin Film for Non-Volatile Memory Device Application

    International Nuclear Information System (INIS)

    Mar Lar Win

    2011-12-01

    Ferroelectric lead zirconate titanate powder was composed of mainly the oxides of titanium, zirconium and lead. PZT powder was firstly prepared by thermal synthesis at different Zr/Ti ratios with various sintering temperatures. PZT thin film was fabricated on SiO2/Si substrate by using thermal evaporation method. Physical and elemental analysis were carried out by using SEM, EDX and XRD The ferroelectric properties and the switching behaviour of the PZT thin films were investigated. The ferroelectric properties and switching properties of the PZT thin film (near morphotropic phase boundary sintered at 800 C) could function as a nonvolatile memory.

  14. Ferroelectric Thin Films III, Symposium Held in San Francisco, California on April 13 - 16, 1993. Materials Research Society Symposium Proceedings, Volume 310

    Science.gov (United States)

    1993-04-16

    Publication Data Ferroelectric thin films III : symposium held April 13-16, 1993, San Francisco,California, U.S.A. / editors, Bruce A. Turtle , Edwlrd R...All solutions were placed in a modified Collison Nebulizer which generated the droplets in an oxygen carrier gas. The droplets were transported into

  15. Structural and ferroelectric properties of Sr1−xBaxBi2Nb2O9 thin films obtained by dip-coating

    Directory of Open Access Journals (Sweden)

    Y. González-Abreu

    2017-10-01

    Full Text Available The paper presents the structural and ferroelectric results for Sr1−xBaxBi2Nb2O9(x=0.30; 0.85 thin films, which were obtained by using dip-coating. The solutions containing the desirable ions were prepared from the powders of the previous studied ceramic samples. The films were deposited at room temperature on Fluorine-doped Tin Oxide (FTO substrates and submitted to a heat treatment for crystallization. The films were characterized by using scanning microscopy electronic, energy dispersive spectroscopy and ellipsometry. Hysteresis ferroelectric loops were obtained, at room temperature, by using a Sawyer-Tower circuit at several frequencies. A well-defined grain structure was observed for both compositions. The energy dispersive spectroscopy (EDS measurements revealed the presence of the corresponding elements from the chemical composition of the ceramic systems. The band-gap energy was around 3.3eV for both samples. Typical hysteresis loops for normal and relaxor ferroelectrics were obtained for x=0.30 and 0.85, respectively.

  16. Superdomain dynamics in ferroelectric-ferroelastic films: Switching, jamming, and relaxation

    Science.gov (United States)

    Scott, J. F.; Hershkovitz, A.; Ivry, Y.; Lu, H.; Gruverman, A.; Gregg, J. M.

    2017-12-01

    Recent experimental work shows that ferroelectric switching can occur in large jumps in which ferroelastic superdomains switch together, rather than having the numerous smaller ferroelectric domains switch within them. In this sense, the superdomains play a role analogous to that of Abrikosov vortices in thin superconducting films under the Kosterlitz-Thouless framework, which control the dynamics more than individual Cooper pairs within them do. Here, we examine the dynamics of ferroelastic superdomains in ferroelastic ferroelectrics and their role in switching devices such as memories. Jamming of ferroelectric domains in thin films has revealed an unexpected time dependence of t-1/4 at long times (hours), but it is difficult to discriminate between power-law and exponential relaxation. Other aspects of this work, including spatial period doubling of domains, led to a description of ferroelastic domains as nonlinear processes in a viscoelastic medium, which produce folding and metastable kinetically limited states. This ¼ exponent is a surprising agreement with the well-known value of ¼ for coarsening dynamics in viscoelastic media. We try to establish a link between these two processes, hitherto considered unrelated, and with superdomains and domain bundles. We note also that high-Tc superconductors share many of the ferroelastic domain properties discussed here and that several new solar cell materials and metal-insulator transition systems are ferroelastic.

  17. Stacking effect on the ferroelectric properties of PZT/PLZT multilayer thin films formed by photochemical metal-organic deposition

    International Nuclear Information System (INIS)

    Park, Hyeong-Ho; Park, Hyung-Ho; Hill, Ross H.

    2004-01-01

    The ferroelectric properties of lead zirconate titanate (PZT) and lanthanum-doped lead zirconate titanate (PLZT) multilayer films formed by photochemical metal-organic deposition (PMOD) using photosensitive precursors have been characterized. The substitution of La for Pb was reported to induce improved ferroelectric properties, especially fatigue resistance, through the reduction of oxygen vacancies. The relation between La-substitution and the ferroelectric properties was investigated by characterization of the effect of the order of stacking four ferroelectric layers of PZT or PLZT in the multilayer films 4-PZT, PZT/2-PLZT/PZT, PLZT/2-PZT/PLZT, and 4-PLZT. The films with the PLZT layer at the top and bottom showed an improvement in the fatigue resistance. It was revealed that defect dipole such as O vacancy was reduced at the ferroelectric/Pt interface by doping with La. Also, the bottom layer, just on Pt substrate had a significant influence on the surface microstructure and growth orientation of ferroelectric film

  18. The Integration and Applications of Organic Thin Film Transistors and Ferroelectric Polymers

    Science.gov (United States)

    Hsu, Yu-Jen

    Organic thin film transistors and ferroelectric polymer (polyvinylidene difluoride) sheet material are integrated to form various sensors for stress/strain, acoustic wave, and Infrared (heat) sensing applications. Different from silicon-based transistors, organic thin film transistors can be fabricated and processed in room-temperature and integrated with a variety of substrates. On the other hand, polyvinylidene difluoride (PVDF) exhibits ferroelectric properties that are highly useful for sensor applications. The wide frequency bandwidth (0.001 Hz to 10 GHz), vast dynamic range (100n to 10M psi), and high elastic compliance (up to 3 percent) make PVDF a more suitable candidate over ceramic piezoelectric materials for thin and flexible sensor applications. However, the low Curie temperature may have impeded its integration with silicon technology. Organic thin film transistors, however, do not have the limitation of processing temperature, hence can serve as transimpedance amplifiers to convert the charge signal generated by PVDF into current signal that are more measurable and less affected by any downstream parasitics. Piezoelectric sensors are useful for a range of applications, but passive arrays suffer from crosstalk and signal attenuation which have complicated the development of array-based PVDF sensors. We have used organic field effect transistors, which are compatible with the low Curie temperature of a flexible piezoelectric polymer,PVDF, to monolithically fabricate transimpedance amplifiers directly on the sensor surface and convert the piezoelectric charge signal into a current signal which can be detected even in the presence of parasitic capacitances. The device couples the voltage generated by the PVDF film under strain into the gate of the organic thin film transistors (OFET) using an arrangement that allows the full piezoelectric voltage to couple to the channel, while also increasing the charge retention time. A bipolar detector is created by

  19. Strain-induced phenomenon in complex oxide thin films

    Science.gov (United States)

    Haislmaier, Ryan

    Complex oxide materials wield an immense spectrum of functional properties such as ferroelectricity, ferromagnetism, magnetoelectricity, optoelectricity, optomechanical, magnetoresistance, superconductivity, etc. The rich coupling between charge, spin, strain, and orbital degrees of freedom makes this material class extremely desirable and relevant for next generation electronic devices and technologies which are trending towards nanoscale dimensions. Development of complex oxide thin film materials is essential for realizing their integration into nanoscale electronic devices, where theoretically predicted multifunctional capabilities of oxides could add tremendous value. Employing thin film growth strategies such as epitaxial strain and heterostructure interface engineering can greatly enhance and even unlock novel material properties in complex oxides, which will be the main focus of this work. However, physically incorporating oxide materials into devices remains a challenge. While advancements in molecular beam epitaxy (MBE) of thin film oxide materials has led to the ability to grow oxide materials with atomic layer precision, there are still major limitations such as controlling stoichiometric compositions during growth as well as creating abrupt interfaces in multi-component layered oxide structures. The work done in this thesis addresses ways to overcome these limitations in order to harness intrinsic material phenomena. The development of adsorption-controlled stoichiometric growth windows of CaTiO3 and SrTiO3 thin film materials grown by hybrid MBE where Ti is supplied using metal-organic titanium tetraisopropoxide material is thoroughly outlined. These growth windows enable superior epitaxial strain-induced ferroelectric and dielectric properties to be accessed as demonstrated by chemical, structural, electrical, and optical characterization techniques. For tensile strained CaTiO3 and compressive strained SrTiO 3 films, the critical effects of

  20. Tunable band gap in epitaxial ferroelectric Ho(Mn,Ga)O{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Daesu; Noh, Tae Won, E-mail: twnoh@snu.ac.kr [Center for Correlated Electron Systems, Institute for Basic Science, Seoul 151-742 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Choi, Woo Seok [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2016-05-09

    Ferroelectrics have recently attracted attention as a new class of materials for use in optical and photovoltaic devices. We studied the electronic properties in epitaxially stabilized ferroelectric hexagonal Ho(Mn{sub 1−x}Ga{sub x})O{sub 3} (x = 0, 0.33, 0.67, and 1) thin films. Our films exhibited systematic changes in electronic structures, such as bandgap and optical transitions, according to the Ga concentration. In particular, the bandgap increased systematically from 1.4 to 3.2 eV, including the visible light region, with increasing Ga concentration from x = 0 to 1. These systematic changes, attributed to lattice parameter variations in epitaxial Ho(Mn{sub 1−x}Ga{sub x})O{sub 3} films, should prove useful for the design of optoelectronic devices based on ferroelectrics.

  1. Highly polarized single-c-domain single-crystal Pb(Mn,Nb)O(3)-PZT thin films.

    Science.gov (United States)

    Wasa, Kiyotaka; Adachi, Hideaki; Nishida, Ken; Yamamoto, Takashi; Matsushima, Tomoaki; Kanno, Isaku; Kotera, Hidetoshi

    2012-01-01

    In-plane unstrained single-c-domain/single-crystal thin films of PZT-based ternary ferroelectric perovskite, ξPb(Mn,Nb)O3-(1 - ξ)PZT, were grown on SrRuO(3)/Pt/MgO substrates using magnetron sputtering followed by quenching. The sputtered unstrained thin films exhibit unique ferroelectric properties: high coercive field, Ec > 180 kV/cm, large remanent polarization, P(r) = 100 μC/cm(2), small relative dielectric constants, ε* = 100 to 150, high Curie temperature, Tc = ~600 °C, and bulk-like large transverse piezoelectric constants, e31,f = -12.0 C/m(2) for PZT(48/52) at ξ = 0.06. The unstrained thin films are an ideal structure to extract the bulk ferroelectric properties. Their micro-structures and ferroelectric properties are discussed in relation to the potential applications for piezoelectric MEMS. © 2012 IEEE

  2. Ion beam-based characterization of multicomponent oxide thin films and thin film layered structures

    International Nuclear Information System (INIS)

    Krauss, A.R.; Rangaswamy, M.; Lin, Yuping; Gruen, D.M.; Schultz, J.A.; Schmidt, H.K.; Chang, R.P.H.

    1992-01-01

    Fabrication of thin film layered structures of multi-component materials such as high temperature superconductors, ferroelectric and electro-optic materials, and alloy semiconductors, and the development of hybrid materials requires understanding of film growth and interface properties. For High Temperature Superconductors, the superconducting coherence length is extremely short (5--15 Angstrom), and fabrication of reliable devices will require control of film properties at extremely sharp interfaces; it will be necessary to verify the integrity of thin layers and layered structure devices over thicknesses comparable to the atomic layer spacing. Analytical techniques which probe the first 1--2 atomic layers are therefore necessary for in-situ characterization of relevant thin film growth processes. However, most surface-analytical techniques are sensitive to a region within 10--40 Angstrom of the surface and are physically incompatible with thin film deposition and are typically restricted to ultra high vacuum conditions. A review of ion beam-based analytical methods for the characterization of thin film and multi-layered thin film structures incorporating layers of multicomponent oxides is presented. Particular attention will be paid to the use of time-of-flight techniques based on the use of 1- 15 key ion beams which show potential for use as nondestructive, real-time, in-situ surface diagnostics for the growth of multicomponent metal and metal oxide thin films

  3. Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain.

    Science.gov (United States)

    Suzuki, Norihiro; Osada, Minoru; Billah, Motasim; Bando, Yoshio; Yamauchi, Yusuke; Hossain, Shahriar A

    2018-03-27

    Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

  4. Structural and magneto-dielectric property of (1-x)SBT-xLSMO nanocomposite thin films

    International Nuclear Information System (INIS)

    Maity, Sarmistha; Bhattacharya, D.; Dhar, A.; Ray, S.K.

    2009-01-01

    Full text: In recent years, interest in multiferroic materials has been increasing due to their potential applications. As single-phase multiferroic materials have very low room temperature magnetoelectric coefficient, recent studies have been concentrated on the possibility of attaining a coupling between the two order parameters by designing composites with magnetostrictive and piezoelectric phases via stress mediation. Composite thin films with homogenous matrix, composition spread with terminal layers being ferromagnetic and ferroelectric, layer-by-layer growth, superlattices, as well as epitaxial growth of ferromagnetic and ferroelectric layers on suitable substrates are been currently considered. In the present work, a nanostructured composite thin film of strontium bismuth tantalate (SBT) (ferroelectric layer) and lanthanum strontium manganese oxide (LSMO) (ferromagnetic layer) were fabricated using pulsed laser deposition. Phase separated multiferroic thin films with thickness varying from 50nm to 150nm were deposited from composite target (1-x)SBT-xLSMO with x=0.2, 0.5, 0.8. Grazing angle X-ray diffraction study combined with photo electron spectroscopy with depth profiling was carried out to study the phase separation. Interface quality of the thin film on silicon substrate was studied by Rutherford backscattering spectroscopy. Influence of film thickness and composition (x) on the electrical property of film was examined using impedance spectroscopy. The composite films exhibited ferroelectric as well as ferromagnetic characteristics at room temperature. A small kink in the dielectric spectra near the Neel temperature of LSMO confirmed the magneto-electric effect in the nanocomposite films

  5. Energy landscape scheme for an intuitive understanding of complex domain dynamics in ferroelectric thin films

    Science.gov (United States)

    Heon Kim, Tae; Yoon, Jong-Gul; Hyub Baek, Seung; Park, Woong-Kyu; Mo Yang, Sang; Yup Jang, Seung; Min, Taeyuun; Chung, Jin-Seok; Eom, Chang-Beom; Won Noh, Tae

    2015-07-01

    Fundamental understanding of domain dynamics in ferroic materials has been a longstanding issue because of its relevance to many systems and to the design of nanoscale domain-wall devices. Despite many theoretical and experimental studies, a full understanding of domain dynamics still remains incomplete, partly due to complex interactions between domain-walls and disorder. We report domain-shape-preserving deterministic domain-wall motion, which directly confirms microscopic return point memory, by observing domain-wall breathing motion in ferroelectric BiFeO3 thin film using stroboscopic piezoresponse force microscopy. Spatial energy landscape that provides new insights into domain dynamics is also mapped based on the breathing motion of domain walls. The evolution of complex domain structure can be understood by the process of occupying the lowest available energy states of polarization in the energy landscape which is determined by defect-induced internal fields. Our result highlights a pathway for the novel design of ferroelectric domain-wall devices through the engineering of energy landscape using defect-induced internal fields such as flexoelectric fields.

  6. Energy landscape scheme for an intuitive understanding of complex domain dynamics in ferroelectric thin films.

    Science.gov (United States)

    Kim, Tae Heon; Yoon, Jong-Gul; Baek, Seung Hyub; Park, Woong-kyu; Yang, Sang Mo; Yup Jang, Seung; Min, Taeyuun; Chung, Jin-Seok; Eom, Chang-Beom; Noh, Tae Won

    2015-07-01

    Fundamental understanding of domain dynamics in ferroic materials has been a longstanding issue because of its relevance to many systems and to the design of nanoscale domain-wall devices. Despite many theoretical and experimental studies, a full understanding of domain dynamics still remains incomplete, partly due to complex interactions between domain-walls and disorder. We report domain-shape-preserving deterministic domain-wall motion, which directly confirms microscopic return point memory, by observing domain-wall breathing motion in ferroelectric BiFeO3 thin film using stroboscopic piezoresponse force microscopy. Spatial energy landscape that provides new insights into domain dynamics is also mapped based on the breathing motion of domain walls. The evolution of complex domain structure can be understood by the process of occupying the lowest available energy states of polarization in the energy landscape which is determined by defect-induced internal fields. Our result highlights a pathway for the novel design of ferroelectric domain-wall devices through the engineering of energy landscape using defect-induced internal fields such as flexoelectric fields.

  7. Effects of doping on ferroelectric properties and leakage current behavior of KNN-LT-LS thin films on SrTiO3 substrate

    Science.gov (United States)

    Abazari, M.; Safari, A.

    2009-05-01

    We report the effects of Ba, Ti, and Mn dopants on ferroelectric polarization and leakage current of (K0.44Na0.52Li0.04)(Nb0.84Ta0.1Sb0.06)O3 (KNN-LT-LS) thin films deposited by pulsed laser deposition. It is shown that donor dopants such as Ba2+, which increased the resistivity in bulk KNN-LT-LS, had an opposite effect in the thin film. Ti4+ as an acceptor B-site dopant reduces the leakage current by an order of magnitude, while the polarization values showed a slight degradation. Mn4+, however, was found to effectively suppress the leakage current by over two orders of magnitude while enhancing the polarization, with 15 and 23 μC/cm2 remanent and saturated polarization, whose values are ˜70% and 82% of the reported values for bulk composition. This phenomenon has been associated with the dual effect of Mn4+ in KNN-LT-LS thin film, by substituting both A- and B-site cations. A detailed description on how each dopant affects the concentrations of vacancies in the lattice is presented. Mn-doped KNN-LT-LS thin films are shown to be a promising candidate for lead-free thin films and applications.

  8. Ferroelectric and piezoelectric responses of (110) and (001)-oriented epitaxial Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} thin films on all-oxide layers buffered silicon

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Hien Thu [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No.1 Dai Co Viet Road, Hanoi 10000 (Viet Nam); Nguyen, Minh Duc, E-mail: minh.nguyen@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No.1 Dai Co Viet Road, Hanoi 10000 (Viet Nam); Inorganic Materials Science (IMS), MESA + Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); SolMateS B.V., Drienerlolaan 5, Building 6, 7522 NB Enschede (Netherlands); Houwman, Evert; Boota, Muhammad [Inorganic Materials Science (IMS), MESA + Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Dekkers, Matthijn [SolMateS B.V., Drienerlolaan 5, Building 6, 7522 NB Enschede (Netherlands); Vu, Hung Ngoc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No.1 Dai Co Viet Road, Hanoi 10000 (Viet Nam); Rijnders, Guus [Inorganic Materials Science (IMS), MESA + Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2015-12-15

    Graphical abstract: The cross sections show a very dense structure in the (001)-oriented films (c,d), while an open columnar growth structure is observed in the case of the (110)-oriented films (a,b). The (110)-oriented PZT films show a significantly larger longitudinal piezoelectric coefficient (d33{sub ,f}), but smaller transverse piezoelectric coefficient (d31{sub ,f}) than the (001) oriented films. - Highlights: • We fabricate all-oxide, epitaxial piezoelectric PZT thin films on Si. • The orientation of the films can be controlled by changing the buffer layer stack. • The coherence of the in-plane orientation of the grains and grain boundaries affects the ferroelectric properties. • Good cycling stability of the ferroelectric properties of (001)-oriented PZT thin films. The (110)-oriented PZT thin films show a larger d33{sub ,f} but smaller d31{sub ,f} than the (001)-oriented films. - Abstract: Epitaxial ferroelectric Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) thin films were fabricated on silicon substrates using pulsed laser deposition. Depending on the buffer layers and perovskite oxide electrodes, epitaxial films with different orientations were grown. (110)-oriented PZT/SrRuO{sub 3} (and PZT/LaNiO{sub 3}) films were obtained on YSZ-buffered Si substrates, while (001)-oriented PZT/SrRuO{sub 3} (and PZT/LaNiO{sub 3}) were fabricated with an extra CeO{sub 2} buffer layer (CeO{sub 2}/YSZ/Si). There is no effect of the electrode material on the properties of the films. The initial remnant polarizations in the (001)-oriented films are higher than those of (110)-oriented films, but it increases to the value of the (001) films upon cycling. The longitudinal piezoelectric d33{sub ,f} coefficients of the (110) films are larger than those of the (001) films, whereas the transverse piezoelectric d31{sub ,f} coefficients in the (110)-films are less than those in the (001)-oriented films. The difference is ascribed to the lower density (connectivity between

  9. Influence of plasma pressure on the growth characteristics and ferroelectric properties of sputter-deposited PZT thin films

    International Nuclear Information System (INIS)

    Bose, A.; Maity, T.; Bysakh, S.; Seal, A.; Sen, Suchitra

    2010-01-01

    PZT thin films of thickness (320-1040) nm were synthesized on Si/SiO 2 /Ti/Pt multilayered substrates by radio frequency magnetron sputtering. The influence of plasma pressure in the range of (0.24-4.9) Pa, during deposition, on the structural, electrical and ferroelectric properties of the PZT films was systematically studied. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and cross-sectional transmission electron microscopy (XTEM) were employed for structural study. Nano-probe Energy Dispersive (EDX) line scanning was employed to investigate the elemental distribution across the film-bottom electrode interface. I-V characteristics and polarization-electric field (P-E) hysteresis loop of the films were measured. The study reveals that the plasma pressure has a strong influence on the evolution and texture of the ferroelectric perovskite phase and microstructure of the films. At an optimum plasma pressure of 4.1 Pa, PZT films are grown with 93% perovskite phase with (1 1 1) preferred orientation and uniform granular microstructure. These films show a saturation polarization of 67 μC/cm 2 , remnant polarization of 30 μC/cm 2 and coercive field of 28 kV/cm which, according to the literature, seem to be suitable for device applications. Transmission electron microscopy (TEM) study shows that at a plasma pressure of 4.1 Pa, the PZT/bottom Pt interface is sharp and no amorphous interlayer is formed at the interface. At a higher plasma pressure of 4.9 Pa, poor I-V and P-E hysteresis loop are observed which are interpreted as due to an amorphous interlayer at the film-bottom electrode interface which is possibly enriched in Pb, Zr, O and Pt.

  10. Ferroelectric properties of barium strontium titanate thin films grown by RF co-sputtering

    International Nuclear Information System (INIS)

    Zapata-Navarro, A.; Marquez-Herrera, A.; Cruz-Jauregui, M.P.; Calzada, M.L.

    2005-01-01

    In this work, we present the variation of the ferroelectric properties of Ba 1-x Sr x TiO 3 films deposited on Pt/TiO 2 /SiO 2 /Si substrates by RF co-sputtering with 0≤x≤1. The co-sputtering was done using a single magnetron with BaTiO 3 /SrTiO 3 targets in a pie mosaics configuration. Smooth and uniform films were obtained using the same conditions of growth and annealing temperature. The X-ray diffraction and EDS results show that the processes were managed to obtain crystalline materials with x from 0 to 1. The behaviour of P-E loops suggests that the ferroelectric properties of the films were tuned by changing the concentration of the cation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. A thermally robust and thickness independent ferroelectric phase in laminated hafnium zirconium oxide

    Directory of Open Access Journals (Sweden)

    S. Riedel

    2016-09-01

    Full Text Available Ferroelectric properties in hafnium oxide based thin films have recovered the scaling potential for ferroelectric memories due to their ultra-thin-film- and CMOS-compatibility. However, the variety of physical phenomena connected to ferroelectricity allows a wider range of applications for these materials than ferroelectric memory. Especially mixed HfxZr1-xO2 thin films exhibit a broad compositional range of ferroelectric phase stability and provide the possibility to tailor material properties for multiple applications. Here it is shown that the limited thermal stability and thick-film capability of HfxZr1-xO2 can be overcome by a laminated approach using alumina interlayers.

  12. Growth of KNN thin films for non-linear optical applications

    International Nuclear Information System (INIS)

    Sharma, Shweta; Gupta, Reema; Gupta, Vinay; Tomar, Monika

    2018-01-01

    Two-wave mixing is a remarkable area of research in the field of non-linear optics, finding various applications in the development of opto-electronic devices, photorefractive waveguides, real time holography, etc. Non-linear optical properties of ferroelectric potassium sodium niobate (KNN) thin films have been interrogated using two-wave mixing phenomenon. Regarding this, a-axis oriented K 0.35 Na (1-0.35) NbO 3 thin films were successfully grown on epitaxial matched (100) SrTiO 3 substrate using pulsed laser deposition (PLD) technique. The uniformly distributed Au micro-discs of 200 μm diameter were integrated with KNN/STO thin film to study the plasmonic enhancement in the optical response. Beam amplification has been observed as a result of the two-wave mixing. This is due to the alignment of ferroelectric domains in KNN films and the excitement of plasmons at the metal-dielectric (Au-KNN) interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Growth of KNN thin films for non-linear optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Shweta; Gupta, Reema; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi (India); Tomar, Monika [Department of Physics, Miranda House University of Delhi (India)

    2018-02-15

    Two-wave mixing is a remarkable area of research in the field of non-linear optics, finding various applications in the development of opto-electronic devices, photorefractive waveguides, real time holography, etc. Non-linear optical properties of ferroelectric potassium sodium niobate (KNN) thin films have been interrogated using two-wave mixing phenomenon. Regarding this, a-axis oriented K{sub 0.35}Na{sub (1-0.35)}NbO{sub 3} thin films were successfully grown on epitaxial matched (100) SrTiO{sub 3} substrate using pulsed laser deposition (PLD) technique. The uniformly distributed Au micro-discs of 200 μm diameter were integrated with KNN/STO thin film to study the plasmonic enhancement in the optical response. Beam amplification has been observed as a result of the two-wave mixing. This is due to the alignment of ferroelectric domains in KNN films and the excitement of plasmons at the metal-dielectric (Au-KNN) interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Tunable strain effect and ferroelectric field effect on the electronic transport properties of La0.5Sr0.5CoO3 thin films

    Science.gov (United States)

    Zhu, Q. X.; Wang, W.; Zhao, X. Q.; Li, X. M.; Wang, Y.; Luo, H. S.; Chan, H. L. W.; Zheng, R. K.

    2012-05-01

    Tensiled La0.5Sr0.5CoO3 (LSCO) thin films were epitaxially grown on piezoelectric 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) single-crystal substrates. Due to the epitaxial nature of the interface, the lattice strain induced by ferroelectric poling or the converse piezoelectric effect in the PMN-PT substrate is effectively transferred to the LSCO film and thus reduces the tensile strain of the film, giving rise to a decrease in the resistivity of the LSCO film. We discuss these strain effects within the framework of the spin state transition of Co3+ ions and modification of the electronic bandwidth that is relevant to the induced strain. By simultaneously measuring the strain and the resistivity, quantitative relationship between the resistivity and the strain was established for the LSCO film. Both theoretical calculation and experimental results demonstrate that the ferroelectric field effect at room temperature in the LSCO/PMN-PT field-effect transistor is minor and could be neglected. Nevertheless, with decreasing temperature, the ferroelectric field effect competes with the strain effect and plays a more and more important role in influencing the electronic transport properties of the LSCO film, which we interpreted as due to the localization of charge carriers at low temperature.

  15. Intelligent Processing of Ferroelectric Thin Films

    Science.gov (United States)

    1994-05-31

    unsatisfactory. To detect the electroopic effects of thin films deposited on opaque substrates a waveguide refractometry of category 3 was reported. An advantage...of the waveguide refractometry is its capability of resolving the change in ordinary index from the change in the extraordinary index. Some successes

  16. Research and development on university-collaboration type industrial and scientific technologies in fiscal 1999. Achievement report on research and development of the next generation ferroelectric thin film memory (research and development of the next generation ferroelectric memory); 1999 nendo jisedai kyoyudentai memory no kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    With an objective to realize the next generation ferroelectric memory, research and development has been carried out on quality improvement in ferroelectric thin films. This paper summarizes the achievements in fiscal 1999. In the search and research on new ferroelectric materials, discussions were given on such new materials as Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} in addition to the conventional PLZT and SBT. In the research on film forming processes, the sol-gel method, the organic metal gaseous phase growth method and the sputtering method were used. In improving the quality of buffer layers, research was performed to use as a buffer layer the STA/SiON laminated structure in which silicon substrates were nitrided, and a film of SrTa{sub 2}O{sub 6} (STA) being a high ferroelectric material was formed. As a result of the research, a buffer layer having thin films with thickness of 3.7 to 4.8 nm as converted to SiO{sub 2} was obtained, wherein a leak current smaller than the tunnel current of the SiO{sub 2} film having the same thickness was shown. In the search for materials and research on film forming technologies to develop function separated type memory, such pure metals as Pt, Ir and Ru and their conductive oxides were used to evaluate properties as a floating gate electrode. (NEDO)

  17. Optical and electro-optic anisotropy of epitaxial PZT thin films

    Science.gov (United States)

    Zhu, Minmin; Du, Zehui; Jing, Lin; Yoong Tok, Alfred Iing; Tong Teo, Edwin Hang

    2015-07-01

    Strong optical and electro-optic (EO) anisotropy has been investigated in ferroelectric Pb(Zr0.48Ti0.52)O3 thin films epitaxially grown on Nb-SrTiO3 (001), (011), and (111) substrates using magnetron sputtering. The refractive index, electro-optic, and ferroelectric properties of the samples demonstrate the significant dependence on the growth orientation. The linear electro-optic coefficients of the (001), (011), and (111)-oriented PZT thin films were 270.8, 198.8, and 125.7 pm/V, respectively. Such remarkable anisotropic EO behaviors have been explained according to the structure correlation between the orientation dependent distribution, spontaneous polarization, epitaxial strain, and domain pattern.

  18. Ferroelectric properties of barium strontium titanate thin films grown by RF co-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Navarro, A.; Marquez-Herrera, A. [CICATA-IPN, Km. 14.5 Carretera Tampico-Puerto Ind. Altamira, Altamira Tamaulipas 89600 (Mexico); Cruz-Jauregui, M.P. [CCMC-UNAM, Km. 107 Carretera Tijuana-Ensenada, Ensenada B.C. 22800 (Mexico); Calzada, M.L. [ICMM (CSIC) Madrid, Cantoblanco Madrid 28049 (Spain)

    2005-08-01

    In this work, we present the variation of the ferroelectric properties of Ba{sub 1-x}Sr{sub x}TiO{sub 3} films deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates by RF co-sputtering with 0{<=}x{<=}1. The co-sputtering was done using a single magnetron with BaTiO{sub 3}/SrTiO{sub 3} targets in a pie mosaics configuration. Smooth and uniform films were obtained using the same conditions of growth and annealing temperature. The X-ray diffraction and EDS results show that the processes were managed to obtain crystalline materials with x from 0 to 1. The behaviour of P-E loops suggests that the ferroelectric properties of the films were tuned by changing the concentration of the cation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Investigation of the ferroelectric switching behavior of P(VDF-TrFE)-PMMA blended films for synaptic device applications

    International Nuclear Information System (INIS)

    Kim, E J; Kim, K A; Yoon, S M

    2016-01-01

    Synaptic plasticity can be mimicked by electronic synaptic devices. By using ferroelectric thin films as gate insulator for thin-film transistors (TFT), channel conductance can be defined as the synaptic plasticity, and gradually modulated by the variations in amounts of aligned ferroelectric dipoles. Poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)]-poly(methyl methacrylate) (PMMA) blended films are chosen and their switching kinetics are investigated by using the Kolmogorov-Avrami-Ishibashi model. The switching time for ferroelectric polarization is sensitively influenced by the amplitude of applied electric field and volumetric ratio of ferroelectric beta-phases in the P(VDF-TrFE)-PMMA films. The switching time of the P(VDF-TrFE) increases with decreasing the pulse amplitude and/or the ratio of ferroelectric beta-phases by incorporation of PMMA. The activation electric field is also found to increase as the increase in blended amount of PMMA. Synapse TFTs are fabricated using the P(VDF-TrFE)-PMMA as gate insulator and In-Ga-Zn-O active channels. The drain currents of the synapse TFTs gradually increased when the voltage pulse signals with given duration are repeatedly applied. This suggests that the synaptic weights can be modulated by the number of external pulse signals, and that the proposed synapse TFT can be applied for mimicking the operations of bio-synapses. (paper)

  20. Proceedings of the international conference on thin films and applications: book of abstracts

    International Nuclear Information System (INIS)

    2013-01-01

    In the era of miniaturization, the role of thin films is highly significant to achieve smaller devices with higher speed especially in new generation of integrated circuits, sensors, flat panel displays, Micro-Electro-Mechanical Systems (MEMS), biomedical devices, optical instruments and microwave communications. Thin films as a nano-scale dimensional system have great importance to many challenging applications. Biological coatings, clean energy, ferroelectric and piezoelectric thin films, ion beam thin films, magnetic thin films, nanostructured and nano composite coatings, NEMS, sensors, thin film preparation and characterization are the topics covered in this symposium. Papers relevant to INIS are indexed separately

  1. Ferroelectricity down to at least 2 nm in multiferroic BiFeO3 epitaxial thin films

    International Nuclear Information System (INIS)

    Bea, H.; Fusil, S.; Bouzehouane, K.; Sirena, M.; Herranz, G.; Jacquet, E.; Contour, J.-P.; Barthelemy, A.; Bibes, M.

    2006-01-01

    We report here on the preservation of ferroelectricity down to 2 nm in BiFeO 3 ultrathin films. The electric polarization can be switched reversibly and is stable over several days. Our findings insight on the fundamental problem of ferroelectricity at low thickness and confirm the potential of BiFeO 3 as a lead-free ferroelectric and multiferroic material for nanoscale devices. (author)

  2. Suppression of slow capacitance relaxation phenomenon in Pt/Ba0.3Sr0.7TiO3/Pt thin film ferroelectric structures by annealing in oxygen atmosphere

    KAUST Repository

    Altynnikov, A. G.; Gagarin, A. G.; Gaidukov, M. M.; Tumarkin, A. V.; Petrov, P. K.; Alford, N.; Kozyrev, A. B.

    2014-01-01

    The impact of oxygen annealing on the switching time of ferroelectric thin film capacitor structures Pt/Ba0.3Sr0.7TiO3/Pt was investigated. The response of their capacitance on pulsed control voltages before and after annealing was experimentally

  3. Ferroelectric domain inversion and its stability in lithium niobate thin film on insulator with different thicknesses

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Guang-hao; Bai, Yu-hang; Cui, Guo-xin; Li, Chen; Qiu, Xiang-biao; Wu, Di; Lu, Yan-qing, E-mail: yqlu@nju.edu.cn [National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Geng, De-qiang [Jinan Jingzheng Electronics Co., Ltd., Jinan 250100 (China)

    2016-07-15

    Ferroelectric domain inversion and its effect on the stability of lithium niobate thin films on insulator (LNOI) are experimentally characterized. Two sets of specimens with different thicknesses varying from submicron to microns are selected. For micron thick samples (∼28 μm), domain structures are achieved by pulsed electric field poling with electrodes patterned via photolithography. No domain structure deterioration has been observed for a month as inspected using polarizing optical microscopy and etching. As for submicron (540 nm) films, large-area domain inversion is realized by scanning a biased conductive tip in a piezoelectric force microscope. A graphic processing method is taken to evaluate the domain retention. A domain life time of 25.0 h is obtained and possible mechanisms are discussed. Our study gives a direct reference for domain structure-related applications of LNOI, including guiding wave nonlinear frequency conversion, nonlinear wavefront tailoring, electro-optic modulation, and piezoelectric devices.

  4. Pr and Gd co-doped bismuth ferrite thin films with enhanced ...

    Indian Academy of Sciences (India)

    in Pr content, the crystal structures of BPGFO thin films retain rhombohedral (R3c) symmetry accompanied by structure distortion. ... Pr and Gd co-modified BiFeO3 thin film; ferroelectric properties; sol-gel. 1. Introduction. In recent years, great attention has been paid to single- phase BiFeO3 (BFO) multiferroic materials ...

  5. Ferroelectric properties of BaTiO3/PbZr0.2Ti.08O3 bilayer thin film

    Science.gov (United States)

    Salev, Pavel; Yang, Chun; Grigoriev, Alexei

    2014-03-01

    The thin film ferroelectric BaTiO3/PbZr0.2Ti0.8O3 bilayer was epitaxially grown on SrRuO3/SrTiO3 substrate by RF sputtering. Electrical measurements of polarization switching revealed two different switching regimes - a small ferroelectric hysteresis loop at low applied voltage and a larger loop at a high voltage. The measured dielectric permittivity corresponds to weak electrostatic coupling between two layers according to Landau-Ginsburg-Devonshire theory. This weak coupling may allow for independent polarization states to exist in individual layers. This can lead to stable head-to-head and tail-to-tail polarization domain configurations, which would explain the two switching regimes observed in electrical measurements. The compensation of polarization gradient across the interface can be explained by the enhancement of interface charge carrier density due to strong bending of electron energy bands. This work was supported by NSF award DMR-1057159.

  6. Dynamics of ferroelectric nanodomains in BaTiO3 epitaxial thin films via piezoresponse force microscopy

    International Nuclear Information System (INIS)

    Pertsev, N A; Petraru, A; Kohlstedt, H; Waser, R; Bdikin, I K; Kiselev, D; Kholkin, A L

    2008-01-01

    Ferroelectric nanodomains were created in BaTiO 3 thin films by applying a voltage to a sharp conducting tip of a scanning force microscope (SFM). The films were epitaxially grown on SrRuO 3 -covered (001)-oriented SrTiO 3 substrates by a high-pressure sputtering. They appeared to be single-crystalline with the (001) crystallographic orientation relative to the substrate. Using the piezoresponse mode of the SFM to detect the out-of-plane film polarization, the domain sizes were measured as a function of the applied writing voltage and the pulse time. It was found that the time dependence of the domain diameter in a 60 nm thick BaTiO 3 film deviates significantly from the logarithmic law observed earlier in Pb(Zr 0.2 Ti 0.8 )O 3 (PZT) films. At a given writing time, the domain size increases nonlinearly with increasing applied voltage, in contrast to the linear behavior reported earlier for PZT films and LiNbO 3 single crystals. The dynamics of domain growth is analyzed theoretically taking into account the strong inhomogeneity of the external electric field in the film and the influence of the bottom electrode. It is shown that the observed writing time and voltage dependences of the domain size can be explained by the domain-wall creep in the presence of random-bond disorder

  7. Preparation and properties of the (Sr,BaNb2O6 thin films by using the sputtering method

    Directory of Open Access Journals (Sweden)

    Diao Chien-Chen

    2017-01-01

    Full Text Available Strontium barium niobate (Sr0.3Ba0.7Nb2O6, SBN thin films were deposited on silicon substrate by using the radio frequency magnetron sputtering and under different deposition power and time at room temperature. Surface morphology and thicknesses of the SBN thin films were characterized by field emission scanning electron microscopy. The crystallization films at different deposition power and time were analyzed by X-ray diffraction (XRD using CuKα radiation from a Rigaku rotating anode with an incident angle of 2°. The remnant polarization (Pr, saturation polarization (Ps, and minimum coercive field (Ec properties of the metal-ferroelectric-metal (MFM structure were measured using ferroelectric material test instrument. The SBN thin films deposited at 90 min and 125 W had the maximum Pr, Ps, and minimum Ec of 1.26 μC/cm2, 2.41 μC/cm2, and 201.6 kV/cm, respectively. From above results, it knows that the SBN thin films suit for application on ferroelectric random access memory (FeRAM.

  8. Nonlinear dielectric response in ferroelectric thin films

    Directory of Open Access Journals (Sweden)

    Lente, M. H.

    2004-08-01

    Full Text Available Electrical permittivity dependence on electric external bias field was investigated in PZT thin films. The results revealed the existence of two mechanisms contributing to the electrical permittivity. The first one was related to the domain reorientation, which was responsible for a strong no linear dielectric behavior, acting only during the poling process. The second mechanism was associated with the domain wall vibrations, which presented a reasonable linear electrical behavior with the applied bias field, contributing always to the permittivity independently of the poling state of the sample. The results also indicated that the gradual reduction of the permittivity with the increase of the bias field strength may be related to the gradual bending of the domain walls. It is believed that the domain wall bending induces a hardening and/or a thinning of the walls, thus reducing the electrical permittivity. A reinterpretation of the model proposed in the literature to explain the dielectric characteristics of ferroelectric materials at high electric field regime is proposed.

    Se ha estudiado la dependencia de la permitividad eléctrica con un campo bias externo en láminas delgadas de PZT. Los resultados revelaron la existencia de dos mecanismos que contribuyen a la permitividad eléctrica. El primero está relacionado con la reorientación de dominios, actúa sólo durante el proceso de polarización y es responsable de un comportamiento dieléctrico fuertemente no lineal. El segundo mecanismo se asocia a las vibraciones de las paredes de dominio, presentando un comportamiento eléctrico razonablemente lineal con el campo bias aplicado, contribuyendo siempre a la permitividad independientemente del estado de polarización de la muestra. Los resultados indicaron también que la reducción gradual de la permitividad con el aumento de la fuerza del campo bias podría estar relacionada con el “bending” gradual de las paredes de dominio

  9. Misfit strain-film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Q.Y.; Mahjoub, R. [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Alpay, S.P. [Materials Science and Engineering Program and Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Nagarajan, V., E-mail: nagarajan@unsw.edu.au [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2010-02-15

    The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr{sub 1-x}Ti{sub x}O{sub 3} (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau-Ginzburg-Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric-ferroelectric phase transformation temperature. Film thickness-misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities {epsilon}{sub 11} and {epsilon}{sub 33}, as well as the out-of-plane piezoelectric coefficients d{sub 33} for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization.

  10. Improving information density in ferroelectric polymer films by using nanoimprinted gratings

    Science.gov (United States)

    Martínez-Tong, Daniel E.; Soccio, Michela; Rueda, Daniel R.; Nogales, Aurora; García-Gutiérrez, Mari Cruz; Ezquerra, Tiberio A.

    2015-03-01

    The development of polymer non-volatile memories depends on the effective fabrication of devices with high density of information. Well-defined low aspect ratio nanogratings on thin films of poly(vinylidene fluoride-trifluoroethylene) copolymers can be fabricated by using Nanoimprint Lithography (NIL). By using these nanogratings, an improved management of writing and reading information can be reached as revealed by Piezoresponse Force Microscopy (PFM). Structural investigation by means of Grazing Incidence X-ray (GIX) scattering techniques indicates that the physical confinement generated by nanoimprint promotes the development of smaller and edge-on oriented crystals. Our results evidence that one-dimensional nanostructuring can be a straightforward approach to improve the control of the polarization in ferroelectric polymer thin films.

  11. Thermal stability of pulsed laser deposited iridium oxide thin films at low oxygen atmosphere

    Science.gov (United States)

    Gong, Yansheng; Wang, Chuanbin; Shen, Qiang; Zhang, Lianmeng

    2013-11-01

    Iridium oxide (IrO2) thin films have been regarded as a leading candidate for bottom electrode and diffusion barrier of ferroelectric capacitors, some process related issues need to be considered before integrating ferroelectric capacitors into memory cells. This paper presents the thermal stability of pulsed laser deposited IrO2 thin films at low oxygen atmosphere. Emphasis was given on the effect of post-deposition annealing temperature at different oxygen pressure (PO2) on the crystal structure, surface morphology, electrical resistivity, carrier concentration and mobility of IrO2 thin films. The results showed that the thermal stability of IrO2 thin films was strongly dependent on the oxygen pressure and annealing temperature. IrO2 thin films can stably exist below 923 K at PO2 = 1 Pa, which had a higher stability than the previous reported results. The surface morphology of IrO2 thin films depended on PO2 and annealing temperature, showing a flat and uniform surface for the annealed films. Electrical properties were found to be sensitive to both the annealing temperature and oxygen pressure. The room-temperature resistivity of IrO2 thin films with a value of 49-58 μΩ cm increased with annealing temperature at PO2 = 1 Pa. The thermal stability of IrO2 thin films as a function of oxygen pressure and annealing temperature was almost consistent with thermodynamic calculation.

  12. Formation of (111) orientation-controlled ferroelectric orthorhombic HfO{sub 2} thin films from solid phase via annealing

    Energy Technology Data Exchange (ETDEWEB)

    Mimura, Takanori; Katayama, Kiliha [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Yokohama 226-8502 (Japan); Shimizu, Takao [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Uchida, Hiroshi [Department of Materials and Life Sciences, Sophia University, Tokyo 102-8554 (Japan); Kiguchi, Takanori; Akama, Akihiro; Konno, Toyohiko J. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Sakata, Osami [Synchrotron X-ray Station at SPring-8 and Synchrotron X-ray Group, National Institute for Materials Science, Sayo, Hyogo 679-5148 (Japan); Funakubo, Hiroshi, E-mail: funakubo.h.aa@m.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Yokohama 226-8502 (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama 226-8502 (Japan)

    2016-08-01

    0.07YO{sub 1.5}-0.93HfO{sub 2} (YHO7) films were prepared on various substrates by pulse laser deposition at room temperature and subsequent heat treatment to enable a solid phase reaction. (111)-oriented 10 wt. % Sn-doped In{sub 2}O{sub 3}(ITO)//(111) yttria-stabilized zirconia, (111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si substrates, and (111)ITO/(111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si substrates were employed for film growth. In this study, X-ray diffraction measurements including θ–2θ measurements, reciprocal space mappings, and pole figure measurements were used to study the films. The film on (111)ITO//(111)yttria-stabilized zirconia was an (111)-orientated epitaxial film with ferroelectric orthorhombic phase; the film on (111)ITO/(111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si was an (111)-oriented uniaxial textured film with ferroelectric orthorhombic phase; and no preferred orientation was observed for the film on the (111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si substrate, which does not contain ITO. Polarization–hysteresis measurements confirmed that the films on ITO covered substrates had saturated ferroelectric hysteresis loops. A remanent polarization (P{sub r}) of 9.6 and 10.8 μC/cm{sup 2} and coercive fields (E{sub c}) of 1.9 and 2.0 MV/cm were obtained for the (111)-oriented epitaxial and uniaxial textured YHO7 films, respectively. These results demonstrate that the (111)-oriented ITO bottom electrodes play a key role in controlling the orientation and ferroelectricity of the phase formation of the solid films deposited at room temperature.

  13. Polarization retention loss in PbTiO3 ferroelectric films due to leakage currents

    NARCIS (Netherlands)

    Morelli, A.; Venkatesan, Sriram; Palasantzas, G.; Kooi, B. J.; De Hosson, J. Th. M.

    2007-01-01

    The relationship between retention loss in single crystal PbTiO3 ferroelectric thin films and leakage currents is demonstrated by piezoresponse and conductive atomic force microscopy measurements. It was found that the polarization reversal in the absence of an electric field followed a stretched

  14. Elaboration of strontium ruthenium oxide thin films on metal substrates by chemical solution deposition

    International Nuclear Information System (INIS)

    Seveno, R.; Braud, A.; Gundel, H.W.

    2005-01-01

    In order to improve the structural interface between a metal substrate and a lead zirconate titanate (Pb(ZrTi)O 3 , PZT) ferroelectric thin film, the elaboration of strontium ruthenium oxide (SrRuO 3 ) by chemical solution deposition is studied. The SrRuO 3 thin films were realized by multiple spin-coating technique and the temperature of the rapid thermal annealing process was optimized. The crystallization behavior was examined by X-ray diffraction; surface analyses using scanning electron microscope and atomic force microscope techniques showed the influence of the SrRuO 3 layer at the interface PZT/metal on the morphology of the ferroelectric thin film. From the electrical measurements, a coercive electric field around 25 kV/cm and a remanent polarization of approximately 30 μC/cm were found

  15. Elastic recoil detection analysis of ferroelectric films

    Energy Technology Data Exchange (ETDEWEB)

    Stannard, W.B.; Johnston, P.N.; Walker, S.R.; Bubb, I.F. [Royal Melbourne Inst. of Tech., VIC (Australia); Scott, J.F. [New South Wales Univ., Kensington, NSW (Australia); Cohen, D.D.; Dytlewski, N. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    There has been considerable progress in developing SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub O.7}Sr{sub O.3}TiO{sub 3} (BST) ferroelectric films for use as nonvolatile memory chips and for capacitors in dynamic random access memories (DRAMs). Ferroelectric materials have a very large dielectric constant ( {approx} 1000), approximately one hundred times greater than that of silicon dioxide. Devices made from these materials have been known to experience breakdown after a repeated voltage pulsing. It has been suggested that this is related to stoichiometric changes within the material. To accurately characterise these materials Elastic Recoil Detection Analysis (ERDA) is being developed. This technique employs a high energy heavy ion beam to eject nuclei from the target and uses a time of flight and energy dispersive (ToF-E) detector telescope to detect these nuclei. The recoil nuclei carry both energy and mass information which enables the determination of separate energy spectra for individual elements or for small groups of elements In this work ERDA employing 77 MeV {sup 127}I ions has been used to analyse Strontium Bismuth Tantalate thin films at the heavy ion recoil facility at ANSTO, Lucas Heights. 9 refs., 5 figs.

  16. Elastic recoil detection analysis of ferroelectric films

    Energy Technology Data Exchange (ETDEWEB)

    Stannard, W B; Johnston, P N; Walker, S R; Bubb, I F [Royal Melbourne Inst. of Tech., VIC (Australia); Scott, J F [New South Wales Univ., Kensington, NSW (Australia); Cohen, D D; Dytlewski, N [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1997-12-31

    There has been considerable progress in developing SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub O.7}Sr{sub O.3}TiO{sub 3} (BST) ferroelectric films for use as nonvolatile memory chips and for capacitors in dynamic random access memories (DRAMs). Ferroelectric materials have a very large dielectric constant ( {approx} 1000), approximately one hundred times greater than that of silicon dioxide. Devices made from these materials have been known to experience breakdown after a repeated voltage pulsing. It has been suggested that this is related to stoichiometric changes within the material. To accurately characterise these materials Elastic Recoil Detection Analysis (ERDA) is being developed. This technique employs a high energy heavy ion beam to eject nuclei from the target and uses a time of flight and energy dispersive (ToF-E) detector telescope to detect these nuclei. The recoil nuclei carry both energy and mass information which enables the determination of separate energy spectra for individual elements or for small groups of elements In this work ERDA employing 77 MeV {sup 127}I ions has been used to analyse Strontium Bismuth Tantalate thin films at the heavy ion recoil facility at ANSTO, Lucas Heights. 9 refs., 5 figs.

  17. Surface-screening mechanisms in ferroelectric thin films and their effect on polarization dynamics and domain structures

    Energy Technology Data Exchange (ETDEWEB)

    Kalinin, Sergei V.; Kim, Yunseok; Fong, Dillon D.; Morozovska, Anna N.

    2018-01-25

    For over 70 years, ferroelectric materials have been one of the central research topics for condensed matter physics and material science, an interest driven both by fundamental science and applications. However, ferroelectric surfaces, the key component of ferroelectric films and nanostructures, still present a significant theoretical and even conceptual challenge. Indeed, stability of ferroelectric phase per se necessitates screening of polarization charge. At surfaces, this can lead to coupling between ferroelectric and semiconducting properties of material, or with surface (electro) chemistry, going well beyond classical models applicable for ferroelectric interfaces. In this review, we summarize recent studies of surface-screening phenomena in ferroelectrics. We provide a brief overview of the historical understanding of the physics of ferroelectric surfaces, and existing theoretical models that both introduce screening mechanisms and explore the relationship between screening and relevant aspects of ferroelectric functionalities starting from phase stability itself. Given that the majority of ferroelectrics exist in multiple-domain states, we focus on local studies of screening phenomena using scanning probe microscopy techniques. We discuss recent studies of static and dynamic phenomena on ferroelectric surfaces, as well as phenomena observed under lateral transport, light, chemical, and pressure stimuli. We also note that the need for ionic screening renders polarization switching a coupled physical-electrochemical process and discuss the non-trivial phenomena such as chaotic behavior during domain switching that stem from this.

  18. Surface-screening mechanisms in ferroelectric thin films and their effect on polarization dynamics and domain structures

    Science.gov (United States)

    Kalinin, Sergei V.; Kim, Yunseok; Fong, Dillon D.; Morozovska, Anna N.

    2018-03-01

    For over 70 years, ferroelectric materials have been one of the central research topics for condensed matter physics and material science, an interest driven both by fundamental science and applications. However, ferroelectric surfaces, the key component of ferroelectric films and nanostructures, still present a significant theoretical and even conceptual challenge. Indeed, stability of ferroelectric phase per se necessitates screening of polarization charge. At surfaces, this can lead to coupling between ferroelectric and semiconducting properties of material, or with surface (electro) chemistry, going well beyond classical models applicable for ferroelectric interfaces. In this review, we summarize recent studies of surface-screening phenomena in ferroelectrics. We provide a brief overview of the historical understanding of the physics of ferroelectric surfaces, and existing theoretical models that both introduce screening mechanisms and explore the relationship between screening and relevant aspects of ferroelectric functionalities starting from phase stability itself. Given that the majority of ferroelectrics exist in multiple-domain states, we focus on local studies of screening phenomena using scanning probe microscopy techniques. We discuss recent studies of static and dynamic phenomena on ferroelectric surfaces, as well as phenomena observed under lateral transport, light, chemical, and pressure stimuli. We also note that the need for ionic screening renders polarization switching a coupled physical–electrochemical process and discuss the non-trivial phenomena such as chaotic behavior during domain switching that stem from this. ).

  19. Effects of Bi doping on dielectric and ferroelectric properties

    Indian Academy of Sciences (India)

    [Pb0.95(La1−Bi)0.05][Zr0.53Ti0.47]O3 (PLBZT) ferroelectric thin films have been synthesized on indium tin oxide (ITO)-coated glass by sol–gel processing. PLBZT thin films were annealed at a relatively low temperature of 550 °C in oxygen ambient. Effects of Bi doping on structure, dielectric and ferroelectric properties of ...

  20. Research Update: Enhanced energy storage density and energy efficiency of epitaxial Pb0.9La0.1(Zr0.52Ti0.48O3 relaxor-ferroelectric thin-films deposited on silicon by pulsed laser deposition

    Directory of Open Access Journals (Sweden)

    Minh D. Nguyen

    2016-08-01

    Full Text Available Pb0.9La0.1(Zr0.52Ti0.48O3 (PLZT relaxor-ferroelectric thin films were grown on SrRuO3/SrTiO3/Si substrates by pulsed laser deposition. A large recoverable storage density (Ureco of 13.7 J/cm3 together with a high energy efficiency (η of 88.2% under an applied electric field of 1000 kV/cm and at 1 kHz frequency was obtained in 300-nm-thick epitaxial PLZT thin films. These high values are due to the slim and asymmetric hysteresis loop when compared to the values in the reference undoped epitaxial lead zirconate titanate Pb(Zr0.52Ti0.48O3 ferroelectric thin films (Ureco = 9.2 J/cm3 and η = 56.4% which have a high remanent polarization and a small shift in the hysteresis loop, under the same electric field.

  1. Photoinduced effects of ferroelectric domains in PbZr1-xTixO3 thin films as obtained by using piezoresponse force microscopy

    International Nuclear Information System (INIS)

    Jang, Y. H.; Kim, C. H.; Hwang, H. J.; Cho, J. H.; Moon, H. B.; Bhang, S. H.

    2011-01-01

    Piezoresponse force microscopy (PFM) has been used to investigate the photoinduced effect of ferroelectric domains in PbZr 1-x Ti x O 3 (PZT) thin films. In order to perform nondestructive visualization of the high-resolution domain structure, we optimized the imaging condition, such as applying a lower voltage than 1.0 Vpp (peak-to-peak voltage). In this study, domain changes were measured before and after illumination on the surface of PZT films by using an UV light emitting diode (LED) source (λ = 310 nm) with a focusing lens to investigate the influence of the photoinduced carriers on the ferroelectric polarization. In addition, to investigate the photoinduced effects on the domain distribution, we performed histogram of positive and negative domains before and after UV-light illumination. The illumination with UV light resulted in an increase of the positive domain of the out-of-plane mode. Also, a change in the out-of-plane domain distribution was observed before and after UV illumination. The relaxation of photoinduced changes was monitored by repeated scans within a time range of 20 ∼ 60 minutes.

  2. Fatigue mechanism verified using photovoltaic properties of Pb(Zr0.52Ti0.48)O3 thin films

    Science.gov (United States)

    Wu, Ming; Li, Wei; Li, Junning; Wang, Shaolan; Li, Yaqi; Peng, Biaolin; Huang, Haitao; Lou, Xiaojie

    2017-03-01

    The photovoltaic effect and its evolution during electrical fatigue in Pb(Zr0.52Ti0.48)O3 (PZT) thin films have been investigated. It is found that the photovoltaic effect of the as-grown PZT thin film is highly affected by the asymmetric Schottky barriers, which can be tuned by applying an external electric field. During fatigue processes, both open-circuit voltage (Voc) and short-circuit current (Jsc) decrease considerably with the increase of the number of electrical cycles. This phenomenon could be ascribed to the degradation of the interfacial layer between the thin film and the electrode induced by highly energetic charge carriers injected from the electrode during bipolar cycling. Our work sheds light on the physical mechanism of both ferroelectric photovoltaics and polarization fatigue in thin-film ferroelectrics.

  3. Upconversion photoluminescence of epitaxial Yb{sup 3+}/Er{sup 3+} codoped ferroelectric Pb(Zr,Ti)O{sub 3} films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang, E-mail: zhangy_acd@hotmail.com [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kämpfe, Thomas [Institut für Angewandte Physik, TU Dresden, 01062 Dresden (Germany); Bai, Gongxun [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China); Mietschke, Michael; Yuan, Feifei; Zopf, Michael [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Abel, Stefan [IBM Research GmbH, Saümerstrasse 4, 8803 Rüschlikon (Switzerland); Eng, Lukas M. [Institut für Angewandte Physik, TU Dresden, 01062 Dresden (Germany); Hühne, Ruben [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Fompeyrine, Jean [IBM Research GmbH, Saümerstrasse 4, 8803 Rüschlikon (Switzerland); Ding, Fei, E-mail: f.ding@ifw-dresden.de [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Schmidt, Oliver G. [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer strasse 70, 09107 Chemnitz (Germany)

    2016-05-31

    Thin films of Yb{sup 3+}/Er{sup 3+} codoped Pb(Zr,Ti)O{sub 3} (PZT:Yb/Er) have been epitaxially grown on the SrTiO{sub 3} buffered Si wafer by pulsed laser deposition. Strong upconversion photoluminescence was observed in the PZT:Yb/Er thin film. Using piezoresponse force microscopy, polar domains in the PZT:Yb/Er film can be reversibly switched with a phase change of 180°. Ferroelectric hysteresis loop shape with a well-saturated response was observed. The epitaxially grown lanthanide-doped PZT on silicon opens up a promising route to the integration of luminescent functional oxides on the silicon platform. - Highlights: • Epitaxial growth of Yb{sup 3+}/Er{sup 3+} codoped Pb(Zr,Ti)O{sub 3} films on SrTiO{sub 3} buffered silicon • Upconversion emissions were obtained from the lanthanide ion doped thin films. • Saturated ferroelectric hysteresis loops were observed. • Polar domains were switched by PFM with a phase change of 180°.

  4. Effects of oxygen partial pressure on the ferroelectric properties of pulsed laser deposited Ba0.8Sr0.2TiO3 thin films

    Science.gov (United States)

    Silva, J. P. B.; Sekhar, K. C.; Almeida, A.; Agostinho Moreira, J.; Pereira, M.; Gomes, M. J. M.

    2013-11-01

    The Ba0.8Sr0.2TiO3 thin films were grown on the Pt-Si substrate at 700 °C by using a pulsed laser deposition technique at different oxygen partial pressure (PO2) in the range of 1-20 Pa and their properties were investigated. It is observed that the PO2 during the deposition plays an important role on the tetragonal distortion ratio, surface morphology, dielectric permittivity, ferroelectric polarization, switching response, and leakage currents of the films. With an increase in PO2, the in-plane strain for the BST films changes from tensile to compressive. The films grown at 7.5 Pa show the optimum dielectric and ferroelectric properties and also exhibit the good polarization stability. It is assumed that a reasonable compressive strain, increasing the ionic displacement, and thus promotes the in-plane polarization in the field direction, could improve the dielectric permittivity. The butterfly features of the capacitance-voltage ( C- V) characteristics and the bell shape curve in polarization current were attributed to the domain reversal process. The effect of pulse amplitude on the polarization reversal behavior of the BST films grown at PO2 of 7.5 Pa was studied. The peak value of the polarization current shows exponential dependence on the electric field.

  5. Elaboration of strontium ruthenium oxide thin films on metal substrates by chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Seveno, R. [Universite de Nantes, Institut de Recherche en Electrotechnique et Electronique de Nantes Atlantique (IREENA), 2, rue de la Houssiniere, BP 92208, 44322 Nantes Cedex 3 (France)]. E-mail: raynald.seveno@univ-nantes.fr; Braud, A. [Universite de Nantes, Institut de Recherche en Electrotechnique et Electronique de Nantes Atlantique (IREENA), 2, rue de la Houssiniere, BP 92208, 44322 Nantes Cedex 3 (France); Gundel, H.W. [Universite de Nantes, Institut de Recherche en Electrotechnique et Electronique de Nantes Atlantique (IREENA), 2, rue de la Houssiniere, BP 92208, 44322 Nantes Cedex 3 (France)

    2005-12-22

    In order to improve the structural interface between a metal substrate and a lead zirconate titanate (Pb(ZrTi)O{sub 3}, PZT) ferroelectric thin film, the elaboration of strontium ruthenium oxide (SrRuO{sub 3}) by chemical solution deposition is studied. The SrRuO{sub 3} thin films were realized by multiple spin-coating technique and the temperature of the rapid thermal annealing process was optimized. The crystallization behavior was examined by X-ray diffraction; surface analyses using scanning electron microscope and atomic force microscope techniques showed the influence of the SrRuO{sub 3} layer at the interface PZT/metal on the morphology of the ferroelectric thin film. From the electrical measurements, a coercive electric field around 25 kV/cm and a remanent polarization of approximately 30 {mu}C/cm were found.

  6. Effect of Coercive Voltage and Charge Injection on Performance of a Ferroelectric-Gate Thin-Film Transistor

    Directory of Open Access Journals (Sweden)

    P. T. Tue

    2013-01-01

    Full Text Available We adopted a lanthanum oxide capping layer between semiconducting channel and insulator layers for fabrication of a ferroelectric-gate thin-film transistor memory (FGT which uses solution-processed indium-tin-oxide (ITO and lead-zirconium-titanate (PZT film as a channel layer and a gate insulator, respectively. Good transistor characteristics such as a high “on/off” current ratio, high channel mobility, and a large memory window of 108, 15.0 cm2 V−1 s−1, and 3.5 V were obtained, respectively. Further, a correlation between effective coercive voltage, charge injection effect, and FGT’s memory window was investigated. It is found that the charge injection from the channel to the insulator layer, which occurs at a high electric field, dramatically influences the memory window. The memory window’s enhancement can be explained by a dual effect of the capping layer: (1 a reduction of the charge injection and (2 an increase of effective coercive voltage dropped on the insulator.

  7. Electrode contacts on ferroelectric Pb(Zr x Ti1−x )O3 and SrBi2Ta2O9 thin films and their influence on fatigue properties

    OpenAIRE

    Lee, J. J.; Thio, C. L.; Desu, Seshu B.

    1995-01-01

    The degradation (fatigue) of dielectric properties of ferroelectric Pb(ZrxTi1-x)O-3 (PZT) and SrBi2Ta2O9 thin films during cycling was investigated. PZT and SrBi2Ta2O9 thin films were fabricated by metalorganic decomposition and pulsed laser deposition, respectively. Samples with electrodes of platinum (Pt) and ruthenium oxide (RuO2) were studied. The interfacial capacitance (if any) at the Pt/PZT, RuO2/PZT, and Pt/SrBi2Ta2O9 interfaces was determined from the thickness dependence of low-fiel...

  8. Direct observation of oxygen-vacancy-enhanced polarization in a SrTiO{sub 3}-buffered ferroelectric BaTiO{sub 3} film on GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Qiao [Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37240 (United States); Materials Science and Technology Department, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Zhang, Yuyang [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37240 (United States); Materials Science and Technology Department, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Contreras-Guerrero, Rocio; Droopad, Ravi [Ingram School of Engineering, Texas State University, San Marcos, Texas 78666 (United States); Pantelides, Sokrates T. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37240 (United States); Materials Science and Technology Department, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37240 (United States); Pennycook, Stephen J. [Department of Materials Science and Engineering, National University of Singapore, Singapore 117575 (Singapore); Ogut, Serdar; Klie, Robert F. [Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607 (United States)

    2015-11-16

    The integration of functional oxide thin-films on compound semiconductors can lead to a class of reconfigurable spin-based optoelectronic devices if defect-free, fully reversible active layers are stabilized. However, previous first-principles calculations predicted that SrTiO{sub 3} thin films grown on Si exhibit pinned ferroelectric behavior that is not switchable, due to the presence of interfacial vacancies. Meanwhile, piezoresponse force microscopy measurements have demonstrated ferroelectricity in BaTiO{sub 3} grown on semiconductor substrates. The presence of interfacial oxygen vacancies in such complex-oxide/semiconductor systems remains unexplored, and their effect on ferroelectricity is controversial. Here, we use a combination of aberration-corrected scanning transmission electron microscopy and first-principles density functional theory modeling to examine the role of interfacial oxygen vacancies on the ferroelectric polarization of a BaTiO{sub 3} thin film grown on GaAs. We demonstrate that interfacial oxygen vacancies enhance the polar discontinuity (and thus the single domain, out-of-plane polarization pinning in BaTiO{sub 3}), and propose that the presence of surface charge screening allows the formation of switchable domains.

  9. Dielectric properties of electron irradiated PbZrO 3 thin films

    Indian Academy of Sciences (India)

    The present paper deals with the study of the effects of electron (8 MeV) irradiation on the dielectric and ferroelectric properties of PbZrO3 thin films grown by sol–gel technique. The films were (0.62 m thick) subjected to electron irradiation using Microtron accelerator (delivered dose 80, 100, 120 kGy). The films were well ...

  10. Room Temperature Tunable Multiferroic Properties in Sol-Gel-Derived Nanocrystalline Sr(Ti1−xFexO3−δ Thin Films

    Directory of Open Access Journals (Sweden)

    Yi-Guang Wang

    2017-09-01

    Full Text Available Sr(Ti1−xFexO3−δ (0 ≤ x ≤ 0.2 thin films were grown on Si(100 substrates with LaNiO3 buffer-layer by a sol-gel process. Influence of Fe substitution concentration on the structural, ferroelectric, and magnetic properties, as well as the leakage current behaviors of the Sr(Ti1−xFexO3−δ thin films, were investigated by using the X-ray diffractometer (XRD, atomic force microscopy (AFM, the ferroelectric test system, and the vibrating sample magnetometer (VSM. After substituting a small amount of Ti ion with Fe, highly enhanced ferroelectric properties were obtained successfully in SrTi0.9Ti0.1O3−δ thin films, with a double remanent polarization (2Pr of 1.56, 1.95, and 9.14 μC·cm−2, respectively, for the samples were annealed in air, oxygen, and nitrogen atmospheres. The leakage current densities of the Fe-doped SrTiO3 thin films are about 10−6–10−5 A·cm−2 at an applied electric field of 100 kV·cm−1, and the conduction mechanism of the thin film capacitors with various Fe concentrations has been analyzed. The ferromagnetic properties of the Sr(Ti1−xFexO3−δ thin films have been investigated, which can be correlated to the mixed valence ions and the effects of the grain boundary. The present results revealed the multiferroic nature of the Sr(Ti1−xFexO3−δ thin films. The effect of the annealing environment on the room temperature magnetic and ferroelectric properties of Sr(Ti0.9Fe0.1O3−δ thin films were also discussed in detail.

  11. Mechanism of polarization switching in wurtzite-structured zinc oxide thin films

    Science.gov (United States)

    Konishi, Ayako; Ogawa, Takafumi; Fisher, Craig A. J.; Kuwabara, Akihide; Shimizu, Takao; Yasui, Shintaro; Itoh, Mitsuru; Moriwake, Hiroki

    2016-09-01

    The properties of a potentially new class of ferroelectric materials based on wurtzite-structured ZnO thin films are examined using the first-principles calculations. Theoretical P-E hysteresis loops were calculated using the fixed-D method for both unstrained and (biaxially) strained single crystals. Ferroelectric polarization switching in ZnO (S.G. P63mc) is shown to occur via an intermediate non-polar structure with centrosymmetric P63/mmc symmetry by displacement of cations relative to anions in the long-axis direction. The calculated coercive electric field (Ec) for polarization switching was estimated to be 7.2 MV/cm for defect-free monocrystalline ZnO. During switching, the short- and long-axis lattice parameters expand and contract, respectively. The large structural distortion required for switching may explain why ferroelectricity in this compound has not been reported experimentally for pure ZnO. Applying an epitaxial tensile strain parallel to the basal plane is shown to be effective in lowering Ec during polarization, with a 5% biaxial expansion resulting in a decrease of Ec to 3.5 MV/cm. Comparison with calculated values for conventional ferroelectric materials suggests that the ferroelectric polarization switching of wurtzite-structured ZnO may be achievable by preparing high-quality ZnO thin films with suitable strain levels and low defect concentrations.

  12. Chemical segregation and self polarisation in ferroelectrics

    Directory of Open Access Journals (Sweden)

    Bernard E. Watts

    2009-06-01

    Full Text Available Chemical partitioning or segregation is commonly encountered in solid-state syntheses. It is driven by compositional, thermal and electric field gradients. These phenomena can be quite extreme in thin films and lead to notable effects on the electrical properties of ferroelectrics. The segregation in ferroelectric thin films will be illustrated and the mechanisms explained in terms of diffusion processes driven by a potential gradient of the oxygen. The hypothesis can also explain self polarisation and imprint in ferroelectric hysteresis.

  13. Combined effect of preferential orientation and Zr/Ti atomic ratio on electrical properties of Pb(ZrxTi1-x)O3 thin films

    International Nuclear Information System (INIS)

    Gong Wen; Li Jingfeng; Chu Xiangcheng; Gui Zhilun; Li Longtu

    2004-01-01

    Lead zirconate titanate [Pb(Zr x Ti 1-x )O 3 , PZT] thin films with various compositions, whose Zr/Ti ratio were varied as 40/60, 48/52, 47/53, and 60/40, were deposited on Pt(111)/Ti/SiO 2 /Si substrates by sol-gel method. A seeding layer was introduced between the PZT layer and the bottom electrode to control the texture of overlaid PZT thin films. A single perovskite PZT thin film with absolute (100) texture was obtained, when lead oxide was used as the seeding crystal, whereas titanium dioxide resulted in highly [111]-oriented PZT films. The dielectric and ferroelectric properties of PZT films with different preferential orientations were evaluated systemically as a function of composition. The maximums of relative dielectric constant were obtained in the morphotropic phase boundary region for both (100)- and (111)-textured PZT films. The ferroelectric properties also greatly depend on films' texture and composition. The intrinsic and extrinsic contributions to dielectric and ferroelectric properties were discussed

  14. Pyroelectric properties of finite size ferroelectric thin films with structural transition zones

    International Nuclear Information System (INIS)

    Zhou Jing; Lue Tianquan; Sun Punan; Xie Wenguang; Cao Wenwu

    2009-01-01

    A Fermi-type Green's function is used to study pyroelectric properties of the thin film with finite sizes in three dimensions based on a modified transverse Ising model. The results demonstrate that a decrease in the lateral size of the film has a disadvantageous influence on the pyroelectric coefficient of the thin film.

  15. Evidence for oxygen vacancy or ferroelectric polarization induced switchable diode and photovoltaic effects in BiFeO3 based thin films

    International Nuclear Information System (INIS)

    Guo Yiping; Guo Bing; Dong Wen; Li Hua; Liu Hezhou

    2013-01-01

    The diode and photovoltaic effects of BiFeO 3 and Bi 0.9 Sr 0.1 FeO 3−δ polycrystalline thin films were investigated by poling the films with increased magnitude and alternating direction. It was found that both electromigration of oxygen vacancies and polarization flipping are able to induce switchable diode and photovoltaic effects. For the Bi 0.9 Sr 0.1 FeO 3−δ thin films with high oxygen vacancy concentration, reversibly switchable diode and photovoltaic effects can be observed due to the electromigration of oxygen vacancies under an electric field much lower than its coercive field. However, for the pure BiFeO 3 thin films with lower oxygen vacancy concentration, the reversibly switchable diode and photovoltaic effect is hard to detect until the occurrence of polarization flipping. The switchable diode and photovoltaic effects can be explained well using the concepts of Schottky-like barrier-to-Ohmic contacts resulting from the combination of oxygen vacancies and polarization. The sign of photocurrent could be independent of the direction of polarization when the modulation of the energy band induced by oxygen vacancies is large enough to offset that induced by polarization. The photovoltaic effect induced by the electromigration of oxygen vacancies is unstable due to the diffusion of oxygen vacancies or the recombination of oxygen vacancies with hopping electrons. Our work provides deep insights into the nature of diode and photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities. (paper)

  16. Development and construction of a novel MOCVD facility for the growth of ferroelectric thin layers

    International Nuclear Information System (INIS)

    Schaefer, P.R.

    2002-02-01

    This thesis deals with the production of ferroelectric thin films using the MOCVD technology. The main focus is put on the design and construction of a complete MOCVD research system that is equipped with a novel non-contact vaporizer system. The precursors are nebulized in an ultrasonic atomizer and injected into a hot gas stream, so they can vaporize without getting into contact with a hot surface. Hence, one of the biggest disadvantages of conventional vaporizer concepts, the contamination of the vaporizing element with decomposing chemicals, could be avoided completely, resulting in a nearly maintenance-free system. In a direct comparison with the well-established Direct Liquid Injection Subsystem DLI-25C from MKS Instruments, the advantages of non-contact evaporation were clearly demonstrated. Additionally, the scope of this work included the development of standard deposition processes for the ternary oxides SrTiO 3 , BaTiO 3 und PbTiO 3 and growth studies were performed. Electrical measurements performed on MIM structures with Pt electrodes and SrTiO 3 as dielectric indicate a high film quality comparable with results presented in the literature. Furthermore, for the first time the solid solution (Pb x Ba 1-x )TiO 3 has been deposited by MOCVD. This material system is widely unknown in thin film form and it is well suited as a model system to investigate the influence of mechanical stresses on the film properties, because it represents a transition between the (as a thin film) superparaelectric barium titanate and the ferroelectric lead titanate. Through variation of the lead/barium ratio the tetragonal distortion of the lattice cell could be adjusted in a wide range. (orig.)

  17. Microscopic local fatigue in PZT thin films

    International Nuclear Information System (INIS)

    Li, B S; Wu, A; Vilarinho, P M

    2007-01-01

    The reduction in switchable polarization during fatigue largely limits the application of PZT thin films in ferroelectric nonvolatile memories. So, it is very important to understand the fatigue mechanism in PZT films, especially at a nanoscale level. In this paper, nanoscale fatigue properties in PZT thin films have been studied by piezoresponse force microscopy and local piezoloops. It has been found that a piezoloop obtained on a fatigued point exhibits a much more pinched shape and a local imprint phenomenon is observed after severe fatigue. Furthermore, the domain structure evolves from a simple single-peak profile to a complex fluctuant one. However, there is only some shift of the piezoloop when a unipolar field with the same amplitude is applied on the film. The available experimental data show that there exist obvious domain wall pinning and injection of electrons into the film during fatigue. Finally, a schematic illustration is suggested to explain the possible fatigue mechanism

  18. Tunable Microwave Filter Design Using Thin-Film Ferroelectric Varactors

    Science.gov (United States)

    Haridasan, Vrinda

    Military, space, and consumer-based communication markets alike are moving towards multi-functional, multi-mode, and portable transceiver units. Ferroelectric-based tunable filter designs in RF front-ends are a relatively new area of research that provides a potential solution to support wideband and compact transceiver units. This work presents design methodologies developed to optimize a tunable filter design for system-level integration, and to improve the performance of a ferroelectric-based tunable bandpass filter. An investigative approach to find the origins of high insertion loss exhibited by these filters is also undertaken. A system-aware design guideline and figure of merit for ferroelectric-based tunable band- pass filters is developed. The guideline does not constrain the filter bandwidth as long as it falls within the range of the analog bandwidth of a system's analog to digital converter. A figure of merit (FOM) that optimizes filter design for a specific application is presented. It considers the worst-case filter performance parameters and a tuning sensitivity term that captures the relation between frequency tunability and the underlying material tunability. A non-tunable parasitic fringe capacitance associated with ferroelectric-based planar capacitors is confirmed by simulated and measured results. The fringe capacitance is an appreciable proportion of the tunable capacitance at frequencies of X-band and higher. As ferroelectric-based tunable capac- itors form tunable resonators in the filter design, a proportionally higher fringe capacitance reduces the capacitance tunability which in turn reduces the frequency tunability of the filter. Methods to reduce the fringe capacitance can thus increase frequency tunability or indirectly reduce the filter insertion-loss by trading off the increased tunability achieved to lower loss. A new two-pole tunable filter topology with high frequency tunability (> 30%), steep filter skirts, wide stopband

  19. Ferroelectric properties of sandwich structured (Bi, La)4T3O12/Pb(Zr, Ti)O3/ (Bi, La)4Ti3O12 thin films on Pt/Ti/SiO2/Si substrates

    International Nuclear Information System (INIS)

    Bao Dinghua; Wakiya, Naoki; Shinozaki, Kazuo; Mizutani, Nobuyasu

    2002-01-01

    Sandwich structured (Bi, La) 4 Ti 3 O 12 /Pb(Zr, Ti)O 3 /(Bi, La) 4 Ti 3 O 12 thin films were fabricated on Pt/Ti/SiO 2 /Si substrates, with the intention of simultaneously utilizing the advantages of both (Bi, La) 4 Ti 3 O 12 (BLT) and Pb(Zr, Ti)O 3 (PZT) thin films such as non-fatigue behaviours of BLT and good ferroelectric properties of PZT. Both BLT and PZT layers were prepared by a chemical solution deposition technique. The experiments demonstrated that the sandwich structure showed fatigue-free characteristics at least up to 10 10 switching bipolar pulse cycles under 8 V and excellent retention properties. The sandwich structured thin films also exhibited well-defined hysteresis loops with a remanent polarization (2P r ) of 8.8 μC cm -2 and a coercive field (E c ) of 47 kV cm -1 . The room-temperature dielectric constant and dissipation factor were 210 and 0.031, respectively, at a frequency of 100 kHz. These results suggest that this sandwich structure is a promising material combination for ferroelectric memory applications. (author)

  20. Ferroelectric-gate field effect transistor memories device physics and applications

    CERN Document Server

    Ishiwara, Hiroshi; Okuyama, Masanori; Sakai, Shigeki; Yoon, Sung-Min

    2016-01-01

    This book provides comprehensive coverage of the materials characteristics, process technologies, and device operations for memory field-effect transistors employing inorganic or organic ferroelectric thin films. This transistor-type ferroelectric memory has interesting fundamental device physics and potentially large industrial impact. Among the various applications of ferroelectric thin films, the development of nonvolatile ferroelectric random access memory (FeRAM) has progressed most actively since the late 1980s and has achieved modest mass production levels for specific applications since 1995. There are two types of memory cells in ferroelectric nonvolatile memories. One is the capacitor-type FeRAM and the other is the field-effect transistor (FET)-type FeRAM. Although the FET-type FeRAM claims ultimate scalability and nondestructive readout characteristics, the capacitor-type FeRAMs have been the main interest for the major semiconductor memory companies, because the ferroelectric FET has fatal handic...

  1. Characterization of PZT thin films on metal substrates

    International Nuclear Information System (INIS)

    Dutschke, A.

    2008-01-01

    Lead zirconate titanate (PbZr x Ti 1-x O 3 ,PZT) is one of the most applied ceramic materials because of its distinctive piezo- and ferroelectric properties. Prepared as thin films on flexible, metallic substrates it can be used for various applications as strain gauges, key switches, vibration dampers, microactuators and ultrasonic transducers. The aim of this work is to analyze the microstructure and the phase-content of PZT-thin films deposited on temperature- und acid-resistant hastelloy-sheets, to correlate the results with the ferroelectric and dielectric properties. It is demonstrated, that the specific variation of the microstructure can be achieved by different thermal treatments and the selective addition of Neodymium as dopant. Nd-doping leads to a shift of the maximum nucleation rate towards reduced temperatures and a decrease in the rate of growth compared to undoped films. The PZT-films are prepared by a sol-gel-process in fourfold multilayers with a composition near the morphotropic phase boundary, where the tetragonal und rhombohedral perovskite-phases coexist. The crystallisation in Nd-doped and undoped films takes place heterogeneously, preferentially at the interfaces and on the surface of the multilayered films as well as on the inner surface of pores within the films. For the first time, the Zr:Ti fluctuation phenomena emerging in sol-gel derived PZT films is related to the microstructure and the local phase content on a nanometer scale. In this connection it is proved, that long-distance Zr:Ti gradients arise preferentially before and during the crystallisation of the pyrochlore phase. During the following crystallisation of the perovskite phase, the crystallites grow across these gradients without modifying them. It is pointed out that the fluctuation in the Zr:Ti ratio has only minor influence on the amount of the tetragonal or rhombohedral distortion of the crystallites after the transition from the para- to the ferroelectric state due to

  2. Polarization-tuned diode behaviour in multiferroic BiFeO3 thin films

    KAUST Repository

    Yao, Yingbang; Zhang, Bei; Chen, Long; Yang, Yang; Wang, Zhihong; Alshareef, Husam N.; Zhang, Xixiang

    2012-01-01

    Asymmetric rectifying I-V behaviour of multiferroic BiFeO3 (BFO) thin films grown on transparent ITO-coated glass was quantitatively studied as a function of ferroelectric polarization. Different polarized states were established by unipolar

  3. Ferroelectric materials and their applications

    CERN Document Server

    Xu, Y

    2013-01-01

    This book presents the basic physical properties, structure, fabrication methods and applications of ferroelectric materials. These are widely used in various devices, such as piezoelectric/electrostrictive transducers and actuators, pyroelectric infrared detectors, optical integrated circuits, optical data storage, display devices, etc. The ferroelectric materials described in this book include a relatively complete list of practical and promising ferroelectric single crystals, bulk ceramics and thin films. Included are perovskite-type, lithium niobate, tungsten-bronze-type, water-soluable

  4. Switching characteristics for ferroelectric random access memory based on RC model in poly(vinylidene fluoride-trifluoroethylene) ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, ChangLi [Department of Physics, East China University of Science and Technology, Shanghai 200237 (China); Complex and Intelligent System Research Center, East China University of Science and Technology, Shanghai 200237 (China); Wang, XueJun [Complex and Intelligent System Research Center, East China University of Science and Technology, Shanghai 200237 (China); Zhang, XiuLi [Department of Physics, East China University of Science and Technology, Shanghai 200237 (China); School of Fundamental Studies, Shanghai University of Engineering Science, Shanghai 201620 (China); Du, XiaoLi [School of Fundamental Studies, Shanghai University of Engineering Science, Shanghai 201620 (China); Xu, HaiSheng, E-mail: hsxu@ecust.edu.cn [Department of Physics, East China University of Science and Technology, Shanghai 200237 (China); Kunshan Hisense Electronics Co., Ltd., Kunshan, Jiangsu 215300 (China)

    2016-05-15

    The switching characteristic of the poly(vinylidene fluoride-trifluoroethlene) (P(VDF-TrFE)) films have been studied at different ranges of applied electric field. It is suggest that the increase of the switching speed upon nucleation protocol and the deceleration of switching could be related to the presence of a non-ferroelectric layer. Remarkably, a capacitor and resistor (RC) links model plays significant roles in the polarization switching dynamics of the thin films. For P(VDF-TrFE) ultrathin films with electroactive interlayer, it is found that the switching dynamic characteristics are strongly affected by the contributions of resistor and non-ferroelectric (non-FE) interface factors. A corresponding experiment is designed using poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic) (PEDOT-PSSH) as interlayer with different proton concentrations, and the testing results show that the robust switching is determined by the proton concentration in interlayer and lower leakage current in circuit to reliable applications of such polymer films. These findings provide a new feasible method to enhance the polarization switching for the ferroelectric random access memory.

  5. Switching characteristics for ferroelectric random access memory based on RC model in poly(vinylidene fluoride-trifluoroethylene) ultrathin films

    International Nuclear Information System (INIS)

    Liu, ChangLi; Wang, XueJun; Zhang, XiuLi; Du, XiaoLi; Xu, HaiSheng

    2016-01-01

    The switching characteristic of the poly(vinylidene fluoride-trifluoroethlene) (P(VDF-TrFE)) films have been studied at different ranges of applied electric field. It is suggest that the increase of the switching speed upon nucleation protocol and the deceleration of switching could be related to the presence of a non-ferroelectric layer. Remarkably, a capacitor and resistor (RC) links model plays significant roles in the polarization switching dynamics of the thin films. For P(VDF-TrFE) ultrathin films with electroactive interlayer, it is found that the switching dynamic characteristics are strongly affected by the contributions of resistor and non-ferroelectric (non-FE) interface factors. A corresponding experiment is designed using poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic) (PEDOT-PSSH) as interlayer with different proton concentrations, and the testing results show that the robust switching is determined by the proton concentration in interlayer and lower leakage current in circuit to reliable applications of such polymer films. These findings provide a new feasible method to enhance the polarization switching for the ferroelectric random access memory.

  6. Controlling the properties of ferroelectric-nickelate interfaces

    Science.gov (United States)

    Marshall, Matthew S. J.; Malashevich, Andrei; Disa, Ankit; Han, Myung-Geun; Zhu, Yimei; Ismail-Beigi, Sohrab; Walker, Frederick; Ahn, Charles

    2015-03-01

    Ferroelectrics are a class of materials that exhibit a stable, reversible polarization making them useful for non-volatile electronic devices. In devices consisting of thin film ferroelectric PZT acting as a gate and a thin film of the conductive oxide LaNiO3 grown on LaAlO3(001) acting as a channel, we have realized a large change in room temperature channel resistance by switching the ferroelectric polarization. The effect of switching the polarization of the ferroelectric is to modify the electronic structure of the interface between the gate and channel, resulting in conduction in the otherwise insulating ferroelectric. Here, we discuss how changing the epitaxial strain and interface termination of LaNiO3 can result in larger changes in resistivity. The epitaxial strain is varied by growing the devices on LaAlO3 for tensile strain and SrTiO3 for compressive strain. An interface termination of either an atomic layer of NiO2 or LaO is achieved via atomic layering using oxygen plasma assisted molecular beam epitaxy (MBE).

  7. Pulsed Laser Deposition of BaTiO3 Thin Films on Different Substrates

    Directory of Open Access Journals (Sweden)

    Yaodong Yang

    2010-01-01

    Full Text Available We have studied the deposition of BaTiO3 (BTO thin films on various substrates. Three representative substrates were selected from different types of material systems: (i SrTiO3 single crystals as a typical oxide, (ii Si wafers as a semiconductor, and (iii Ni foils as a magnetostrictive metal. We have compared the ferroelectric properties of BTO thin films obtained by pulsed laser deposition on these diverse substrates.

  8. Electrical properties of ferroelectric YMnO3 films deposited on n-type Si(111) substrates

    International Nuclear Information System (INIS)

    Parashar, S; Raju, A R; Rao, C N R; Victor, P; Krupanidhi, S B

    2003-01-01

    YMnO 3 thin films were grown on an n-type Si substrate by nebulized spray pyrolysis in the metal-ferroelectric-semiconductor (MFS) configuration. The capacitance-voltage characteristics of the film in the MFS structure exhibit hysteretic behaviour consistent with the polarization charge switching direction, with the memory window decreasing with increase in temperature. The density of the interface states decreases with increasing annealing temperature. Mapping of the silicon energy band gap with the interface states has been carried out. The leakage current, measured in the accumulation region, is lower in well-crystallized thin films and obeys a space-charge limited conduction mechanism. The calculated activation energy from the dc leakage current characteristics of the Arrhenius plot reveals that the activation energy corresponds to oxygen vacancy motion

  9. Room Temperature Thin Film Ba(x)Sr(1-x)TiO3 Ku-Band Coupled MicrostripPhase Shifters: Effects of Film Thickness, Doping, Annealing and Substrate Choice

    Science.gov (United States)

    VanKeuls, F. W.; Mueller, C. H.; Miranda, F. A.; Romanofsky, R. R.; Canedy, C. L.; Aggarwal, S.; Venkatesan, T.; Ramesh, R.; Horwitz, S.; Chang, W.

    1999-01-01

    We report on measurements taken on over twenty Ku-band coupled microstrip phase shifters (CMPS) using thin ferroelectric films of Ba(x)Sr(1-x)TiO3. This CMPS design is a recent innovation designed to take advantage of the high tunability and tolerate the high dielectric constant of ferroelectric films at Ku- and K-band frequencies. These devices are envisioned as a component in low-cost steerable beam phased area antennas, Comparisons are made between devices with differing film thickness, annealed vs unannealed, Mn-doped vs. undoped, and also substrates of LaAlO3 and MgO. A comparison between the CMPS structure and a CPW phase shifter was also made oil the same ferroelectric film.

  10. Theoretical Methods of Domain Structures in Ultrathin Ferroelectric Films: A Review

    Directory of Open Access Journals (Sweden)

    Jianyi Liu

    2014-09-01

    Full Text Available This review covers methods and recent developments of the theoretical study of domain structures in ultrathin ferroelectric films. The review begins with an introduction to some basic concepts and theories (e.g., polarization and its modern theory, ferroelectric phase transition, domain formation, and finite size effects, etc. that are relevant to the study of domain structures in ultrathin ferroelectric films. Basic techniques and recent progress of a variety of important approaches for domain structure simulation, including first-principles calculation, molecular dynamics, Monte Carlo simulation, effective Hamiltonian approach and phase field modeling, as well as multiscale simulation are then elaborated. For each approach, its important features and relative merits over other approaches for modeling domain structures in ultrathin ferroelectric films are discussed. Finally, we review recent theoretical studies on some important issues of domain structures in ultrathin ferroelectric films, with an emphasis on the effects of interfacial electrostatics, boundary conditions and external loads.

  11. Effects of {sup 60}Co γ-ray irradiation on microstructure and ferroelectric properties of Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zan [Shenyang University of Technology, Shenyang 110870 (China); Shenyang University of Chemical Technology, Shenyang 110142 (China); Jiang, Wei, E-mail: weijiang.sut.edu@gmail.com [Shenyang University of Technology, Shenyang 110870 (China); Li, San-xi [Shenyang University of Technology, Shenyang 110870 (China); Tong, Jun-sheng [Liaoning Provincial Academy of Agricultural Science Radiation Center, 110142 (China)

    2016-01-01

    Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} (BLT) thin films were deposited on Pt/Ti/SiO{sub 2}/Si substrates through sol–gel method. Films underwent {sup 60}Co γ-ray irradiation with different doses; 0, 50, 100 and 150 kGy, respectively. Impacts of γ-ray on the microstructure, ferroelectric properties, leakage current density and fatigue characteristic were studied in detail. The results of SEM images show that grain patterns become irregular. Remnant polarization (2Pr) and coercive field (2Ec) decrease with irradiation dose increase. C–V curves reveal obvious asymmetry along y-axis. The irradiated thin films display lower leakage current density and fatigue endurance up to more than 10{sup 10} switching cycles. These results suggest that radiation can improve the film performance in some areas.

  12. The single-phase multiferroic oxides: from bulk to thin film

    International Nuclear Information System (INIS)

    Prellier, W; Singh, M P; Murugavel, P

    2005-01-01

    Complex perovskite oxides exhibit a rich spectrum of properties, including magnetism, ferroelectricity, strongly correlated electron behaviour, superconductivity and magnetoresistance, which have been research areas of great interest among the scientific and technological community for decades. There exist very few materials which exhibit multiple functional properties; one such class of materials is called the multiferroics. Multiferroics are interesting because they exhibit simultaneously ferromagnetic and ferroelectric polarizations and a coupling between them. Due to the nontrivial lattice coupling between the magnetic and electronic domains (the magnetoelectric effect), the magnetic polarization can be switched by applying an electric field; likewise the ferroelectric polarization can be switched by applying a magnetic field. As a consequence, multiferroics offer rich physics and novel devices concepts, which have recently become of great interest to researchers. In this review article the recent experimental status, for both the bulk single phase and the thin film form, has been presented. Current studies on the ceramic compounds in the bulk form including Bi(Fe,Mn)O 3 , REMnO 3 and the series of REMn 2 O 5 single crystals (RE = rare earth) are discussed in the first section and a detailed overview on multiferroic thin films grown artificially (multilayers and nanocomposites) is presented in the second section. (topical review)

  13. Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method.

    Science.gov (United States)

    Jo, Seo-Hyeon; Lee, Sung-Gap; Lee, Young-Hie

    2012-01-05

    In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2.

  14. Orientation control and domain structure analysis of {100}-oriented epitaxial ferroelectric orthorhombic HfO{sub 2}-based thin films

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Kiliha [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Shimizu, Takao [Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Sakata, Osami [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Shiraishi, Takahisa; Nakamura, Shogo; Kiguchi, Takanori; Akama, Akihiro; Konno, Toyohiko J. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Uchida, Hiroshi [Department of Materials and Life Sciences, Sophia University, Chiyoda, Tokyo 102-8554 (Japan); Funakubo, Hiroshi, E-mail: funakubo.h.aa@m.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2016-04-07

    Orientation control of {100}-oriented epitaxial orthorhombic 0.07YO{sub 1.5}-0.93HfO{sub 2} films grown by pulsed laser deposition was investigated. To achieve in-plane lattice matching, indium tin oxide (ITO) and yttria-stabilized zirconia (YSZ) were selected as underlying layers. We obtained (100)- and (001)/(010)-oriented films on ITO and YSZ, respectively. Ferroelastic domain formation was confirmed for both films by X-ray diffraction using the superlattice diffraction that appeared only for the orthorhombic symmetry. The formation of ferroelastic domains is believed to be induced by the tetragonal–orthorhombic phase transition upon cooling the films after deposition. The present results demonstrate that the orientation of HfO{sub 2}-based ferroelectric films can be controlled in the same manner as that of ferroelectric films composed of conventional perovskite-type material such as Pb(Zr, Ti)O{sub 3} and BiFeO{sub 3}.

  15. The origin of local strain in highly epitaxial oxide thin films.

    Science.gov (United States)

    Ma, Chunrui; Liu, Ming; Chen, Chonglin; Lin, Yuan; Li, Yanrong; Horwitz, J S; Jiang, Jiechao; Meletis, E I; Zhang, Qingyu

    2013-10-31

    The ability to control the microstructures and physical properties of hetero-epitaxial functional oxide thin films and artificial structures is a long-sought goal in functional materials research. Normally, only the lattice misfit between the film and the substrate is considered to govern the physical properties of the epitaxial films. In fact, the mismatch of film unit cell arrangement and the Surface-Step-Terrace (SST) dimension of the substrate, named as "SST residual matching", is another key factor that significantly influence the properties of the epitaxial film. The nature of strong local strain induced from both lattice mismatch and the SST residual matching on ferroelectric (Ba,Sr)TiO3 and ferromagnetic (La,Ca)MnO3 thin films are systematically investigated and it is demonstrated that this combined effect has a dramatic impact on the physical properties of highly epitaxial oxide thin films. A giant anomalous magnetoresistance effect (~10(10)) was achieved from the as-designed vicinal surfaces.

  16. Pyroelectricity of silicon-doped hafnium oxide thin films

    Science.gov (United States)

    Jachalke, Sven; Schenk, Tony; Park, Min Hyuk; Schroeder, Uwe; Mikolajick, Thomas; Stöcker, Hartmut; Mehner, Erik; Meyer, Dirk C.

    2018-04-01

    Ferroelectricity in hafnium oxide thin films is known to be induced by various doping elements and in solid-solution with zirconia. While a wealth of studies is focused on their basic ferroelectric properties and memory applications, thorough studies of the related pyroelectric properties and their application potential are only rarely found. This work investigates the impact of Si doping on the phase composition and ferro- as well as pyroelectric properties of thin film capacitors. Dynamic hysteresis measurements and the field-free Sharp-Garn method were used to correlate the reported orthorhombic phase fractions with the remanent polarization and pyroelectric coefficient. Maximum values of 8.21 µC cm-2 and -46.2 µC K-1 m-2 for remanent polarization and pyroelectric coefficient were found for a Si content of 2.0 at%, respectively. Moreover, temperature-dependent measurements reveal nearly constant values for the pyroelectric coefficient and remanent polarization over the temperature range of 0 ° C to 170 ° C , which make the material a promising candidate for IR sensor and energy conversion applications beyond the commonly discussed use in memory applications.

  17. Optical refraction index and polarization profile of ferroelectric thin films

    Czech Academy of Sciences Publication Activity Database

    Glinchuk, M. D.; Eliseev, E. A.; Deineka, Alexander; Jastrabík, Lubomír; Suchaneck, G.; Sandner, T.; Gerlach, G.; Hrabovský, Miroslav

    2001-01-01

    Roč. 38, 1-4 (2001), s. 101-110 ISSN 1058-4587 R&D Projects: GA MŠk LN00A015; GA ČR GA202/00/1425 Institutional research plan: CEZ:AV0Z1010914 Keywords : thin film * refraction index * polarization * film thickness Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.512, year: 2001

  18. Vacuum-evaporated ferroelectric films and heterostructures of vinylidene fluoride/trifluoroethylene copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Draginda, Yu. A., E-mail: lbf@ns.crys.ras.ru; Yudin, S G; Lazarev, V V; Yablonskii, S V; Palto, S P [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2012-05-15

    The potential of the vacuum method for preparing ferroelectric films and photonic heterostructures from organic materials is studied. Vacuum-evaporated films of fluoropolymers and heterostructures on their basis are obtained and their ferroelectric and spectral properties are studied. In particular, homogeneous films of the well-known piezoelectric polymer polyvinylidene fluoride and ferroelectric material vinylidene fluoride/trifluoroethylene copolymer (P(VDF/TFE)) are produced. Experimental studies of vacuum-evaporated P(VDF/TFE) films confirmed their ferroelectric properties. The heterostructures composed of alternating layers of P(VDF/TFE) copolymer molecules and azodye molecules are fabricated by vacuum evaporation. Owing to the controlled layer thickness and a significant difference in the refractive indices of the P(VDF/TFE) copolymer and azodyes, these heterostructures exhibit properties of photonic crystals. This finding is confirmed by the occurrence of a photonic band in the absorption spectra of the heterostructures.

  19. Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3-(K0.5Na0.5)0.4(Sr 0.6Ba0.4)0.8Nb2O6 thin films

    KAUST Repository

    Yao, Yingbang

    2014-02-01

    Multiferroic BiFeO3-(K0.5Na0.5) 0.4(Sr0.6Ba0.4)0.8Nb 2O6 (BFO-KNSBN) trilayer thin films, were epitaxially grown on MgO(0 0 1) and SrTiO3(0 0 1) by using pulsed laser deposition (PLD). Their ferroelectric, magnetic, dielectric and optical properties were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis magnetic loop was observed in the KNSBN-BFO-KNSBN trilayer films, where exchange bias and secondary phase in the BFO layer played crucial roles. Interactions between adjacent layers were revealed by temperature-dependent Raman spectroscopic measurements. © 2013 Elsevier B.V. All rights reserved.

  20. Effect of thermal strain on the ferroelectric phase transition in polycrystalline Ba0.5Sr0.5TiO3 thin films studied by Raman spectroscopy

    International Nuclear Information System (INIS)

    Tenne, D.A.; Soukiassian, A.; Xi, X.X.; Taylor, T.R.; Hansen, P.J.; Speck, J.S.; York, R.A.

    2004-01-01

    We have applied Raman spectroscopy to study the influence of thermal strain on the vibrational properties of polycrystalline Ba 0.5 Sr 0.5 TiO 3 films. The films were grown by rf magnetron sputtering on Pt/SiO 2 surface using different host substrates: strontium titanate, sapphire, silicon, and vycor glass. These substrates provide a systematic change in the thermal strain while maintaining the same film microstructure. From the temperature dependence of the ferroelectric A 1 soft phonon intensity, the ferroelectric phase transition temperature, T C , was determined. We found that T C decreases with increasing tensile stress in the films. This dependence is different from the theoretical predictions for epitaxial ferroelectric films. The reduction of the ferroelectric transition temperature with increasing biaxial tensile strain is attributed to the suppression of in-plane polarization due to the small lateral grain size in the films

  1. Dipole pinning effect on photovoltaic characteristics of ferroelectric BiFeO3 films

    Science.gov (United States)

    Biswas, P. P.; Thirmal, Ch.; Pal, S.; Murugavel, P.

    2018-01-01

    Ferroelectric bismuth ferrite is an attractive candidate for switchable devices. The effect of dipole pinning due to the oxygen vacancy layer on the switching behavior of the BiFeO3 thin film fabricated by the chemical solution deposition method was studied after annealing under air, O2, and N2 environment. The air annealed film showed well defined and dense grains leading to a lower leakage current and superior electrical properties compared to the other two films. The photovoltage and transient photocurrent measured under positive and negative poling elucidated the switching nature of the films. Though the air and O2 annealed films showed a switchable photovoltaic response, the response was severely affected by oxygen vacancies in the N2 annealed film. In addition, the open circuit voltage was found to be mostly dependent on the polarization of BiFeO3 rather than the Schottky barriers at the interface. This work provides an important insight into the effect of dipole pinning caused by oxygen vacancies on the switchable photovoltaic effect of BiFeO3 thin films along with the importance of stoichiometric, defect free, and phase pure samples to facilitate meaningful practical applications.

  2. Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abazari, M; Safari, A [Glenn Howatt Electroceramics Laboratories, Department of Materials Science and Engineering, Rutgers-The state University of New Jersey, Piscataway, NJ 08854 (United States); Choi, T; Cheong, S-W [Rutgers Center for Emergent Materials, Department of Physics and Astronomy, Rutgers-The state University of New Jersey, Piscataway, NJ 08854 (United States)

    2010-01-20

    We report the observation of domain structure and piezoelectric properties of pure and Mn-doped (K{sub 0.44},Na{sub 0.52},Li{sub 0.04})(Nb{sub 0.84},Ta{sub 0.1},Sb{sub 0.06})O{sub 3} (KNN-LT-LS) thin films on SrTiO{sub 3} substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180{sup 0} domains. This was in accordance with the tetragonal structure of the films, confirmed by relative permittivity measurements and x-ray diffraction patterns. Effective piezoelectric coefficient (d{sub 33}) of the films were calculated using piezoelectric displacement curves and shown to be {approx}53 pm V{sup -1} for pure KNN-LT-LS thin films. This value is among the highest values reported for an epitaxial lead-free thin film and shows a great potential for KNN-LT-LS to serve as an alternative to PZT thin films in future applications.

  3. Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films

    Science.gov (United States)

    Abazari, M.; Choi, T.; Cheong, S.-W.; Safari, A.

    2010-01-01

    We report the observation of domain structure and piezoelectric properties of pure and Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180° domains. This was in accordance with the tetragonal structure of the films, confirmed by relative permittivity measurements and x-ray diffraction patterns. Effective piezoelectric coefficient (d33) of the films were calculated using piezoelectric displacement curves and shown to be ~53 pm V-1 for pure KNN-LT-LS thin films. This value is among the highest values reported for an epitaxial lead-free thin film and shows a great potential for KNN-LT-LS to serve as an alternative to PZT thin films in future applications.

  4. Ferroelectric properties of NaNbO3-BaTiO3 thin films deposited on SrRuO3/(001)SrTiO3 substrate by pulsed laser deposition

    International Nuclear Information System (INIS)

    Yamazoe, Seiji; Oda, Shinya; Sakurai, Hiroyuki; Wada, Takahiro; Adachi, Hideaki

    2009-01-01

    (NaNbO 3 ) 1-x (BaTiO 3 ) x (NN-xBT) thin films with low BaTiO 3 (BT) concentrations x (x=0.05 and 0.10) were fabricated on SrRuO 3 /(001)SrTiO 3 (SRO)/(001)STO) substrate by pulsed laser deposition (PLD). X-ray diffraction pattern (XRD) and transmission electron diffraction pattern (TED) showed that NN-0.10BT thin film was epitaxially grown on SRO/(001)STO substrate with a crystallographic relationship of [001] NN-xBT parallel [001] STO . From reciprocal space maps, the lattice parameters of the out-of-plane direction of NN-xBT thin films became larger with an increase in BT concentration, although the lattice parameter of the in-plane was hardly changed by the BT concentration. The value of relative dielectric constant ε r of the NN-xBT thin films were increased with BT concentration. The ε r and the dielectric loss tanδ of NN-0.10BT were 1220 and 0.02 at 1 kHz, respectively. The P-E hysteresis loops of the NN-xBT thin films showed clear ferroelectricity. Although the value of remanent polarization P r decreased with the BT concentration, the behaviors of ε r , P r , and coercive electric field E c of the NN-xBT thin films against the BT concentration accorded with those of NN-xBT ceramics, in which NN-0.10BT ceramics exhibited the largest piezoelectric property. Therefore, the NN-0.10BT thin film is expected to show high piezoelectricity. (author)

  5. Comparison of residual stress measurement in thin films using surface micromachining method

    International Nuclear Information System (INIS)

    He, Q.; Luo, Z.X.; Chen, X.Y.

    2008-01-01

    Conductive, dielectric, semiconducting, piezoelectric and ferroelectric thin films are extensively used for MEMS/NEMS applications. One of the important parameters of thin films is residual stress. The residual stress can seriously affect the properties, performance and long-term stability of the films. Excessive compressive or tensile stress results in buckling, cracking, splintering and sticking problems. Stress measurement techniques are therefore essential for both process development and process monitoring. Many suggestions for stress measurement in thin films have been made over the past several decades. This paper is concentrated on the in situ stress measurement using surface micromachining techniques to determine the residual stress. The authors review and compare several types of stress measurement methods including buckling technique, rotating technique, micro strain gauge and long-short beam strain sensor

  6. Ferroelectricity in undoped hafnium oxide

    International Nuclear Information System (INIS)

    Polakowski, Patrick; Müller, Johannes

    2015-01-01

    We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4–20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization P r of up to 10 μC cm −2 as well as a read/write endurance of 1.6 × 10 5 cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems

  7. Ferroelectric properties of bilayer structured Pb(Zr0.52Ti0.48)O3/SrBi2Ta2O9 (PZT/SBT) thin films on Pt/TiO2/SiO2/Si substrates

    International Nuclear Information System (INIS)

    Zhang Wenqi; Li Aidong; Shao Qiyue; Xia Yidong; Wu Di; Liu Zhiguo; Ming Naiben

    2008-01-01

    Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films with large remanent polarization and SrBi 2 Ta 2 O 9 (SBT) thin films with excellent fatigue-resisting characteristic have been widely studied for non-volatile random access memories, respectively. To combine these two advantages , bilayered Pb(Zr 0.52 Ti 0.48 )O 3 /SrBi 2 Ta 2 O 9 (PZT/SBT) thin films were fabricated on Pt/TiO 2 /SiO 2 /Si substrates by chemical solution deposition method. X-ray diffraction patterns revealed that the diffraction peaks of PZT/SBT thin films were completely composed of PZT and SBT, and no other secondary phase was observed. The electrical properties of the bilayered structure PZT/SBT films have been investigated in comparison with pure PZT and SBT films. PZT/SBT bilayered thin films showed larger remanent polarization (2P r ) of 18.37 μC/cm 2 than pure SBT and less polarization fatigue up to 1 x 10 9 switching cycles than pure PZT. These results indicated that this bilayered structure of PZT/SBT is a promising material combination for ferroelectric memory applications

  8. Giant quadratic electro-optical effect during polarization switching in ultrathin ferroelectric polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Blinov, L. M., E-mail: lev39blinov@gmail.com; Lazarev, V V; Palto, S P; Yudin, S G [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2012-04-15

    The low-frequency quadratic electro-optical effect with a maximum electro-optical coefficient of g = 8 Multiplication-Sign 10{sup -19} m{sup 2}/V{sup 2} (i.e., four orders of magnitude greater than the standard high-frequency value) has been studied in thin films of ferroelectric polymer PVDF(70%)-TrFE(30%). The observed effect is related to the process of spontaneous polarization switching, during which the electron oscillators of C-F and C-H dipole groups rotate to become parallel to the applied field. As a result, the ellipsoid of the refractive index exhibits narrowing in the direction perpendicular to the field. The field dependence of the electro-optical coefficient g correlates with that of the apparent dielectric permittivity, which can be introduced under the condition of ferroelectric polarization switching. The observed electro-optical effect strongly decreases when the frequency increases up to several hundred hertz. The temperature dependence of the effect exhibits clearly pronounced hysteresis in the region of the ferroelectric phase transition.

  9. Phase and electrical properties of PZT thin films embedded with CuO nano-particles by a hybrid sol-gel route

    Science.gov (United States)

    Sreesattabud, Tharathip; Gibbons, Brady J.; Watcharapasorn, Anucha; Jiansirisomboon, Sukanda

    2013-07-01

    Pb(Zr0.52Ti0.48)O3 or PZT thin films embedded with CuO nano-particles were successfully prepared by a hybrid sol-gel process. In this process, CuO (0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 wt. %) nanopowder was suspended in an organometallic solution of PZT, and then coated on platinised silicon substrate using a spin-coating technique. The influence of CuO nano-particles' dispersion on the phase of PZT thin films was investigated. XRD results showed a perovskite phase in all films. At the CuO concentration of 0.4-1 wt. %, a second phase was observed. The addition of CuO nano-particles affected the orientation of PZT thin films. The addition was also found to reduce the ferroelectric properties of PZT thin films. However, at 0.2 wt. % CuO concentration, the film exhibited good ferroelectric properties similar to those of PZT films. In addition, the fatigue retention properties of the PZT/CuO system was observed, and it showed 14% fatigue at 108 switching bipolar pulse cycles while the fatigue in PZT thin films was found to be 17% at the same switching bipolar pulse cycles.

  10. Ferroelectricity and Piezoelectricity in Free-Standing Polycrystalline Films of Plastic Crystals.

    Science.gov (United States)

    Harada, Jun; Yoneyama, Naho; Yokokura, Seiya; Takahashi, Yukihiro; Miura, Atsushi; Kitamura, Noboru; Inabe, Tamotsu

    2018-01-10

    Plastic crystals represent a unique compound class that is often encountered in molecules with globular structures. The highly symmetric cubic crystal structure of plastic crystals endows these materials with multiaxial ferroelectricity that allows a three-dimensional realignment of the polarization axes of the crystals, which cannot be achieved using conventional molecular ferroelectric crystals with low crystal symmetry. In this work, we focused our attention on malleability as another characteristic feature of plastic crystals. We have synthesized the new plastic/ferroelectric ionic crystals tetramethylammonium tetrachloroferrate(III) and tetramethylammonium bromotrichloroferrate(III), and discovered that free-standing translucent films can be easily prepared by pressing powdered samples of these compounds. The thus obtained polycrystalline films exhibit ferroelectric polarization switching and a relatively large piezoelectric response at room temperature. The ready availability of functional films demonstrates the practical utility of such plastic/ferroelectric crystals, and considering the vast variety of possible constituent cations and anions, a wide range of applications should be expected for these unique and attractive functional materials.

  11. Electrostatic micromotor based on ferroelectric ceramics

    Science.gov (United States)

    Baginsky, I. L.; Kostsov, E. G.

    2004-11-01

    A new electrostatic micromotor is described that utilizes the electromechanical energy conversion principle earlier described by the authors. The electromechanical energy conversion is based on reversible electrostatic rolling of thin metallic films (petals) on a ferroelectric surface. The motor's active media are layers of ferroelectric ceramics (about 100 µm in thickness). The characteristics of the electrostatic rolling of the petals on different ceramic surfaces are studied, as well as the dynamic characteristics of the micromotors. It is shown that the use of antiferroelectric material allows one to reach a specific energy capacitance comparable to that of the micromotors based on ferroelectric films and to achieve a specific power of 30-300 µW mm-2.

  12. Enhanced magnetoelectric coupling in a composite multiferroic system via interposing a thin film polymer

    Science.gov (United States)

    Xiao, Zhuyun; Mohanchandra, Kotekar P.; Lo Conte, Roberto; Ty Karaba, C.; Schneider, J. D.; Chavez, Andres; Tiwari, Sidhant; Sohn, Hyunmin; Nowakowski, Mark E.; Scholl, Andreas; Tolbert, Sarah H.; Bokor, Jeffrey; Carman, Gregory P.; Candler, Rob N.

    2018-05-01

    Enhancing the magnetoelectric coupling in a strain-mediated multiferroic composite structure plays a vital role in controlling magnetism by electric fields. An enhancement of magnetoelastic coupling between ferroelectric single crystal (011)-cut [Pb(Mg1/3Nb2/3)O3](1-x)-[PbTiO3]x (PMN-PT, x≈ 0.30) and ferromagnetic polycrystalline Ni thin film through an interposed benzocyclobutene polymer thin film is reported. A nearly twofold increase in sensitivity of remanent magnetization in the Ni thin film to an applied electric field is observed. This observation suggests a viable method of improving the magnetoelectric response in these composite multiferroic systems.

  13. Effects of oxygen partial pressure on the ferroelectric properties of pulsed laser deposited Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Silva, J.P.B.; Sekhar, K.C.; Pereira, M.; Gomes, M.J.M. [University of Minho, Centre of Physics, Braga (Portugal); Almeida, A.; Agostinho Moreira, J. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Fisica e Astronomia, Faculdade de Ciencias da Universidade do Porto, Porto (Portugal)

    2013-11-15

    The Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} thin films were grown on the Pt-Si substrate at 700 C by using a pulsed laser deposition technique at different oxygen partial pressure (PO{sub 2}) in the range of 1-20 Pa and their properties were investigated. It is observed that the PO{sub 2} during the deposition plays an important role on the tetragonal distortion ratio, surface morphology, dielectric permittivity, ferroelectric polarization, switching response, and leakage currents of the films. With an increase in PO{sub 2}, the in-plane strain for the BST films changes from tensile to compressive. The films grown at 7.5 Pa show the optimum dielectric and ferroelectric properties and also exhibit the good polarization stability. It is assumed that a reasonable compressive strain, increasing the ionic displacement, and thus promotes the in-plane polarization in the field direction, could improve the dielectric permittivity. The butterfly features of the capacitance-voltage (C-V) characteristics and the bell shape curve in polarization current were attributed to the domain reversal process. The effect of pulse amplitude on the polarization reversal behavior of the BST films grown at PO{sub 2} of 7.5 Pa was studied. The peak value of the polarization current shows exponential dependence on the electric field. (orig.)

  14. Room temperature multiferroic properties of (Fe{sub x}, Sr{sub 1−x})TiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung-Tae; Kim, Cheolbok; Fang, Sheng-Po; Yoon, Yong-Kyu, E-mail: ykyoon@ece.ufl.edu [Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-09-08

    This letter reports the structural, dielectric, ferroelectric, and magnetic properties of Fe substituted SrTiO{sub 3} thin films in room temperature. The structural data obtained from x-ray diffraction indicates that (Fe{sub x},Sr{sub 1−x})TiO{sub 3}, the so called FST, transforms from pseudocubic to tetragonal structures with increase of the Fe content in SrTiO{sub 3} thin films, featuring the ferroelectricity, while vibrating sample magnetometer measurements show magnetic hysteresis loops for the samples with low iron contents indicating their ferromagnetism. The characterized ferroelectricity and ferromagnetism confirms strong multiferroitism of the single phase FST thin films in room temperature. Also, an FST thin film metal-insulator-metal multiferroic capacitor has been fabricated and characterized in microwave frequencies between 10 MHz and 5 GHz. A capacitor based on Fe{sub 0.1}Sr{sub 0.9}TiO{sub 3} with a thickness of 260 nm shows a high electric tunability of 18.6% at 10 V and a maximum magnetodielectric value of 1.37% at 0.4 mT with a loss tangent of 0.021 at 1 GHz. This high tuning and low loss makes this material as a good candidate for frequency agile microwave devices such as tunable filters, phase shifters, and antennas.

  15. Multiscale numerical study on ferroelectric nonlinear response of PZT thin films (Conference Presentation)

    Science.gov (United States)

    Wakabayashi, Hiroki; Uetsuji, Yasutomo; Tsuchiya, Kazuyoshi

    2017-06-01

    PZT thin films have excellent performance in deformation precision and response speed, so it is used widely for actuators and sensors of Micro Electro Mechanical System (MEMS). Although PZT thin films outputs large piezoelectricity at morphotropic phase bounfary (MPB), it shows a complicated hysteresis behavior caused by domain switching and structural phase transition between tetragonal and rhombohedral. In general, PZT thin films have some characteristic crystal morphologies. Additionally mechanical strains occur by lattice mismatch with substrate. Therefore it is important for fabrication and performance improvement of PZT thin films to understand the relation between macroscopic hysteresis response and microstructural changes. In this study, a multiscale nonlinear finite element simulation was proposed for PZT thin films at morphotropic phase boundary (MPB) on the substrate. The homogenization theory was employed for scale-bridging between macrostructure and microstructure. Figure 1 shows the proposed multiscale nonlinear simulation [1-3] based on the homogenization theory. Macrostructure is a homogeneous structure to catch the whole behaviors of actuators and sensors. And microstructure is a periodic inhomogeneous structure consisting of domains and grains. Macrostructure and microstructure are connected perfectly by homogenization theory and are analyzed by finite element method. We utilized an incremental form of fundamental constitutive law in consideration with physical property change caused by domain switching and structural phase transition. The developed multiscale finite element method was applied to PZT thin films with lattice mismatch strain on the substrate, and the relation between the macroscopic hysteresis response and microscopic domain switching and structural phase transition were investigated. Especially, we discuss about the effect of crystal morphologies and lattice mismatch strain on hysteresis response.

  16. Dielectric and piezoelectric properties of lead-free (Bi,Na)TiO3-based thin films

    Science.gov (United States)

    Abazari, M.; Safari, A.; Bharadwaja, S. S. N.; Trolier-McKinstry, S.

    2010-02-01

    Dielectric and piezoelectric properties of morphotropic phase boundary (Bi,Na)TiO3-(Bi,K)TiO3-BaTiO3 epitaxial thin films deposited on SrRuO3 coated SrTiO3 substrates were reported. Thin films of 350 nm thickness exhibited small signal dielectric permittivity and loss tangent values of 750 and 0.15, respectively, at 1 kHz. Ferroelectric hysteresis measurements indicated a remanent polarization value of 30 μC/cm2 with a coercive field of 85-100 kV/cm. The thin film transverse piezoelectric coefficient (e31,f) of these films after poling at 600 kV/cm was found to be -2.2 C/m2. The results indicate that these BNT-based thin films are a potential candidate for lead-free piezoelectric devices.

  17. Temperature dependence of electronic transport property in ferroelectric polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.L.; Wang, J.L., E-mail: jlwang@mail.sitp.ac.cn; Tian, B.B.; Liu, B.L.; Zou, Y.H.; Wang, X.D.; Sun, S.; Sun, J.L., E-mail: jlsun@mail.sitp.ac.cn; Meng, X.J.; Chu, J.H.

    2014-10-15

    Highlights: • The ferroelectric polymer was fabricated by Langmuir–Blodgett method. • The electrons as the dominant injected carrier were conformed in the ferroelectric polymer films. • The leakage current conduction mechanisms in ferroelectric polymer were investigated. - Abstract: The leakage current mechanism of ferroelectric copolymer of polyvinylidene fluoride with trifluoroethylene prepared by Langmuir–Blodgett was investigated in the temperature range from 100 K to 350 K. The electron as the dominant injected carrier was observed in the ferroelectric copolymer films. The transport mechanisms in copolymer strongly depend on the temperature and applied voltage. From 100 K to 200 K, Schottky emission dominates the conduction. With temperature increasing, the Frenkel–Poole emission instead of the Schottky emission to conduct the carrier transport. When the temperature gets to 260 K, the leakage current becomes independent of temperature, and the space charge limited current conduction was observed.

  18. Structure and properties of PZT thin films on strontium ruthenate and calcium ruthenate electrodes

    International Nuclear Information System (INIS)

    Wu, T.-J.; Tsai, D.-S.

    2004-01-01

    PZT thin films have been prepared via metalorganic CVD (MOCVD) on four substrates of conducting oxides of ruthenates, SrRuO 3 /Pt/Ti/SiO 2 /Si(1 0 0), SrRuO 3 /SiO 2 /Si(1 0 0), CaRuO 3 /Pt/Ti/SiO 2 /Si(1 0 0), CaRuO 3 /SiO 2 /Si(1 0 0). The conducting ruthenate layers were also grown using MOCVD. Ferroelectric properties of polarization fatigue and leakage current density are measured. The internal strain of PZT thin crystal which is mainly constrained by the bottom electrode seems to be the decisive factor in ferroelectric properties. The internal strain of PZT is represented by its tetragonality ratio. The PZT thin film in the capacitor Au/PZT/SrRuO 3 /Pt/Ti/SiO 2 /Si, with the largest tetragonality ratio 1.026, exhibits an optimum combination of large polarization, less fatigue, and low leakage current density. Both SrRuO 3 and CaRuO 3 are good diffusion barriers to prevent interdiffusion of cations between the ferroelectric and the electrode. The slightly higher intermixing at the CaRuO 3 -to-Pt/Ti interface is owing to the high annealing temperature needed in CaRuO 3 synthesis

  19. Structure-Function Relationships of Ferroelectric Polymers.

    Science.gov (United States)

    Pavlopoulou, Eleni; Maiz, Jon; Spampinato, Nicoletta; Maglione, Mario; Hadziioannou, Georges

    Poly(vinylidene fluoride), PVDF, and its copolymers with trifluoroethylene, P(VDF-co-TrFE) have been long appreciated for their excellent ferroelectric properties. Although they have been mainly studied in the 80s and 90s, understanding their performance is still lacking. Yet the increasing use of P(VDF-co-TrFE) thin films in organic electronic devices during the last ten years revives the need for apprehending the function of these materials. In this work we investigate the structure of P(VDF-co-TrFE) films and correlate it to their ferroelectric properties. Our results show that ferroelectric performance is solely driven by the fraction of polymer that has been crystallized in the ferroelectric phases of PVDF. The relations between remnant polarization, coercive field and dipole switching rate of P(VDF-co-TrFE) with the ferroelectric crystallinity are demonstrated. The French Research Agency (ANR), the Aquitaine Region, Arkema and STMicroelectronics are kindly acknowledged for financial support.

  20. Multiferroic BiFeO3 thin films and nanodots grown on highly oriented pyrolytic graphite substrates

    Science.gov (United States)

    Shin, Hyun Wook; Son, Jong Yeog

    2017-12-01

    Multiferroic BiFeO3 (BFO) thin films and nanodots are deposited on highly oriented pyrolytic graphite (HOPG) substrates via a pulsed laser deposition technique, where the HOPG surface has a honeycomb lattice structure made of carbon atoms, similar to graphene. A graphene/BFO/HOPG capacitor exhibited multiferroic properties, namely ferroelectricity (a residual polarization of 26.8 μC/cm2) and ferromagnetism (a residual magnetization of 1.1 × 10-5 emu). The BFO thin film had high domain wall energies and demonstrated switching time of approximately 82 ns. An 8-nm BFO nanodot showed a typical piezoelectric hysteresis loop with an effective residual piezoelectric constant of approximately 110 pm/V and exhibited two clearly separated current curves depending on the ferroelectric polarization direction.

  1. Epitaxial Bi2 FeCrO6 Multiferroic Thin Film as a New Visible Light Absorbing Photocathode Material.

    Science.gov (United States)

    Li, Shun; AlOtaibi, Bandar; Huang, Wei; Mi, Zetian; Serpone, Nick; Nechache, Riad; Rosei, Federico

    2015-08-26

    Ferroelectric materials have been studied increasingly for solar energy conversion technologies due to the efficient charge separation driven by the polarization induced internal electric field. However, their insufficient conversion efficiency is still a major challenge. Here, a photocathode material of epitaxial double perovskite Bi(2) FeCrO(6) multiferroic thin film is reported with a suitable conduction band position and small bandgap (1.9-2.1 eV), for visible-light-driven reduction of water to hydrogen. Photoelectrochemical measurements show that the highest photocurrent density up to -1.02 mA cm(-2) at a potential of -0.97 V versus reversible hydrogen electrode is obtained in p-type Bi(2) FeCrO(6) thin film photocathode grown on SrTiO(3) substrate under AM 1.5G simulated sunlight. In addition, a twofold enhancement of photocurrent density is obtained after negatively poling the Bi(2) FeCrO(6) thin film, as a result of modulation of the band structure by suitable control of the internal electric field gradient originating from the ferroelectric polarization in the Bi(2) FeCrO(6) films. The findings validate the use of multiferroic Bi(2) FeCrO(6) thin films as photocathode materials, and also prove that the manipulation of internal fields through polarization in ferroelectric materials is a promising strategy for the design of improved photoelectrodes and smart devices for solar energy conversion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Preparation of Pb(Zr, Ti)O3 Thin Films on Glass Substrates

    Science.gov (United States)

    Hioki, Tsuyoshi; Akiyama, Masahiko; Ueda, Tomomasa; Onozuka, Yutaka; Hara, Yujiro; Suzuki, Kouji

    2000-09-01

    Lead-zirconate-titanate (PZT) thin films were prepared on non-alkaline glass substrates widely used in liquid crystal display (LCD) devices, by plasma-assisted magnetron RF sputtering with an immersed coil. After preparation of the PZT thin film, the glass was available for use in LCD device processing. No mutual diffusion of the elements was recognized between the glass substrate and the bottom electrode. The PZT layer had a dense film structure with rectangular and columnar grains, and only its perovskite phase was crystalline. PZT thin films on a glass substrate had leakage current densities of about 10-8 A/cm2, acceptable hysteresis loop shapes with the remanent polarization (Pr) of 45 μC/cm2 and the coercive field (Ec) of 90 kV/cm. Ferroelectric properties on a glass substrate almost conform with those on a Si-based substrate.

  3. Nonlinear current-voltage behavior in PZT thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Mi; Zhang, Weikang; Zhang, Zebin; Li, Shida; Zhang, Ping; Lan, Kuibo [Tianjin University, School of Electrical and Information Engineering, Tianjin (China)

    2017-05-15

    In this paper, Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) thin films were prepared by sol-gel synthesis and characterized by X-ray diffraction, field emission scanning electron microscopy and current-voltage measurements. Here, we demonstrate that in addition to the outstanding ferroelectric and dielectric properties, the PZT films also have remarkably nonlinear current-voltage characteristics. Considering the contact of semi-conductive grains in the PZT films, a double Schottky barrier (DSB) model may be responsible for such phenomena. The test results show that with the decrease of annealing temperature and the increase of the film thickness, the threshold voltages (V{sub th}) increase obviously. The maximum V{sub th} value of 60.95 V and the minimum value of 6.9 V in our experiments were obtained from the five-layered samples annealed at 600 C and the two-layered samples annealed at 700 C, respectively. As a result, PZT thin film may lead to efficient switching and sensing devices. (orig.)

  4. Suppression of slow capacitance relaxation phenomenon in Pt/Ba0.3Sr0.7TiO3/Pt thin film ferroelectric structures by annealing in oxygen atmosphere

    KAUST Repository

    Altynnikov, A. G.

    2014-01-27

    The impact of oxygen annealing on the switching time of ferroelectric thin film capacitor structures Pt/Ba0.3Sr0.7TiO3/Pt was investigated. The response of their capacitance on pulsed control voltages before and after annealing was experimentally measured. It was demonstrated that the annealing results in suppression of the capacitance slow relaxation processes and increase of the threshold control voltages. These structures can therefore be attractive for fabrication of fast acting microwave devices. © 2014 Author(s).

  5. Universal ferroelectric switching dynamics of vinylidene fluoride-trifluoroethylene copolymer films

    KAUST Repository

    Hu, Weijin

    2014-04-24

    In this work, switching dynamics of poly(vinylidene fluoride- trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50 ...MV/m and 180 domain wall energy of 60 ...mJ/m 2 are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications.

  6. Universal ferroelectric switching dynamics of vinylidene fluoride-trifluoroethylene copolymer films

    KAUST Repository

    Hu, Weijin; Juo, Deng-Ming; You, Lu; Wang, Junling; Chen, Yi-Chun; Chu, Ying-Hao; Wu, Tao

    2014-01-01

    In this work, switching dynamics of poly(vinylidene fluoride- trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50 ...MV/m and 180 domain wall energy of 60 ...mJ/m 2 are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications.

  7. Thickness-dependent a_1/a_2 domain evolution in ferroelectric PbTiO_3 films

    International Nuclear Information System (INIS)

    Li, S.; Zhu, Y.L.; Tang, Y.L.; Liu, Y.; Zhang, S.R.; Wang, Y.J.; Ma, X.L.

    2017-01-01

    Ferroelectric a_1/a_2 domain structure has great potentials in high dielectric capacitors and tunable microwave devices. Understanding its structure is crucial to better control the domain configurations for future applications. In this paper, PbTiO_3 thin films with variant thicknesses are deposited on (110)-oriented GdScO_3 substrates by Pulsed Laser Deposition (PLD) and investigated by using conventional transmission electron microscopy (TEM) and Cs-corrected Scanning TEM. Contrast analysis and electron diffractions reveal that PbTiO_3 films are domain oriented consisting of a_1/a_2 and a/c domain structure. The a_1/a_2 domains are found to distribute periodically and its width increases with increasing film thickness following square root rule. Cs-corrected STEM imaging demonstrates that the domain walls of a_1/a_2 domain structure have the rotation characteristic of 90° ferroelastic domain wall. The interchange of a_1/a_2 domains induces the formation of vertex domains composed of two 90° and one 180° domain walls. Strains are mainly concentrated on the domain walls. The formation of this complex domain configuration is discussed in terms of the effect of the misfit strain, film thickness and cooling rate. These results provide novel information about a_1/a_2 domain structures and are expected to shed some light on modulating a_1/a_2 ferroelectric domain patterns in the design of ferroelectric-based devices.

  8. Improvement of the fatigue and the ferroelectric properties of PZT films through a LSCO seed layer

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Sofia A.S., E-mail: sofiarodrigues@fisica.uminho.pt; Silva, José P.B.; Khodorov, Anatoli; Martín-Sánchez, Javier; Pereira, M.; Gomes, M.J.M.

    2013-11-01

    Highlights: • Pulsed laser deposited PZT thin films. • Seed layer effect on the structural and ferroelectric properties of the PZT films. • The stability of P{sub r} was improved with the introduction of the LSCO layer. -- Abstract: The ability to optimizate the preparation of Lead Zirconate Titanate (PZT) films on platinized Si substrate by pulsed laser deposition was demonstrated. The effect of the modification of the interface film/electrode through the use of a (La,Sr)CoO{sub 3} (LSCO) seed layer on the remnant polarization, fatigue endurance and stress in PZT films was studied. An improvement on the ferroelectric properties was found with the using of the LSCO layer. A remnant polarization (P{sub r}) of 19.8 μC/cm{sup 2} and 4.4 μC/cm{sup 2} for films with and without the LSCO layer were found. In the same way the polarization fatigue decreases significantly after deposition of the LSCO layer between the film and substrate. Atomic force microscopy (AFM) images revealed a different growth process in the films. Current–voltage (I–V) measurements showed that the use of LSCO seed layer improves the leakage current and, on the other hand the conduction mechanisms in the film without LSCO, after the fatigue test, was found to be changed from Schottky to Poole–Frenkel. The trap activation energy (about 0.14 eV) determined from Poole–Frenkel mode agrees well with the energy level of oxygen vacancies. The films stresses were estimated by XRD in order to explain the improvement on the structure and consequentially ferroelectric properties of the films. The model proposed by Dawber and Scott was found to be in agreement with our experimental data, which seems to predict that the oxygen vacancies play an important role on fatigue.

  9. Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film

    International Nuclear Information System (INIS)

    Gupta, Surbhi; Gupta, Vinay; Tomar, Monika; James, A. R.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar

    2014-01-01

    Multiferroic Bismuth Ferrite (BiFeO 3 ) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO 3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO 3 and Fe 2 O 3 to pure BiFeO 3 phase and, subsequently, to a mixture of BiFeO 3 and Bi 2 O 3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO 3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe 2 O 3 ). Deterioration in ferroic properties of BiFeO 3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO 3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm 2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO 3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO 3 thin films exhibiting the improved multiferroic properties.

  10. Ferroelectric and piezoelectric properties of lead-free BaTiO{sub 3} doped Bi{sub 0.5}Na{sub 0.5}TiO{sub 3} thin films from metal-organic solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, Susant Kumar [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Lee, Sang-Kwon; Hyung, Jung-Hwan [Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Yang, Yun-Ho; Kim, Bok-Hee [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Ahn, Byung-Guk, E-mail: bkahn@jbnu.ac.kr [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2012-11-05

    Highlights: Black-Right-Pointing-Pointer Lead-free BNT-BT thin films from an optimized metal-organic solution deposition. Black-Right-Pointing-Pointer Phase and microstructure evolution with annealing temperature. Black-Right-Pointing-Pointer A relatively low leakage current density. Black-Right-Pointing-Pointer Good dielectric constant of 613 at a frequency of 1 kHz. Black-Right-Pointing-Pointer High remanent polarization and piezoelectric constant comparable to PZT thin films. - Abstract: Lead-free 0.94Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.06BaTiO{sub 3} (BNT-BT) piezoelectric thin films were prepared by metal-organic solution deposition onto a Pt/Ti/SiO{sub 2}/Si substrate. A dense and well crystallized thin film with a perovskite phase was obtained by annealing these films at 700 Degree-Sign C. Atomic force microscopy showed that these films were smooth and crack-free with an average grain size on the order of 200 nm. Thin films of 356 nm thickness exhibited a small signal dielectric constant and a loss tangent at 1 kHz of 613 and 0.044, respectively. Ferroelectric hysteresis measurements indicated a remanent polarization value of 21.5 {mu}C/cm{sup 2} with a coercive field of 164.5 kV/cm. The leakage current density of the thin film was 4.08 Multiplication-Sign 10{sup -4} A/cm{sup 2} at an applied electric field of 200 kV/cm. A typical butterfly-shaped piezoresponse loop was observed and the effective piezoelectric coefficient (d{sub 33}) of the BNT-BT thin film was approximately 51.6 pm/V.

  11. Comparison of lead zirconate titanate thin films on ruthenium oxide and platinum electrodes

    OpenAIRE

    Bursill, Les A.; Reaney, Ian M.; Vijay, Dilip P.; Desu, Seshu B.

    1994-01-01

    High-resolution and bright- and dark-field transmission electron microscopy are used to characterize and compare the interface structures and microstructure of PZT/RuO2/SiO2/Si and PZT/Pt/Ti/SiO2/Si ferroelectric thin films, with a view to understanding the improved fatigue characteristics of PZT thin films with RuO2 electrodes. The RuO2/PZT interface consists of a curved pseudoperiodic minimal surface. The interface is chemically sharp with virtually no intermixing of RuO2 and PZT, as eviden...

  12. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    Energy Technology Data Exchange (ETDEWEB)

    Daranciang, Dan

    2012-02-15

    We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  13. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    International Nuclear Information System (INIS)

    Daranciang, Dan

    2012-01-01

    We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  14. Ferroelectric capped magnetization in multiferroic PZT/LSMO tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ashok, E-mail: ashok553@nplindia.org; Shukla, A. K. [National Physical Laboratory (CSIR), Dr. K. S. Krishnan Road, New Delhi-110012 (India); Barrionuevo, D.; Ortega, N.; Katiyar, Ram S. [Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931-3343 (United States); Shannigrahi, Santiranjan [Institute of Materials Research and Engineering - IMRE, Agency for Science Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); Scott, J. F. [Department of Chemistry and Department of Physics, University of St. Andrews, St. Andrews KY16 ST (United Kingdom)

    2015-03-30

    Self-poled ultra-thin ferroelectric PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} (PZT) (5 and 7 nm) films have been grown by pulsed laser deposition technique on ferromagnetic La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) (30 nm) to check the effect of polar capping on magnetization for ferroelectric tunnel junction devices. PZT/LSMO heterostructures with thick polar PZT (7 nm) capping show nearly 100% enhancement in magnetization compared with thin polar PZT (5 nm) films, probably due to excess hole transfer from the ferroelectric to the ferromagnetic layers. Core-level x-ray photoelectron spectroscopy studies revealed the presence of larger Mn 3s exchange splitting and higher Mn{sup 3+}/Mn{sup 4+} ion ratio in the LSMO with 7 nm polar capping.

  15. Tunable multiband ferroelectric devices for reconfigurable RF-frontends

    CERN Document Server

    Zheng, Yuliang

    2013-01-01

    Reconfigurable RF-frontends aim to cope with the continuous pursuit of wider frequency coverage, higher efficiency, further compactness and lower cost of ownership. They are expected to lay the foundations of future software defined or cognitive radios. As a potential enabling technology for the frontends, the tunable ferroelectric devices have shown not only enhanced performance but also new functionalities. This book explores the recent developments in the field. It provides a cross-sectional perspective on the interdisciplinary research. With attention to the devices based on ceramic thick-films and crystal thin-films, the book reviews the adapted technologies of material synthesis, film deposition and multilayer circuitry. Next, it highlights the original classes of thin-film ferroelectric devices, including stratified metal-insulator-metal varactors with suppression of acoustic resonance and programmable bi-stable high frequency capacitors. At the end the book analyzes how the frontends can be reformed b...

  16. High temperature phases in PZT ferroelectric films

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Suchaneck, G.; Jastrabík, Lubomír; Gerlach, G.

    2003-01-01

    Roč. 293, - (2003), s. 111-118 ISSN 0015-0193 R&D Projects: GA ČR GP202/02/D078; GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferroelectric film * phase transition * film profile Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.406, year: 2003

  17. Hierarchy and scaling behavior of multi-rank domain patterns in ferroelectric K0.9Na0.1NbO3 strained films

    Science.gov (United States)

    Braun, Dorothee; Schmidbauer, Martin; Hanke, Michael; Schwarzkopf, Jutta

    2018-01-01

    The formation process of a ferroelectric multi-rank domain pattern in the thickness range of 7-52 nm is investigated for monoclinic K0.9Na0.1NbO3 strained epitaxial films on (110) NdScO3 substrates. Although the elastic strain energy density is degenerated for two pseudocubic orientations, a distinctive hierarchy of domain evolution is observed with exclusive in-plane a1a2 domains for very thin films and the retarded onset of a ferroelectric MC phase at larger film thickness. This is accompanied by a thickness dependent transformation from stripe domains to a herringbone pattern and, eventually, for the thickest film, to a checkerboard-like structure. These transformations in the domain arrangement and width are correlated to energetic aspects as depolarization field and anisotropic strain relaxation in the film. While for the MC domains plastic strain relaxation is throughout observed, the a1a2 domains show a two-step strain relaxation mechanism starting with an in-plane elastic shearing, which is followed by plastic lattice relaxation. Our results highlight a pathway for engineering and patterning of periodic ferroelectric domain structures.

  18. Photovoltaic effect in transition metal modified polycrystalline BiFeO3 thin films

    International Nuclear Information System (INIS)

    Puli, Venkata Sreenivas; Chrisey, Douglas B; Pradhan, Dhiren Kumar; Katiyar, Rajesh Kumar; Misra, Pankaj; Scott, J F; Katiyar, Ram S; Coondoo, Indrani; Panwar, Neeraj

    2014-01-01

    We report photovoltaic (PV) effect in multiferroic Bi 0.9 Sm 0.1 Fe 0.95 Co 0.05 O 3 (BSFCO) thin films. Transition metal modified polycrystalline BiFeO 3 (BFO) thin films have been deposited on Pt/TiO 2 /SiO 2 /Si substrate successfully through pulsed laser deposition (PLD). PV response is observed under illumination both in sandwich and lateral electrode configurations. The open-circuit voltage (V oc ) and the short-circuit current density (J sc ) of the films in sandwich electrode configuration under illumination are measured to be 0.9 V and −0.051 µA cm −2 . Additionally, we report piezoresponse for BSFCO films, which confirms ferroelectric piezoelectric behaviour. (paper)

  19. Structural sensitivity of x-ray Bragg projection ptychography to domain patterns in epitaxial thin films

    International Nuclear Information System (INIS)

    Hruszkewycz, S. O.; Zhang, Q.; Holt, M. V.; Highland, M. J.

    2016-01-01

    Bragg projection ptychography (BPP) is a coherent diffraction imaging technique capable of mapping the spatial distribution of the Bragg structure factor in nanostructured thin films. Here, we show that, because these images are projections, the structural sensitivity of the resulting images depends on the film thickness and the aspect ratio and orientation of the features of interest and that image interpretation depends on these factors. Lastly, we model changes in contrast in the BPP reconstructions of simulated PbTiO_3 ferroelectric thin films with meandering 180° stripe domains as a function of film thickness, discuss their origin, and comment on the implication of these factors on the design of BPP experiments of general nanostructured films.

  20. Ferroelectric properties of Pb(Zr,Ti)O3 films under ion-beam induced strain

    Science.gov (United States)

    Lee, Jung-Kun; Nastasi, Michael

    2012-11-01

    The influence of an ion-beam induced biaxial stress on the ferroelectric and dielectric properties of Pb(Zr,Ti)O3 (PZT) films is investigated using the ion beam process as a novel approach to control external stress. Tensile stress is observed to decrease the polarization, permittivity, and ferroelectric fatigue resistance of the PZT films whose structure is monoclinic. However, a compressive stress increases all of them in monoclinic PZT films. The dependence of the permittivity on stress is found not to follow the phenomenological theory relating external forces to intrinsic properties of ferroelectric materials. Changes in the ferroelectric and dielectric properties indicate that the application of a biaxial stress modulates both extrinsic and intrinsic properties of PZT films. Different degrees of dielectric non-linearity suggests the density and mobility of non-180o domain walls, and the domain switching can be controlled by an applied biaxial stress and thereby influence the ferroelectric and dielectric properties.

  1. Structural, magnetic, and ferroelectric properties of T-like cobalt-doped BiFeO3 thin films

    Science.gov (United States)

    Young, T.; Sharma, P.; Kim, D. H.; Ha, Thai Duy; Juang, Jenh-Yih; Chu, Y.-H.; Seidel, J.; Nagarajan, V.; Yasui, S.; Itoh, M.; Sando, D.

    2018-02-01

    We present a comprehensive study of the physical properties of epitaxial cobalt-doped BiFeO3 films ˜50 nm thick grown on (001) LaAlO3 substrates. X-ray diffraction and magnetic characterization demonstrate high quality purely tetragonal-like (T') phase films with no parasitic impurities. Remarkably, the step-and-terrace film surface morphology can be fully recovered following a local electric-field-induced rhombohedral-like to T' phase transformation. Local switching spectroscopy experiments confirm the ferroelectric switching to follow previously reported transition pathways. Critically, we show unequivocal evidence for conduction at domain walls between polarization variants in T'-like BFO, making this material system an attractive candidate for domain wall-based nanoelectronics.

  2. Raman analysis of ferroelectric switching in niobium-doped lead zirconate titanate thin films

    International Nuclear Information System (INIS)

    Ferrari, P.; Ramos-Moore, E.; Guitar, M.A.; Cabrera, A.L.

    2014-01-01

    Characteristic Raman vibration modes of niobium-doped lead zirconate titanate (PNZT) are studied as a function of ferroelectric domain switching. The microstructure of PNZT is characterized by scanning electron microscopy and X-ray diffraction. Ferroelectric switching is achieved by applying voltages between the top (Au) and bottom (Pt) electrodes, while acquiring the Raman spectra in situ. Vibrational active modes associated with paraelectric and ferroelectric phases are identified after measuring above and below the ferroelectric Curie temperature, respectively. Changes in the relative intensities of the Raman peaks are observed as a function of the switching voltage. The peak area associated with the ferroelectric modes is analyzed as a function of the applied voltage within one ferroelectric polarization loop, showing local maxima around the coercive voltage. This behavior can be understood in terms of the correlation between vibrational and structural properties, since ferroelectric switching modifies the interaction between the body-centered atom (Zr, Ti or Nb) and the Pb–O lattice. - Highlights: • Electric fields induce structural distortions on ferroelectric perovskites. • Ferroelectric capacitor was fabricated to perform hysteresis loops. • Raman analysis was performed in situ during ferroelectric switching. • Raman modes show hysteresis and inflections around the coercive voltages. • Data can be understood in terms of vibrational–structural correlations

  3. Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO{sub 3} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Surbhi; Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi (India); Tomar, Monika [Department of Physics, Miranda Housea, University of Delhi, Delhi (India); James, A. R. [Defence Metallurgical Research Laboratory, Hyderabad (India); Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar [Department of Electrical and Computer Engineering, College of Engineering, University of Texas at SanAntonio, San Antonio 78249 (United States)

    2014-06-21

    Multiferroic Bismuth Ferrite (BiFeO{sub 3}) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO{sub 3} thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO{sub 3} and Fe{sub 2}O{sub 3} to pure BiFeO{sub 3} phase and, subsequently, to a mixture of BiFeO{sub 3} and Bi{sub 2}O{sub 3} with increase in the concentration of excess Bi from 0% to 15%. BiFeO{sub 3} thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe{sub 2}O{sub 3}). Deterioration in ferroic properties of BiFeO{sub 3} thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO{sub 3} thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm{sup 2} and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO{sub 3} thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO{sub 3} thin films exhibiting the improved multiferroic properties.

  4. Crystallization of sol-gel derived lead zirconate titanate thin films in argon and oxygen atmospheres

    International Nuclear Information System (INIS)

    Bursill, L.A.

    1994-01-01

    Electron diffraction and high-resolution electron microscopic techniques are applied to reveal the mechanisms of crystallization of 75 nm thin films of ferroelectric lead-zirconate-titanate (PZT). Sol-gel methods, followed by pyrolysis at 350 deg C, were used to provide a common starting point after which a variety of rapid-thermal annealing (RTA) experiments in the temperature range 400-700 deg C were made in argon, oxygen and nitrogen/hydrogen atmospheres. The results are interpreted in terms of the crystal chemical analysis, which points out that partial pressure of oxygen and heating rate are important experimental parameters which must be controlled if ferroelectric perovskite-type Pb 2 ZrTiO 6 , rather than pyrochlore-type Pb 2 ZrTiO 6+x , where O < X < 1 or -1 < X < O, is to be obtained after the RTA step. Thus significant improvements in the crystallization of perovskite-type PZT were clearly demonstrated by using argon atmospheres for the RTA step. The results have significance for the production of high-quality ferroelectric thin films, with improved switching and fatigue characteristics, since even small amounts of the pyrochlore phase prove detrimental for these properties. 18 refs., 1 tab., 10 figs

  5. Piezoelectricity and ferroelectricity of cellular polypropylene electrets films characterized by piezoresponse force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Hongchen; Sun, Yao; Zhou, Xilong; Li, Yingwei [LTCS and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); Li, Faxin, E-mail: lifaxin@pku.edu.cn [LTCS and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); HEDPS and Center for Applied Physics and Technology, Peking University, Beijing (China)

    2014-08-14

    Cellular electrets polymer is a new ferroelectret material exhibiting large piezoelectricity and has attracted considerable attentions in researches and industries. Property characterization is very important for this material and current investigations are mostly on macroscopic properties. In this work, we conduct nanoscale piezoelectric and ferroelectric characterizations of cellular polypropylene (PP) films using piezoresponse force microscopy (PFM). First, both the single-frequency PFM and dual-frequency resonance-tracking PFM testings were conducted on the cellular PP film. The localized piezoelectric constant d{sub 33} is estimated to be 7–11pC/N by correcting the resonance magnification with quality factor and it is about one order lower than the macroscopic value. Next, using the switching spectroscopy PFM (SS-PFM), we studied polarization switching behavior of the cellular PP films. Results show that it exhibits the typical ferroelectric-like phase hysteresis loops and butterfly-shaped amplitude loops, which is similar to that of a poly(vinylidene fluoride) (PVDF) ferroelectric polymer film. However, both the phase and amplitude loops of the PP film are intensively asymmetric, which is thought to be caused by the nonzero remnant polarization after poling. Then, the D-E hysteresis loops of both the cellular PP film and PVDF film were measured by using the same wave form as that used in the SS-PFM, and the results show significant differences. Finally, we suggest that the ferroelectric-like behavior of cellular electrets films should be distinguished from that of typical ferroelectrics, both macroscopically and microscopically.

  6. Effect of top electrode material on radiation-induced degradation of ferroelectric thin film structures

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, Steven J.; Bassiri-Gharb, Nazanin [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Deng, Carmen Z.; Callaway, Connor P. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Paul, McKinley K. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Woodward Academy, College Park, Georgia 30337 (United States); Fisher, Kenzie J. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Riverwood International Charter School, Atlanta, Georgia 30328 (United States); Guerrier, Jonathon E.; Jones, Jacob L. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Rudy, Ryan Q.; Polcawich, Ronald G. [Army Research Laboratory, Adelphi, Maryland 20783 (United States); Glaser, Evan R.; Cress, Cory D. [Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-07-14

    The effects of gamma irradiation on the dielectric and piezoelectric responses of Pb[Zr{sub 0.52}Ti{sub 0.48}]O{sub 3} (PZT) thin film stacks were investigated for structures with conductive oxide (IrO{sub 2}) and metallic (Pt) top electrodes. The samples showed, generally, degradation of various key dielectric, ferroelectric, and electromechanical responses when exposed to 2.5 Mrad (Si) {sup 60}Co gamma radiation. However, the low-field, relative dielectric permittivity, ε{sub r}, remained largely unaffected by irradiation in samples with both types of electrodes. Samples with Pt top electrodes showed substantial degradation of the remanent polarization and overall piezoelectric response, as well as pinching of the polarization hysteresis curves and creation of multiple peaks in the permittivity-electric field curves post irradiation. The samples with oxide electrodes, however, were largely impervious to the same radiation dose, with less than 5% change in any of the functional characteristics. The results suggest a radiation-induced change in the defect population or defect energy in PZT with metallic top electrodes, which substantially affects motion of internal interfaces such as domain walls. Additionally, the differences observed for stacks with different electrode materials implicate the ferroelectric–electrode interface as either the predominant source of radiation-induced effects (Pt electrodes) or the site of healing for radiation-induced defects (IrO{sub 2} electrodes).

  7. Electric and ferroelectric properties of PZT/BLT multilayer films prepared by photochemical metal-organic deposition

    Science.gov (United States)

    Park, Hyeong-Ho; Lee, Hong-Sub; Park, Hyung-Ho; Hill, Ross H.; Hwang, Yun Taek

    2009-01-01

    The electric and ferroelectric properties of lead zirconate titanate (PZT) and lanthanum-substituted bismuth titanate (BLT) multilayer films prepared using photosensitive precursors were characterized. The electric and ferroelectric properties were investigated by studying the effect of the stacking order of four ferroelectric layers of PZT or BLT in 4-PZT, PZT/2-BLT/PZT, BLT/2-PZT/BLT, and 4-BLT multilayer films. The remnant polarization values of the 4-BLT and BLT/2-PZT/BLT multilayer films were 12 and 17 μC/cm 2, respectively. Improved ferroelectric properties of the PZT/BLT multilayer films were obtained by using a PZT intermediate layer. The films which contained a BLT layer on the Pt substrate had improved leakage currents of approximately two orders of magnitude and enhanced fatigue resistances compared to the films with a PZT layer on the Pt substrate. These improvements are due to the reduced number of defects and space charges near the Pt electrodes. The PZT/BLT multilayer films prepared by photochemical metal-organic deposition (PMOD) possessed enhanced electric and ferroelectric properties, and allow direct patterning to fabricate micro-patterned systems without dry etching.

  8. Electric and ferroelectric properties of PZT/BLT multilayer films prepared by photochemical metal-organic deposition

    International Nuclear Information System (INIS)

    Park, Hyeong-Ho; Lee, Hong-Sub; Park, Hyung-Ho; Hill, Ross H.; Hwang, Yun Taek

    2009-01-01

    The electric and ferroelectric properties of lead zirconate titanate (PZT) and lanthanum-substituted bismuth titanate (BLT) multilayer films prepared using photosensitive precursors were characterized. The electric and ferroelectric properties were investigated by studying the effect of the stacking order of four ferroelectric layers of PZT or BLT in 4-PZT, PZT/2-BLT/PZT, BLT/2-PZT/BLT, and 4-BLT multilayer films. The remnant polarization values of the 4-BLT and BLT/2-PZT/BLT multilayer films were 12 and 17 μC/cm 2 , respectively. Improved ferroelectric properties of the PZT/BLT multilayer films were obtained by using a PZT intermediate layer. The films which contained a BLT layer on the Pt substrate had improved leakage currents of approximately two orders of magnitude and enhanced fatigue resistances compared to the films with a PZT layer on the Pt substrate. These improvements are due to the reduced number of defects and space charges near the Pt electrodes. The PZT/BLT multilayer films prepared by photochemical metal-organic deposition (PMOD) possessed enhanced electric and ferroelectric properties, and allow direct patterning to fabricate micro-patterned systems without dry etching.

  9. Structure and electrical properties of Pb(ZrxTi1-x)O3 deposited on textured Pt thin films

    International Nuclear Information System (INIS)

    Hong, Jongin; Song, Han Wook; Lee, Hee Chul; Lee, Won Jong; No, Kwangsoo

    2001-01-01

    The texturing of the bottom electrode plays a key role in the structure and electrical properties of Pb(Zr,Ti)O 3 (PZT) thin films. We fabricated Pt bottom electrodes having a different thickness on MgO single crystals at 600 o C by rf magnetron sputtering. As the thickness of platinum (Pt) thin film increased, the preferred orientation of Pt thin film changed from (200) to (111). PZT thin films were fabricated at 450 o C by electron cyclotron resonance-plasma enhanced metal organic chemical vapor deposition on the textured Pt thin films. The texturing of the bottom electrode caused drastic changes in the C--V characteristics, P--E characteristics, and fatigue characteristics of metal/ferroelectric material/metal (MFM) capacitors. The difference of the electrical properties between the PZT thin films having different texturing was discussed in terms-of the x--y alignment and the interface between electrode and PZT in MFM capacitors. copyright 2001 American Institute of Physics

  10. History and the future perspective of the ferroelectric memory; Kyoyudentai memory no rekishiteki haikei to tenbo

    Energy Technology Data Exchange (ETDEWEB)

    Tarui, Y [Waseda University, Tokyo (Japan)

    1998-10-01

    Development work is in progress on ferroelectric memory. The memory is a most suitable non-volatile memory which can be incorporated into IC cards, with its higher speed, lower voltage operation, smaller power consumption, and greater number of rewriting times than EEPROM, DRAM and SRAM. Taking as an opportunity the announcement on an experiment as performed by the authors to control semiconductor charge by using electric depolarization of ferroelectric materials, reports have been made one after another on experiments on thin metal films on TGS or BaTiO3, and experiments on semiconductor films formed on ferroelectric crystals or ceramics substrates by using vacuum deposition. In order to solve problems in ferroelectric materials, thin films of PZT and PLZT have emerged, whose good hysteresis characteristics have also been reported. Thereafter, an announcement was made on a material with bismuth layer like perovskite structure. The material is characterized with having very little film fatigue degradation after rewriting of about 10 {sup 12} times. In scaling a ferroelectric memory, if voltage is decreased in proportion with the size, the operation can be reduced proportionately according to the voltage reduction. This paper introduces a method to constitute a ferroelectric memory. 22 refs., 11 figs., 2 tabs.

  11. Comparison of lead zirconate titanate thin films on ruthenium oxide and platinum electrodes

    International Nuclear Information System (INIS)

    Bursill, L.A.; Reaney, I.M.

    1994-01-01

    High-resolution and bright- and dark-field transmission electron microscopy are used to characterize and compare the interface structures and microstructure of PZT/RuO 2 /SiO 2 /Si and PZT/Pt/Ti/SiO 2 /Si ferroelectric thin films, with a view to understanding the improved fatigue characteristics of PZT thin films with RuO 2 electrodes. The RuO 2 /PZT interface consists of a curved pseudoperiodic minimal surface. The interface is chemically sharp with virtually no intermixing of RuO 2 and PZT, as evidenced by the atomic resolution images as well as energy dispersive X-ray analysis. A nanocrystalline pyrochlore phase Pb 2 ZrTiO 7-x (x ≠ 1) was found on the top surface of the PZT layer. The PZT/Pt/Ti/SiO 2 /Si thin film was well-crystallized and showed sharp interfaces throughout. Possible reasons for the improved fatigue characteristics of PZT/RuO 2 /SiO 2 /Si thin films are discussed. 13 refs; 7 figs

  12. Comparison of lead zirconate titanate thin films on ruthenium oxide and platinum electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L A; Reaney, I M

    1994-12-31

    High-resolution and bright- and dark-field transmission electron microscopy are used to characterize and compare the interface structures and microstructure of PZT/RuO{sub 2}/SiO{sub 2}/Si and PZT/Pt/Ti/SiO{sub 2}/Si ferroelectric thin films, with a view to understanding the improved fatigue characteristics of PZT thin films with RuO{sub 2} electrodes. The RuO{sub 2}/PZT interface consists of a curved pseudoperiodic minimal surface. The interface is chemically sharp with virtually no intermixing of RuO{sub 2} and PZT, as evidenced by the atomic resolution images as well as energy dispersive X-ray analysis. A nanocrystalline pyrochlore phase Pb{sub 2}ZrTiO{sub 7-x} (x {ne} 1) was found on the top surface of the PZT layer. The PZT/Pt/Ti/SiO{sub 2}/Si thin film was well-crystallized and showed sharp interfaces throughout. Possible reasons for the improved fatigue characteristics of PZT/RuO{sub 2}/SiO{sub 2}/Si thin films are discussed. 13 refs; 7 figs.

  13. Comparison of chemical solution deposition systems for the fabrication of lead zirconate titanate thin films

    International Nuclear Information System (INIS)

    Lecarpentier, F.; Daglish, M.; Kemmitt, T.

    2001-01-01

    Ferroelectric thin films of lead zirconate titanate Pb(Zr x Ti 1-x )O 3 (PZT) were prepared from five chemical solution deposition (CSD) systems, namely methoxyethanol, citrate, diol, acetic acid and triethanolamine. Physical characteristics of the solutions, processing parameters and physical and electrical properties of the films were used to assess the relative advantages and disadvantages of the different chemical systems. All the CSD systems decomposed to produce single phase perovskite PZT at temperatures above 650 deg C. Thin film deposition was influenced by the specific characteristics of each system such as wetting on the substrate and viscosity. Distinct precursor effects on the thin film crystallinity and electrical performance were revealed. The diol route yielded films with the highest crystallite size, highest permittivity and lowest loss tangent. The relative permittivity exhibited by films made by the other routes were 25% to 35% lower at equivalent thicknesses. Copyright (2001) The Australian Ceramic Society

  14. Transparent Ferroelectric Capacitors on Glass

    Directory of Open Access Journals (Sweden)

    Daniele Sette

    2017-10-01

    Full Text Available We deposited transparent ferroelectric lead zirconate titanate thin films on fused silica and contacted them via Al-doped zinc oxide (AZO transparent electrodes with an interdigitated electrode (IDE design. These layers, together with a TiO2 buffer layer on the fused silica substrate, are highly transparent (>60% in the visible optical range. Fully crystallized Pb(Zr0.52Ti0.48O3 (PZT films are dielectrically functional and exhibit a typical ferroelectric polarization loop with a remanent polarization of 15 μC/cm2. The permittivity value of 650, obtained with IDE AZO electrodes is equivalent to the one measured with Pt electrodes patterned with the same design, which proves the high quality of the developed transparent structures.

  15. Catalytic behaviors of ruthenium dioxide films deposited on ferroelectrics substrates, by spin coating process

    International Nuclear Information System (INIS)

    Khachane, M.; Nowakowski, P.; Villain, S.; Gavarri, J.R.; Muller, Ch.; Elaatmani, M.; Outzourhite, A.; Luk'yanchuk, I.; Zegzouti, A.; Daoud, M.

    2007-01-01

    Catalytic ruthenium dioxide films were deposited by spin-coating process on ferroelectric films mainly constituted of SrBi 2 Ta 2 O 9 (SBT) and Ba 2 NaNb 5 O 15 (BNN) phases. After thermal treatment under air, these ferroelectric-catalytic systems were characterized by X-ray diffraction and scanning electron microscopy (SEM). SEM images showed that RuO 2 film morphology depended on substrate nature. A study of CH 4 conversion into CO 2 and H 2 O was carried out using these catalytic-ferroelectric multilayers: the conversion was analyzed from Fourier transform infrared (FTIR) spectroscopy, at various temperatures. Improved catalytic properties were observed for RuO 2 films deposited on BNN oxide layer

  16. Wafer-scale growth of highly textured piezoelectric thin films by pulsed laser deposition for micro-scale sensors and actuators

    Science.gov (United States)

    Nguyen, M. D.; Tiggelaar, R.; Aukes, T.; Rijnders, G.; Roelof, G.

    2017-11-01

    Piezoelectric lead-zirconate-titanate (PZT) thin films were deposited on 4-inch (111)Pt/Ti/SiO2/Si(001) wafers using large-area pulsed laser deposition (PLD). This study was focused on the homogeneity in film thickness, microstructure, ferroelectric and piezoelectric properties of PZT thin films. The results indicated that the highly textured (001)-oriented PZT thin films with wafer-scale thickness homogeneity (990 nm ± 0.8%) were obtained. The films were fabricated into piezoelectric cantilevers through a MEMS microfabrication process. The measured longitudinal piezoelectric coefficient (d 33f = 210 pm/V ± 1.6%) and piezoelectric transverse coefficient (e 31f = -18.8 C/m2 ± 2.8%) were high and homogeneity across wafers. The high piezoelectric properties on Si wafers will extend industrial application of PZT thin films and further development of piezoMEMS.

  17. Photoelectron spectroscopic and microspectroscopic probes of ferroelectrics

    Science.gov (United States)

    Tǎnase, Liviu C.; Abramiuc, Laura E.; Teodorescu, Cristian M.

    2017-12-01

    This contribution is a review of recent aspects connected with photoelectron spectroscopy of free ferroelectric surfaces, metals interfaced with these surfaces, graphene-like layers together with some exemplifications concerning molecular adsorption, dissociations and desorptions occurring from ferroelectrics. Standard photoelectron spectroscopy is used nowadays in correlation with other characterization techniques, such as piezoresponse force microscopy, high resolution transmission electron spectroscopy, and ferroelectric hysteresis cycles. In this work we will concentrate mainly on photoelectron spectroscopy and spectro-microscopy characterization of ferroelectric thin films, starting from atomically clean ferroelectric surfaces of lead zirco-titanate, then going towards heterostructures using this material in combination with graphene-like carbon layers or with metals. Concepts involving charge accumulation and depolarization near surface will be revisited by taking into account the newest findings in this area.

  18. Interface strain coupling and its impact on the transport and magnetic properties of LaMnO3 thin films grown on ferroelectrically active substrates

    International Nuclear Information System (INIS)

    Zheng, R.K.; Wang, Y.; Habermeier, H.-U.; Chan, H.L.W.; Li, X.M.; Luo, H.S.

    2012-01-01

    Highlights: ► Strong interface strain coupling in LaMnO 3 /PMN-PT heterostructure. ► In situ dynamic turning of the strain and lattice distortion of LaMnO 3 films. ► Coupling of electrons to lattice strain is crucial to understand the strain effect. - Abstract: Thin films of LaMnO 3 have been epitaxially grown on 〈0 0 1〉 oriented ferroelectric 0.67Pb(Mg 1/3 Nb 2/3 )O 3 -0.33PbTiO 3 (PMN-PT) single-crystal substrates. The poling of the PMN-PT crystal causes a decrease in the resistance and an increase in the magnetization and magnetoresistance of the LaMnO 3 film. In situ X-ray diffraction measurements revealed that these changes arise from the poling-induced strain in the PMN-PT substrate, which reduces the in-plane tensile strain and the Jahn–Teller (JT) distortion of MnO 6 octahedra of the LaMnO 3 film. Moreover, it was found that the transport properties of LaMnO 3 films are much more sensitive to the poling-induced strain than that of CaMnO 3 films for which there is no JT distortion, implying that the electron–lattice coupling is one of the most important ingredients in understanding the strain effect in LaMnO 3 films.

  19. Crystallization of sol-gel derived lead zirconate titanate thin films in argon and oxygen atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L A [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Brooks, K G [Ecole Polytechnique Federale, Lausanne (Switzerland)

    1994-12-31

    Electron diffraction and high-resolution electron microscopic techniques are applied to reveal the mechanisms of crystallization of 75 nm thin films of ferroelectric lead-zirconate-titanate (PZT). Sol-gel methods, followed by pyrolysis at 350 deg C, were used to provide a common starting point after which a variety of rapid-thermal annealing (RTA) experiments in the temperature range 400-700 deg C were made in argon, oxygen and nitrogen/hydrogen atmospheres. The results are interpreted in terms of the crystal chemical analysis, which points out that partial pressure of oxygen and heating rate are important experimental parameters which must be controlled if ferroelectric perovskite-type Pb{sub 2}ZrTiO{sub 6}, rather than pyrochlore-type Pb{sub 2}ZrTiO{sub 6+x}, where O < X < 1 or -1 < X < O, is to be obtained after the RTA step. Thus significant improvements in the crystallization of perovskite-type PZT were clearly demonstrated by using argon atmospheres for the RTA step. The results have significance for the production of high-quality ferroelectric thin films, with improved switching and fatigue characteristics, since even small amounts of the pyrochlore phase prove detrimental for these properties. 18 refs., 1 tab., 10 figs.

  20. Characterization of Pb(Zr, Ti)O3 thin films fabricated by plasma enhanced chemical vapor deposition on Ir-based electrodes

    International Nuclear Information System (INIS)

    Lee, Hee-Chul; Lee, Won-Jong

    2002-01-01

    Structural and electrical characteristics of Pb(Zr, Ti)O 3 (PZT) ferroelectric thin films deposited on various Ir-based electrodes (Ir, IrO 2 , and Pt/IrO 2 ) using electron cyclotron resonance plasma enhanced chemical vapor deposition were investigated. On the Ir electrode, stoichiometric PZT films with pure perovskite phase could be obtained over a very wide range of processing conditions. However, PZT films prepared on the IrO 2 electrode contain a large amount of PbO x phases and exhibited high Pb-excess composition. The deposition characteristics were dependent on the behavior of PbO molecules on the electrode surface. The PZT thin film capacitors prepared on the Ir bottom electrode showed different electrical properties depending on top electrode materials. The PZT capacitors with Ir, IrO 2 , and Pt top electrodes showed good leakage current characteristics, whereas those with the Ru top electrode showed a very high leakage current density. The PZT capacitor exhibited the best fatigue endurance with an IrO 2 top electrode. An Ir top electrode provided better fatigue endurance than a Pt top electrode. The PZT capacitor with an Ir-based electrode is thought to be attractive for the application to ferroelectric random access memory devices because of its wide processing window for a high-quality ferroelectric film and good polarization, fatigue, and leakage current characteristics

  1. Local Fatigue Evaluation in PZT Thin Films with Nanoparticles by Piezoresponse Force Microscopy

    OpenAIRE

    B. S. Li

    2012-01-01

    Lead zirconate titanate (PZT) thin films with the morphotropic phase boundary composition (Zr/Ti = 52/48) have been prepared using a modified diol-based sol-gel route by introducing 1–5 mol% barium titanate (BT) nanoseeds into the precursor solution on platinized silicon substrates (Pt/Ti/SiO2/Si). Macroscopic electric properties of PZT film with nanoparticle showed a significant improvement of ferroelectric properties. This work aims at the systematic study of the local switching polarizatio...

  2. Negative capacitance in a ferroelectric capacitor.

    Science.gov (United States)

    Khan, Asif Islam; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur Rahman; Ramesh, Ramamoorthy; Salahuddin, Sayeef

    2015-02-01

    The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time--in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications.

  3. Large area deposition of Pb(Zr,Ti)O.sub.3./sub. thin films for piezoelectric MEMS

    Czech Academy of Sciences Publication Activity Database

    Suchaneck, G.; Vidyarthi, V.S.; Reibold, M.; Deyneka, Alexander; Jastrabík, Lubomír; Gerlach, G.; Hartung, J.

    2008-01-01

    Roč. 20, - (2008), s. 17-20 ISSN 1385-3449 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z10100521 Keywords : ferroelectric thin films * PZT * high resolution transmission electron microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.990, year: 2008

  4. High T(sub c) superconductor/ferroelectric heterostructures

    Science.gov (United States)

    Ryder, Daniel F., Jr.

    1994-12-01

    Thin films of the ferroelectric perovskite, Ba(x) Sr(1-x) TiO3 (BST), were deposited on superconducting (100)YBa2Cu3O(x)(YBCO)/ (100)Yttria-stabilized zirconia(YSZ) substrates and (100)Si by ion-beam sputtering. Microstructural and compositional features of the ceramic bilayer were assessed by a combination of x-ray diffraction (XRD) and scanning electron microscopy. The films were smooth and featureless, and energy dispersive x-ray spectroscopy (EDX) data indicated that film composition closely matched target composition. XRD analysis showed that films deposited on YBCO substrates were highly c-axis textured, while the films deposited on (100)Si did not exhibit any preferred growth morphology. The superconducting properties of the YBCO substrate layer were maintained throughout the processing stages and, as such, it was demonstrated that ion beam sputtering is a viable method for the deposition of Ferroelectric/YBCO heterostructures.

  5. Structure-property relations in sputter deposited epitaxial (1-x)Pb(Mg1/3Nb2/3)O3- xPbTiO3 thin films

    Science.gov (United States)

    Frederick, Joshua C.

    Lead-based ferroelectric materials are of significant technological importance for sensing and actuation due to their high piezoelectric performance (i.e., the ability to convert an electrical signal to mechanical displacement, and vice versa). Traditionally, bulk ceramic or single crystals materials have filled these roles; however, emerging technologies stand to benefit by incorporating thin films to achieve miniaturization while maintaining high efficiency and sensitivity. Currently, chemical systems that have been well characterized in bulk form (e.g. Pb(Mg1/3Nb2/3)O3- xPbTiO3, or PMN-xPT) require further study to optimize both the chemistry and structure for deployment in thin film devices. Furthermore, the effect of internal electric fields is more significant at the length scales of thin films, resulting in self biases that require compensation to reveal their intrinsic dielectric response. To this end, the structure-property relations of epitaxial PMN-xPT films sputter deposited on a variety of substrates were investigated. Attention was paid to how the structure (i.e., strain state, crystal structure, domain configuration, and defects) gave rise to the ferroelectric, dielectric, and piezoelectric response. Three-dimensional visualization of the dielectric response as a simultaneous function of electric field and temperature revealed the true phase transition of the films, which was found to correspond to the strain state and defect concentration. A lead-buffered anneal process was implemented to enhance the ferroelectric and dielectric response of the films without altering their stoichiometry. It was discovered that PMN- xPT films could be domain-engineered to exhibit a mixed domain state through chemistry and substrate choice. Such films exhibited a monoclinic distortion similar to that of the bulk compositions near the morphotropic phase boundary. Finally, it was revealed that the piezoelectric response could be greatly enhanced by declamping the film

  6. Strain Engineering of Ferroelectric Domains in KxNa1−xNbO3 Epitaxial Layers

    Directory of Open Access Journals (Sweden)

    Jutta Schwarzkopf

    2017-08-01

    Full Text Available The application of lattice strain through epitaxial growth of oxide films on lattice mismatched perovskite-like substrates strongly influences the structural properties of ferroelectric domains and their corresponding piezoelectric behavior. The formation of different ferroelectric phases can be understood by a strain-phase diagram, which is calculated within the framework of the Landau–Ginzburg–Devonshire theory. In this paper, we illustrate the opportunity of ferroelectric domain engineering in the KxNa1−xNbO3 lead-free material system. In particular, the following examples are discussed in detail: (i Different substrates (NdGaO3, SrTiO3, DyScO3, TbScO3, and GdScO3 are used to systematically tune the incorporated epitaxial strain from compressive to tensile. This can be exploited to adjust the NaNbO3 thin film surface orientation and, concomitantly, the vector of electrical polarization, which rotates from mainly vertical to exclusive in-plane orientation. (ii In ferroelectric NaNbO3, thin films grown on rare-earth scandate substrates, highly regular stripe domain patterns are observed. By using different film thicknesses, these can be tailored with regard to domain periodicity and vertical polarization component. (iii A featured potassium concentration of x = 0.9 of KxNa1−xNbO3 thin films grown on (110 NdScO3 substrates favors the coexistence of two equivalent, monoclinic, but differently oriented ferroelectric phases. A complicated herringbone domain pattern is experimentally observed which consists of alternating MC and a1a2 domains. The coexistence of different types of ferroelectric domains leads to polarization discontinuities at the domain walls, potentially enabling high piezoelectric responses. In each of these examples, the experimental results are in excellent agreement with predictions based on the linear elasticity theory.

  7. Orthorhombic polar Nd-doped BiFeO3 thin film on MgO substrate

    International Nuclear Information System (INIS)

    Leontyev, I N; Janolin, P-E; Dkhil, B; Yuzyuk, Yu I; El-Marssi, M; Chernyshov, D; Dmitriev, V; Golovko, Yu I; Mukhortov, V M

    2011-01-01

    A Nd-doped BiFeO 3 thin film deposited on MgO substrate was studied by synchrotron diffraction. The ferroelectric nature of the film is proven by in-plane remanent polarization measurement. The highest possible symmetry of the film is determined to be orthorhombic, within the Fm2m space group. Such a structure is rotated by 45 0 with respect to the substrate and is consistent with tilts of oxygen octahedra doubling the unit cell. This polar structure presents a rather unusual strain-accommodation mechanism. (fast track communication)

  8. Polarization fatigue resistance of Ca-doped Pb(Zr0.52Ti0.48)O3 thin films prepared by the sol-gel method

    International Nuclear Information System (INIS)

    Wei, T.; Wang, Y.; Zhu, C.; Dong, X.W.; Xia, Y.D.; Zhu, J.S.; Liu, J.-M.

    2008-01-01

    The ferroelectric and polarization fatigue characteristics of Pb 1-x Ca x (Zr 0.52 Ti 0.48 )O 3 (PCZT) thin films prepared using the sol-gel method were studied. The Ca-doping slightly suppresses the ferroelectricity of Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) because of the quantum paraelectric behavior of CaTiO 3 . Compared with PZT thin films, the PCZT (x=0.2) thin films show enhanced fatigue resistance at room temperature, further emphasized by the almost fatigue-free behavior at 100 K. The temperature-dependent dc-conductivity suggests a decrease of the oxygen vacancy density by almost 20 times and a slightly declined activation energy U for oxygen vacancies, upon increasing of the Ca-doping content from 0.0 to 0.2. It is argued that the improved fatigue endurance is ascribed to the decreasing density of oxygen vacancies due to the Ca-doping, although the lowered activation energy of oxygen vacancies is unfavorable. (orig.)

  9. Effect of substrate temperature in the structural, optical and ferroelectric properties of thin films of BaTiO{sub 3} deposited by RF sputtering; Efecto de la temperatura de substrato en las propiedades estructurales, opticas y ferroelectricas de peliculas delgadas de BaTiO{sub 3} depositadas por RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Marquez H, A. [Universidad Autonoma de San Luis Potosi, Coordinacion Academica Region Altiplano, Carretera a Cedral Km. 5 -600, Matehuala, 78800 San Luis Potosi (Mexico); Hernandez R, E.; Zapata T, M. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria, Calz. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Calzadilla A, O. [Universidad de la Habana, Facultad de Fisica-IMRE, San Lazaro y L. Municipio Plaza de la Revolucion, La Habana (Cuba); Melendez L, M. [IPN, Centro de Investigacion y de Estudios Avanzados, Departamento de Fisica, Apdo. Postal 14-740, 07000 Mexico D. F. (Mexico)

    2012-07-01

    Thin films of Barium Titanate (BaTiO{sub 3}) were grown on nichrome and quartz substrates, using a BaTiO{sub 3} target, by RF sputtering technique. We varied the substrate temperature in order to study its effect on the structural, optical and ferroelectric properties of the samples. The results of the X-ray diffraction showed tetragonal structure with increases of the crystallinity as increases the substrate temperature. Furthermore, it observed by ultraviolet-visible spectroscopy that the band gap decreased as the substrate temperature increases showing abrupt sharp decrease at 494.8{sup o} C. The ferroelectric properties of the films showed a dependence with substrate temperature, the best ferroelectric answer was obtained at 494.8{sup o} C. (Author)

  10. Determination of the Steady State Leakage Current in Structures with Ferroelectric Ceramic Films

    Science.gov (United States)

    Podgornyi, Yu. V.; Vorotilov, K. A.; Sigov, A. S.

    2018-03-01

    Steady state leakage currents have been investigated in capacitor structures with ferroelectric solgel films of lead zirconate titanate (PZT) formed on silicon substrates with a lower Pt electrode. It is established that Pt/PZT/Hg structures, regardless of the PZT film thickness, are characterized by the presence of a rectifying contact similar to p-n junction. The steady state leakage current in the forward direction increases with a decrease in the film thickness and is determined by the ferroelectric bulk conductivity.

  11. The effect of Nb doping on ferroelectric properties of PZT thin films prepared from polymeric precursors

    International Nuclear Information System (INIS)

    Souza, E.C.F.; Simoes, A.Z.; Cilense, M.; Longo, E.; Varela, J.A.

    2004-01-01

    Pure and Nb doped PbZr 0.4 Ti 0.6 O 3 thin films was prepared by the polymeric precursor method and deposited by spin coating on Pt/Ti/SiO 2 /Si (100) substrates and annealed at 700 deg. C. The films are oriented in (1 1 0) and (1 0 0) direction. The electric properties of PZT thin films show strong dependence of the crystallographic orientation. The P-E hysteresis loops for the thin film with composition PbZr 0.39 Ti 0.6 Nb 0.1 O 3 showed good saturation, with values for coercive field (E c ) equal to 60 KV cm -1 and for remanent polarization (P r ) equal to 20 μC cm -2 . The measured dielectric constant (ε) is 1084 for this film. These results show good potential for application in FERAM

  12. Effects of ferroelectric-poling-induced strain on the electronic transport and magnetic properties of (001)- and (111)-oriented La{sub 0.5}Ba{sub 0.5}MnO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.Y. [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zheng, M.; Zhu, Q.X.; Yang, M.M.; Li, X.M.; Shi, X. [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Yuan, G.L., E-mail: yuanguoliang@mail.njust.edu.cn [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Y.; Chan, H.L.W. [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China); Li, X.G. [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei 230026 (China); Luo, H.S. [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zheng, R.K., E-mail: zrk@ustc.edu [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2014-04-01

    We epitaxially grew La{sub 0.5}Ba{sub 0.5}MnO{sub 3} (LBMO) films on (001)- and (111)-oriented ferroelectric single-crystal substrates and reduced the in-plane tensile strain of LBMO films by poling the ferroelectric substrates along the 〈001〉 or 〈111〉 direction. Upon poling, a large decrease in the resistance and a considerable increase in the magnetization, Curie temperature, and magnetoresistance were observed for the LBMO film, which are driven by interface strain coupling. Such strain effects can be significantly enhanced by the application of a magnetic field. An overall analysis of the findings reveals that the mutual interaction between the strain and the magnetic field is mediated by the electronic phase separation which is sensitive to both strain and magnetic field. Our findings highlight that the electronic phase separation is crucial in understanding the electric-field-manipulated strain effects in manganite film/ferroelectric crystal heterostructures. - Highlights: • La{sub 0.5}Ba{sub 0.5}MnO{sub 3} films were epitaxially grown on ternary ferroelectric single crystals. • Ferroelectric poling modifies the strain and physical properties of films. • Magnetic field enhances the strain effects of films. • Phase separation is crucial to understand the magnetic-field-tuned strain effect.

  13. Reduction of etching damage in lead-zirconate-titanate thin films with inductively coupled plasma

    International Nuclear Information System (INIS)

    Lim, Kyu-Tae; Kim, Kyoung-Tae; Kim, Dong-Pyo; Kim, Chang-Il

    2003-01-01

    In this work, we etched lead-zirconate-titanate (PZT) films with various additive gases (O 2 and Ar) in Cl 2 /CF 4 plasmas, while mixing ratio was fixed at 8/2. After the etching, the plasma induced damages are characterized in terms of hysteresis curves, leakage current, retention properties, and switching polarization. When the electrical properties of PZT etched in O 2 or Ar added to Cl 2 /CF 4 were compared, the value of remanent polarization in O 2 added to Cl 2 /CF 4 plasma is higher than that in Ar added plasma. The maximum etch rate of the PZT thin films was 145 nm/min for 30% Ar added Cl 2 /CF 4 gas having mixing ratio of 8/2 and 110 nm/min for 10% O 2 added to that same gas mixture. In order to recover the ferroelectric properties of the PZT thin films after etching, we annealed the etched PZT thin films at 550 deg. C in an O 2 atmosphere for 10 min. From the hysteresis curves, leakage current, retention property, and switching polarization, the reduction of the etching damage and the recovery via the annealing turned out to be more effective when O 2 was added to Cl 2 /CF 4 than Ar. X-ray diffraction showed that the structural damage was lower when O 2 was added to Cl 2 /CF 4 and the improvement in the ferroelectric properties of the annealed samples was consistent with the increased intensities of the (100) and the (200) PZT peaks

  14. Characterization of PZT thin films on metal substrates; Charakterisierung von PZT-Duennschichten auf Metallsubstraten

    Energy Technology Data Exchange (ETDEWEB)

    Dutschke, A.

    2008-02-02

    Lead zirconate titanate (PbZr{sub x}Ti{sub 1-x}O{sub 3},PZT) is one of the most applied ceramic materials because of its distinctive piezo- and ferroelectric properties. Prepared as thin films on flexible, metallic substrates it can be used for various applications as strain gauges, key switches, vibration dampers, microactuators and ultrasonic transducers. The aim of this work is to analyze the microstructure and the phase-content of PZT-thin films deposited on temperature- und acid-resistant hastelloy-sheets, to correlate the results with the ferroelectric and dielectric properties. It is demonstrated, that the specific variation of the microstructure can be achieved by different thermal treatments and the selective addition of Neodymium as dopant. Nd-doping leads to a shift of the maximum nucleation rate towards reduced temperatures and a decrease in the rate of growth compared to undoped films. The PZT-films are prepared by a sol-gel-process in fourfold multilayers with a composition near the morphotropic phase boundary, where the tetragonal und rhombohedral perovskite-phases coexist. The crystallisation in Nd-doped and undoped films takes place heterogeneously, preferentially at the interfaces and on the surface of the multilayered films as well as on the inner surface of pores within the films. For the first time, the Zr:Ti fluctuation phenomena emerging in sol-gel derived PZT films is related to the microstructure and the local phase content on a nanometer scale. In this connection it is proved, that long-distance Zr:Ti gradients arise preferentially before and during the crystallisation of the pyrochlore phase. During the following crystallisation of the perovskite phase, the crystallites grow across these gradients without modifying them. It is pointed out that the fluctuation in the Zr:Ti ratio has only minor influence on the amount of the tetragonal or rhombohedral distortion of the crystallites after the transition from the para- to the ferroelectric

  15. Thin PZT-Based Ferroelectric Capacitors on Flexible Silicon for Nonvolatile Memory Applications

    KAUST Repository

    Ghoneim, Mohamed T.; Zidan, Mohammed A.; Al-Nassar, Mohammed Y.; Hanna, Amir; Kosel, Jü rgen; Salama, Khaled N.; Hussain, Muhammad Mustafa

    2015-01-01

    A flexible version of traditional thin lead zirconium titanate ((Pb1.1Zr0.48Ti0.52O3)-(PZT)) based ferroelectric random access memory (FeRAM) on silicon shows record performance in flexible arena. The thin PZT layer requires lower operational

  16. Preparation and switching kinetics of Pb(Zr, Ti)O3 thin films deposited by reactive sputtering

    International Nuclear Information System (INIS)

    Hase, Takashi; Shiosaki, Tadashi

    1991-01-01

    Ferroelectric Pb(Zr, Ti)O 3 [PZT] thin films have been prepared on Pt/Ti/SiO 2 /Si and Pt/SiO 2 /Si substrates using the reactive sputtering method with a metal composite target. The (111)-oriented PZT (80/20) thin films with a perovskite structure have been obtained at a substrate temperature of 595degC on highly (111)-oriented Pt films formed on SiO 2 /Si substrates. When an 8 V pulse sequence was applied to a 265 nm-thick film with an electrode area of 50 x 50 μm 2 , the switching time and the switched charge density measured were 20 ns and 10 μC/cm 2 , respectively. The switching time was strongly dependent on the electrode area. (author)

  17. Control of retention and fatigue-free characteristics in CaBi4Ti4O15 thin films prepared by chemical method

    International Nuclear Information System (INIS)

    Simoes, A.Z.; Ramirez, M.A.; Gonzalez, A.H.M.; Riccardi, C.S.; Ries, A.; Longo, E.; Varela, J.A.

    2006-01-01

    Ferroelectric CaBi 4 Ti 4 O 15 (CBTi144) thin films were deposited on Pt/Ti/SiO 2 /Si substrates by the polymeric precursor method. The films present a single phase of layered-structured perovskite with polar axis orientation after annealing at 700 deg. C for 2 h in static air and oxygen atmosphere. The a/b-axis orientation of the ferroelectric film is considered to be associated with the preferred orientation of the Pt bottom electrode. It is noted that the films annealed in static air showed good polarization fatigue characteristics at least up to 10 10 bipolar pulse cycles and excellent retention properties up to 10 4 s. On the other hand, oxygen atmosphere seems to be crucial in the decrease of both, fatigue and retention characteristics of the capacitors. Independently of the applied electric field, the retained switchable polarization approached a nearly steady-state value after a retention time of 10 s. - Graphical abstract: Fatigue of CBTi144 thin film obtained by polymeric precursor method

  18. A flexible tactile-feedback touch screen using transparent ferroelectric polymer film vibrators

    International Nuclear Information System (INIS)

    Ju, Woo-Eon; Moon, Yong-Ju; Park, Cheon-Ho; Choi, Seung Tae

    2014-01-01

    To provide tactile feedback on flexible touch screens, transparent relaxor ferroelectric polymer film vibrators were designed and fabricated in this study. The film vibrator can be integrated underneath a transparent cover film or glass, and can also produce acoustic waves that cause a tactile sensation on human fingertips. Poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] polymer was used as the relaxor ferroelectric polymer because it produces a large strain under applied electric fields, shows a fast response, and has excellent optical transparency. The natural frequency of this tactile-feedback touch screen was designed to be around 200–240 Hz, at which the haptic perception of human fingertips is the most sensitive; therefore, the resonance of the touch screen at its natural frequency provides maximum haptic sensation. A multilayered relaxor ferroelectric polymer film vibrator was also demonstrated to provide the same vibration power at reduced voltage. The flexible P(VDF-TrFE-CTFE) film vibrators developed in this study are expected to provide tactile sensation not only in large-area flat panel displays, but also in flexible displays and touch screens. (papers)

  19. A two-step annealing process for enhancing the ferroelectric properties of poly(vinylidene fluoride) (PVDF) devices

    KAUST Repository

    Park, Jihoon

    2015-01-01

    We report a simple two-step annealing scheme for the fabrication of stable non-volatile memory devices employing poly(vinylidene fluoride) (PVDF) polymer thin-films. The proposed two-step annealing scheme comprises the crystallization of the ferroelectric gamma-phase during the first step and enhancement of the PVDF film dense morphology during the second step. Moreover, when we extended the processing time of the second step, we obtained good hysteresis curves down to 1 Hz, the first such report for ferroelectric PVDF films. The PVDF films also exhibit a coercive field of 113 MV m-1 and a ferroelectric polarization of 5.4 μC cm-2. © The Royal Society of Chemistry 2015.

  20. Strain and Defect Engineering for Tailored Electrical Properties in Perovskite Oxide Thin Films and Superlattices

    Science.gov (United States)

    Hsing, Greg Hsiang-Chun

    Functional complex-oxides display a wide spectrum of physical properties, including ferromagnetism, piezoelectricity, ferroelectricity, photocatalytic and metal-insulating transition (MIT) behavior. Within this family, oxides with a perovskite structure have been widely studied, especially in the form of thin films and superlattices (heterostructures), which are strategically and industrially important because they offer a wide range of opportunities for electronic, piezoelectric and sensor applications. The first part of my thesis focuses on understanding and tuning of the built-in electric field found in PbTiO3/SrTiO3 (PTO/STO) ferroelectric superlattices and other ferroelectric films. The artificial layering in ferroelectric superlattices is a potential source of polarization asymmetry, where one polarization state is preferred over another. One manifestation of this asymmetry is a built-in electric field associated with shifted polarization hysteresis. Using off-axis RF-magnetron sputtering, we prepared several compositions of PTO/STO superlattice thin films; and for comparison PbTiO3/SrRuO 3 (PTO/SRO) superlattices, which have an additional intrinsic compositional asymmetry at the interface. Both theoretical modeling and experiments indicate that the layer-by-layer superlattice structure aligns the Pb-O vacancy defect dipoles in the c direction which contributes significantly to the built-in electric field; however the preferred polarization direction is different between the PTO/STO and PTO/SRO interface. By designing a hybrid superlattice that combines PTO/STO and PTO/SRO superlattices, we show the built-in electric field can be tuned to zero by changing the composition of the combo-superlattice. The second part of my thesis focuses on the epitaxial growth of SrCrO 3 (SCO) films. The inconsistent reports regarding its electrical and magnetic properties through the years stem from the compositionally and structurally ill-defined polycrystalline samples, but

  1. PREFACE: Proceedings Symposium G of E-MRS Spring Meeting on Fundamentals and Technology of Multifunctional Oxide Thin Films

    Science.gov (United States)

    2010-07-01

    Oxide materials exhibit a large variety of functional properties that are useful in a plethora of applications. Symposium G focused on oxide thin films that include dielectric or switching properties. Its program mirrored very well the strong worldwide search for high-K thin films for gate, memory, and on-chip capacitors, as well as the emerging field of functional thin films for MEMS. A complete session was devoted to the colossal effect of dielectric response in (Ca,Cu)TiO3, representing the major European research groups in this field. A comprehensive overview on this phenomenon was given by D Sinclair J Wolfman presented the latest results on CCTO thin films obtained by wafer scale pulsed laser deposition. A Loidl showed the analytical power of dielectric spectroscopy when covering the complete frequency range from 1-1012 Hz, i.e. from space charge to phonon contributions at the example of CCTO. Another session was devoted to applications in non-volatile memories, covering various effects including ferroelectric and resistive switching, the complex behavior of oxide tunnel junctions (H Kohlstedt), the possibility to manipulate the magnetic state of a 2d-electron gas by the polarization of an adjacent ferroelectric gate (I Stolitchnov). Latest advancements in ALD processing for high-K thin films in dynamic RAM were reported by S Ramanathan. The advancement of piezoelectric PZT thin film MEMS devices was well documented by outstanding talks on their developments in industry (M Klee, F Tyholdt), new possibilities in GHz filters (T Matshushima), advancements in sol-gel processing (B Tuttle, H Suzuki), and low temperature integration approaches by UV light curing (S Trolier-McKinstry). Recent advances in incipient ferroelectric thin films and nano composites for tunable capacitors in microwave applications were present by A Vorobiev and T Yamada. Integrated electro-optics is another field to be conquered by thin film structures. The impressive progress made in this

  2. Granular and layered ferroelectric–ferromagnetic thin-film nanocomposites as promising materials with high magnetotransmission effect

    Energy Technology Data Exchange (ETDEWEB)

    Akbashev, A.R. [Department of Materials Science, Moscow State University, 119992 Moscow (Russian Federation); Telegin, A.V., E-mail: telegin@imp.uran.ru [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620990 Ekaterinburg (Russian Federation); Kaul, A.R. [Department of Chemistry, Moscow State University, 119992 Moscow (Russian Federation); Sukhorukov, Yu.P. [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620990 Ekaterinburg (Russian Federation)

    2015-06-15

    Epitaxial thin films of granular and layered nanocomposites consisting of ferromagnetic perovskite Pr{sub 1–x}Sr{sub x}MnO{sub 3} and ferroelectric hexagonal LuMnO{sub 3} were grown on ZrO{sub 2}(Y{sub 2}O{sub 3}) substrates using metal-organic chemical vapor deposition (MOCVD). A self-organized growth of the granular composite took place in situ as a result of phase separation of the Pr–Sr–Lu–Mn–O system into the perovskite and hexagonal phases. Optical transmission measurements revealed a large negative magnetotransmission effect in the layered nanocomposite over a wide spectral and temperature range. The granular nanocomposite unexpectedly showed an even larger, but positive, magnetotransmission effect at room temperature. - Highlights: • Thin-film ferromagnetic–ferroelectric nanocomposites have been prepared by MOCVD. • Giant change of optical transparency of nanocomposites in magnetic field was detected. • Positive magnetotransmission in the granular nanocomposite was discovered in the IR. • Negative magnetotransmission in the layered nanocomposite was revealed in the IR. • Ferroelectric–ferromangetic nanocomposite is a promising material for optoelectronics.

  3. Granular and layered ferroelectric–ferromagnetic thin-film nanocomposites as promising materials with high magnetotransmission effect

    International Nuclear Information System (INIS)

    Akbashev, A.R.; Telegin, A.V.; Kaul, A.R.; Sukhorukov, Yu.P.

    2015-01-01

    Epitaxial thin films of granular and layered nanocomposites consisting of ferromagnetic perovskite Pr 1–x Sr x MnO 3 and ferroelectric hexagonal LuMnO 3 were grown on ZrO 2 (Y 2 O 3 ) substrates using metal-organic chemical vapor deposition (MOCVD). A self-organized growth of the granular composite took place in situ as a result of phase separation of the Pr–Sr–Lu–Mn–O system into the perovskite and hexagonal phases. Optical transmission measurements revealed a large negative magnetotransmission effect in the layered nanocomposite over a wide spectral and temperature range. The granular nanocomposite unexpectedly showed an even larger, but positive, magnetotransmission effect at room temperature. - Highlights: • Thin-film ferromagnetic–ferroelectric nanocomposites have been prepared by MOCVD. • Giant change of optical transparency of nanocomposites in magnetic field was detected. • Positive magnetotransmission in the granular nanocomposite was discovered in the IR. • Negative magnetotransmission in the layered nanocomposite was revealed in the IR. • Ferroelectric–ferromangetic nanocomposite is a promising material for optoelectronics

  4. Texture control and seeded nucleation of nanosize structures of ferroelectric thin films

    Science.gov (United States)

    Muralt, Paul

    2006-09-01

    An overview is given on nucleation phenomena of Pb(Zr ,Ti)O3 (PZT) thin films on Pt(111)-based substrates. Emphasis is given on in situ growth methods, particularly in situ reactive sputtering from three metallic targets. Growth of PZT thin films is discussed from the point of view of the PbOx-TiO2 phase diagram, PbO vapor pressure, and classical nucleation theory. The role of thin TiO2 affinity layers and spots is explained in the frame of this theory. Activation energies for desorption and chemisorption are adapted to comply with the fact that nucleation rates on TiO2 are much larger than the ones on bare Pt(111). The model reproduces well the PbO surface flux from bare Pt(111) to the affinity spots in the case of PbTiO3 nucleation and the reversed tendency in the case of PZT 40/60 nucleation, explaining experimental observations. The critical size of nuclei was calculated to contain 8-10unit cells for PbTiO3/Pt nucleation and 14-17 for PZT/Pt nucleation.

  5. Damage-free patterning of ferroelectric lead zirconate titanate thin films for microelectromechanical systems via contact printing

    Science.gov (United States)

    Welsh, Aaron

    This thesis describes the utilization and optimization of the soft lithographic technique, microcontact printing, to additively pattern ferroelectric lead zirconate titanate (PZT) thin films for application in microelectromechanical systems (MEMS). For this purpose, the solution wetting, pattern transfer, printing dynamics, stamp/substrate configurations, and processing damages were optimized for incorporation of PZT thin films into a bio-mass sensor application. This patterning technique transfers liquid ceramic precursors onto a device stack in a desired configuration either through pattern definition in the stamp, substrate or both surfaces. It was determined that for ideal transfer of the pattern from the stamp to the substrate surface, wetting between the solution and the printing surface is paramount. To this end, polyurethane-based stamp surfaces were shown to be wet uniformly by polar solutions. Patterned stamp surfaces revealed that printing from raised features onto flat substrates could be accomplished with a minimum feature size of 5 mum. Films patterned by printing as a function of thickness (0.1 to 1 mum) showed analogous functional properties to continuous films that were not patterned. Specifically, 1 mum thick PZT printed features had a relative permittivity of 1050 +/- 10 and a loss tangent of 2.0 +/- 0.4 % at 10 kHz; remanent polarization was 30 +/- 0.4 muC/cm 2 and the coercive field was 45 +/- 1 kV/cm; and a piezoelectric coefficient e31,f of -7 +/- 0.4 C/m2. No pinching in the minor hysteresis loops or splitting of the first order reversal curve (FORC) distributions was observed. Non-uniform distribution of the solution over the printed area becomes more problematic as feature size is decreased. This resulted in solutions printed from 5 mum wide raised features exhibiting a parabolic shape with sidewall angles of ˜ 1 degree. As an alternative, printing solutions from recesses in the stamp surface resulted in more uniform solution thickness

  6. Ferroelectric tunneling element and memory applications which utilize the tunneling element

    Science.gov (United States)

    Kalinin, Sergei V [Knoxville, TN; Christen, Hans M [Knoxville, TN; Baddorf, Arthur P [Knoxville, TN; Meunier, Vincent [Knoxville, TN; Lee, Ho Nyung [Oak Ridge, TN

    2010-07-20

    A tunneling element includes a thin film layer of ferroelectric material and a pair of dissimilar electrically-conductive layers disposed on opposite sides of the ferroelectric layer. Because of the dissimilarity in composition or construction between the electrically-conductive layers, the electron transport behavior of the electrically-conductive layers is polarization dependent when the tunneling element is below the Curie temperature of the layer of ferroelectric material. The element can be used as a basis of compact 1R type non-volatile random access memory (RAM). The advantages include extremely simple architecture, ultimate scalability and fast access times generic for all ferroelectric memories.

  7. Orthorhombic polar Nd-doped BiFeO{sub 3} thin film on MgO substrate

    Energy Technology Data Exchange (ETDEWEB)

    Leontyev, I N; Janolin, P-E; Dkhil, B [Laboratoire Structures, Proprietes et Modelisation des Solides, UMR CNRS-Ecole Centrale Paris, 92295 Chatenay-Malabry Cedex (France); Yuzyuk, Yu I [Faculty of Physics, Southern Federal University, Zorge 5, Rostov-on-Don 344090 (Russian Federation); El-Marssi, M [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Chernyshov, D; Dmitriev, V [Swiss-Norwegian Beam Lines at ESRF, Boite Postale 220, F-38043 Grenoble (France); Golovko, Yu I; Mukhortov, V M, E-mail: i.leontiev@rambler.ru [Southern Scientific Center RAS, Rostov-on-Don, 344006 (Russian Federation)

    2011-08-24

    A Nd-doped BiFeO{sub 3} thin film deposited on MgO substrate was studied by synchrotron diffraction. The ferroelectric nature of the film is proven by in-plane remanent polarization measurement. The highest possible symmetry of the film is determined to be orthorhombic, within the Fm2m space group. Such a structure is rotated by 45{sup 0} with respect to the substrate and is consistent with tilts of oxygen octahedra doubling the unit cell. This polar structure presents a rather unusual strain-accommodation mechanism. (fast track communication)

  8. Fundamental Mechanisms of Roughening and Smoothing During Thin Film Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Headrick, Randall [Univ. of Vermont, Burlington, VT (United States)

    2016-03-18

    pulsed nature of the deposition where particles arrive at the growth surface in an interval of a few microseconds. We have observed effects such as transient formation of two dimensional islands on elemental crystalline surfaces. Pulsed deposition may also lead to non-equilibrium phases in some cases, such as the observation anomalously high tetragonality for ferroelectric thin films. All of the results described above feature in-situ synchrotron X-ray scattering as the main experimental method, which has become an indispensable technique for observing the kinetics of structures forming in real-time. We have also investigated in-situ coherent X-ray scattering and have developed methods to characterize temporal correlations that are not possible to observe with low-coherence X-rays. A high profile result of this work is a new technique to monitor defect propagation velocities in thin films. This has practical significance since defects limit the properties of thin films and it is desirable to understand their properties and origin in order to control them for practical applications. More broadly, amorphous thin films and multilayers have applications in optical devices, including mirrors and filters. Epitaxial thin films and multilayers have applications in electronic devices such as ferroelectric multilayers for non-volatile data storage, and thermoelectric nanostructures for energy conversion. Our progress in this project points the way for improved deposition methods and for improved simulation and modeling of thin film deposition processes for nanoscale control of materials with novel applications in these areas.

  9. Intrinsic stability of ferroelectric and piezoelectric properties of epitaxial PbZr0.45Ti0.55O3 thin films on silicon in relation to grain tilt

    Directory of Open Access Journals (Sweden)

    Evert P Houwman, Minh D Nguyen, Matthijn Dekkers and Guus Rijnders

    2013-01-01

    Full Text Available Piezoelectric thin films of PbZr0.45Ti0.55O3 were grown on Si substrates in four different ways, resulting in different crystalline structures, as determined by x-ray analysis. The crystalline structures were different in the spread in tilt angle and the in-plane alignment of the crystal planes between different grains. It is found that the deviations of the ferroelectric polarization loop from that of the ideal rectangular loop (reduction of the remanent polarization with respect to the saturation polarization, dielectric constant of the film, slanting of the loop, coercive field value all scale with the average tilt angle. A model is derived based on the assumption that the tilted grain boundaries between grains affect the film properties locally. This model describes the observed trends. The effective piezoelectric coefficient d33,eff shows also a weak dependence on the average tilt angle for films grown in a single layer, whereas it is strongly reduced for the films deposited in multiple layers. The least affected properties are obtained for the most epitaxial films, i.e. grown on a SrTiO3 epitaxial seed layer, by pulsed laser deposition. These films are intrinsically stable and do not require poling to acquire these stable properties.

  10. Investigation of the epitaxial growth of Pb(Zr{sub 0,52}Ti{sub 0,48})O{sub 3} thin films and their application in ferroelectric superconducting field effect transistors; Untersuchung des epitaktischen Wachstums duenner Pb(Zr{sub 0,52}Ti{sub 0,48})O{sub 3}-Schichten und ihre Anwendung in ferroelektrischen supraleitenden Feldeffektransistoren

    Energy Technology Data Exchange (ETDEWEB)

    Aidam, R

    1999-02-01

    The influences of the polarization of ferroelectric Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) films on the properties of YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) films were investigated in ferroelectric superconducting field effect transistors (FSuFETs). First the epitaxial growth of PZT films deposited by reactive sputtering in an argon/oxygen atmosphere was investigated. SrTiO{sub 3} single crystals and YBCO thin films proved as suitable substrates. The lead content of the PZT films depended sensitively on the deposition temperature T{sub s} and the gas pressure. By using a high pressure of 0.26 mbar the correct stoichiometry could be achieved up to an maximum T{sub s} of 580 C. Above a minimum T{sub s} of 540 C the ferroelectric perovskite structure grew. In the optimum temperature range between 560 C and 580 C the films grew with a minimum mosaic spread of {delta}{omega} < 0.3 and a small amount of less than 1% of paraelectric phase. The best ferroelectric properties could be obtained for films with the highest degree of epitaxy and the correct stoichiometry. The maximum remanent polarization amounted P{sub r} = 61 {mu}C/cm{sup 2} and the coercive field E{sub C} was 150 kV/cm at 77 K. The breakdown field was four to five times larger than E{sub C}. Fatigue studies revealed a loss of switchable polarization of 30% after 10{sup 8} cycles at 77 K, whereas loss of retention and the effect of ageing were negligible. During the process of oxidation of the heterostructure at 400 C and an oxygen pressure of 800 mbar a reaction at the PZT/YBCO interface was observed, which lead to a degradation of the transport properties of the superconductor. This reaction could be avoided by a thin SrTiO{sub 3} buffer layer without disturbing the ferroelectric hysteresis essentially.

  11. Crystallization behavior and domain structure in textured Pb(Zr0.52Ti0.48)O3 thin films by different annealing processes

    International Nuclear Information System (INIS)

    Huang, W.; Jiang, S.W.; Li, Y.R.; Zhu, J.; Zhang, Y.; Wei, X.H.; Zeng, H.Z.

    2006-01-01

    Amorphous Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films were prepared on the Pt/Ti/SiO 2 /Si substrates by radio-frequency magnetron sputtering at room temperature. After rapid thermal annealing (RTA) and conventional furnace annealing (CFA) at different temperatures, the films were transformed into polycrystalline PZT thin films with (111) and (100) orientation, respectively. The phase formation and ferroelectric domains correlated with different orientation were systematically investigated by X-ray diffraction and piezoresponse force microscopy. The results showed that the perovskite PZT crystal with [111] orientation hetero-nucleated preferentially on top of the PtPb intermetallic phase at the PZT/Pt interface during RTA process. It is of interest to find that the domain self-organized into a structure with rounded shape at the early stage of crystallization. While the nucleation of the films treated by CFA dominantly homo-nucleated, thus the (100) orientation grains with minimum surface energy were easy to grow. The texture effects on ferroelectric properties of PZT films were also discussed in relation to the domain structure

  12. Nonlinear dielectric thin films for high-power electric storage with energy density comparable with electrochemical supercapacitors.

    Science.gov (United States)

    Yao, Kui; Chen, Shuting; Rahimabady, Mojtaba; Mirshekarloo, Meysam Sharifzadeh; Yu, Shuhui; Tay, Francis Eng Hock; Sritharan, Thirumany; Lu, Li

    2011-09-01

    Although batteries possess high energy storage density, their output power is limited by the slow movement of charge carriers, and thus capacitors are often required to deliver high power output. Dielectric capacitors have high power density with fast discharge rate, but their energy density is typically much lower than electrochemical supercapacitors. Increasing the energy density of dielectric materials is highly desired to extend their applications in many emerging power system applications. In this paper, we review the mechanisms and major characteristics of electric energy storage with electrochemical supercapacitors and dielectric capacitors. Three types of in-house-produced ferroic nonlinear dielectric thin film materials with high energy density are described, including (Pb(0.97)La(0.02))(Zr(0.90)Sn(0.05)Ti(0.05))O(3) (PLZST) antiferroelectric ceramic thin films, Pb(Zn(1/3)Nb(2/3))O(3-)Pb(Mg(1/3)Nb(2/3))O(3-)PbTiO(3) (PZN-PMN-PT) relaxor ferroelectric ceramic thin films, and poly(vinylidene fluoride) (PVDF)-based polymer blend thin films. The results showed that these thin film materials are promising for electric storage with outstandingly high power density and fairly high energy density, comparable with electrochemical supercapacitors.

  13. Ferroelectric properties of tungsten bronze morphotropic phase boundary systems

    International Nuclear Information System (INIS)

    Oliver, J.R.; Neurgaonkar, R.R.; Cross, L.E.; Pennsylvania State Univ., University Park, PA

    1989-01-01

    Tungsten bronze ferroelectrics which have a morphotropic phase boundary (MPB) can have a number or enhanced dielectric, piezoelectric, and electrooptic properties compared to more conventional ferroelectric materials. The structural and ferroelectric properties of several MPB bronze systems are presented, including data from sintered and hot-pressed ceramics, epitaxial thin films, and bulk single crystals. Included among these are three systems which had not been previously identified as morphotropic. The potential advantages and limitations of these MPB systems are discussed, along with considerations of the appropriate growth methods for their possible utilization in optical, piezoelectric, or pyroelectric device applications

  14. Resistive switching in polycrystalline YMnO3 thin films

    Directory of Open Access Journals (Sweden)

    A. Bogusz

    2014-10-01

    Full Text Available We report a unipolar, nonvolatile resistive switching in polycrystalline YMnO3 thin films grown by pulsed laser deposition and sandwiched between Au top and Ti/Pt bottom electrodes. The ratio of the resistance in the OFF and ON state is larger than 103. The observed phenomena can be attributed to the formation and rupture of conductive filaments within the multiferroic YMnO3 film. The generation of conductive paths under applied electric field is discussed in terms of the presence of grain boundaries and charged domain walls inherently formed in hexagonal YMnO3. Our findings suggest that engineering of the ferroelectric domains might be a promising route for designing and fabrication of novel resistive switching devices.

  15. Analysis of multiferroic properties in BiMnO3 thin films

    International Nuclear Information System (INIS)

    Grizalez, M; Mendoza, G A; Prieto, P

    2009-01-01

    Textured BiMnO 3 [111] thin films on SrTiO 3 (100) and Pt/TiO 2 /SiO 2 substrates were grown via r.f. magnetron sputtering (13.56 MHz). The XRD spectra confirmed a monoclinic structure and high-quality textured films for the BiMnO 3 films. The films grown on SrTiO 3 (100) showed higher crystalline quality than those developed on Pt/TiO 2 /SiO 2 . Through optimized oxygen pressure of 5x10 -2 mbar during the r.f. sputtering deposition, the crystalline orientation of the BiMnO 3 film was improved with respect to the previously reported value of 2x10 -1 mbar. The values of spontaneous polarization (P s ), remnant polarization (P r ), and coercive field (F c ) from ferroelectric hysteresis loops (P-E) at different temperatures were also obtained. Samples with higher crystalline order revealed better dielectric properties (high P s and P r values and a low F c ). For films on both types of substrates, the ferroelectric behavior was found to persist up to 400K. Measurements at higher temperatures were difficult to obtain given the increased conductivity of the films. Magnetic hysteresis loops from 5K to 120K were obtained for BiMnO 3 films grown on SrTiO 3 and Pt/TiO 2 /SiO 2 substrates. The results suggested that the coexistence of the magnetic and electric phases persists up to 120K.

  16. Effects of Nb doping on the microstructure, ferroelectric and ...

    Indian Academy of Sciences (India)

    ·cm) and the poor piezoelectric performance and weak ferroelectricity are observed after the addition of .... 9.81–13.88% (<15%) and the goodness-of-fit indicator S ..... the Open Project of State Key Laboratory of Electronic Thin. Films and ...

  17. Size effects on structural and dielectric properties of PZT thin films at compositions around the morpho tropic phase boundary

    International Nuclear Information System (INIS)

    Lima, Elton Carvalho; Araujo, Eudes Borges; Souza Filho, Antonio Gomes de; Bdikin, Igor

    2011-01-01

    Full text: The demand for portability in consumer electronics has motivated the understanding of size effects on ferroelectric thin films. The actual comprehension of these effects in ferroelectrics is unsatisfactory, since the polarization interacts more strongly than other order parameters such as strain and charge. As a result, extrinsic effects are produced if these variables are uncontrolled and problems such as ferroelectric paraelectric phase transition at nanometers scale remains an unsolved issue. In the present work, the effects of thickness and compositional fractions on the structural and dielectric properties of PbZr 1-x Ti x O 3 (PZT) thin films were studied at a composition around the morphotropic phase boundary (x = 0.50). For this purpose, thin films with different thicknesses and different PbO excess were deposited on Si(100) and Pt=T iO 2 =SiO 2 =Si substrates by a chemical method and crystallized in electric furnace at 700 deg C for 1 hour. The effects of substrate, pyrolysis temperature and excess lead addition in the films are reported. For films with 10 mol% PbO in excess, the pyrolysis in the regime of 300 deg C for 30 minutes was observed to yield PZT pyrochlore free thin films deposited on Pt=T iO 2 =SiO 2 =Si substrate. Out this condition, the transformation from amorphous to the pyrochlore metastable phase is kinetically more favorable that a transformation to the perovskite phase, which is thermodynamically stable. Rietveld refinements based on X-ray diffraction results showed that films present a purely tetragonal phase and that this phase does not change when the film thickness decreases. The dielectric permittivity measurements showed a monoclinic → tetragonal phase transition at 198K. Results showed that the dielectric permittivity (ε) increases continuously from 257 to 463, while the thickness of the PZT films increases from 200 to 710 nm. These results suggests that interface pinning centers can be the responsible mechanism by

  18. Theoretical study of ferroelectric nanoparticles using phase reconstructed electron microscopy

    DEFF Research Database (Denmark)

    Phatak, C.; Petford-Long, A. K.; Beleggia, Marco

    2014-01-01

    Ferroelectric nanostructures are important for a variety of applications in electronic and electro-optical devices, including nonvolatile memories and thin-film capacitors. These applications involve stability and switching of polarization using external stimuli, such as electric fields. We prese...

  19. Properties of epitaxial ferroelectric PbZr0.56Ti0.44O3 heterostructures with La0.5Sr0.5CoO3 metallic oxide electrodes

    International Nuclear Information System (INIS)

    Wang, F.; Leppaevuori, S.

    1997-01-01

    PbZr 0.56 Ti 0.44 O 3 (PZT) epitaxial ferroelectric thin films on a LaAlO 3 (100) substrate, covered by a metallic oxide electrode La 0.5 Sr 0.5 CoO 3 (LSCO) are demonstrated in this work. The films are fabricated by the sol endash gel method and effort was focused on thermal processing to obtain the desired epitaxial heterostructure. The dielectric and ferroelectric properties of PZT thin films were measured and it was found that they are as good as in the films deposited by other thin-film methods. The dielectric constant and the dissipation factor of the PZT films are, respectively, about 500 and 0.06 below 20 kHz. The remanent polarization P r is about 27 μC/cm 2 and the coercive field E c is about 50 kV/cm. It was found that the ferroelectric properties were significantly influenced by the microstructure of the PZT layers. The present study also showed that the fatigue characteristics of the epitaxial heterostructure with LSCO electrodes under a reversed electrical field are far superior to those obtained with a polycrystalline ferroelectric layer on Pt bottom electrodes. A low leakage current, about 3 μA/cm 2 at 0.5 MV/cm, was obtained for these epitaxial films. In addition, the optical transmittance spectrum of PZT thin films was also measured and the conduction mechanism is discussed.copyright 1997 American Institute of Physics

  20. Controlling dielectric and relaxor-ferroelectric properties for energy storage by tuning Pb0.92La0.08Zr0.52Ti0.48O3 film thickness.

    Science.gov (United States)

    Brown, Emery; Ma, Chunrui; Acharya, Jagaran; Ma, Beihai; Wu, Judy; Li, Jun

    2014-12-24

    The energy storage properties of Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films grown via pulsed laser deposition were evaluated at variable film thickness of 125, 250, 500, and 1000 nm. These films show high dielectric permittivity up to ∼1200. Cyclic I-V measurements were used to evaluate the dielectric properties of these thin films, which not only provide the total electric displacement, but also separate contributions from each of the relevant components including electric conductivity (D1), dielectric capacitance (D2), and relaxor-ferroelectric domain switching polarization (P). The results show that, as the film thickness increases, the material transits from a linear dielectric to nonlinear relaxor-ferroelectric. While the energy storage per volume increases with the film thickness, the energy storage efficiency drops from ∼80% to ∼30%. The PLZT films can be optimized for different energy storage applications by tuning the film thickness to optimize between the linear and nonlinear dielectric properties and energy storage efficiency.

  1. Flexoelectricity: strain gradient effects in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Ma Wenhui [Department of Physics, Shantou Unversity, Shantou, Guangdong 515063 (China)

    2007-12-15

    Mechanical strain gradient induced polarization effect or flexoelectricity in perovskite-type ferroelectric and relaxor ferroelectric ceramics was investigated. The flexoelectric coefficients measured at room temperature ranged from about 1 {mu} C m{sup -1} for lead zirconate titanate to 100 {mu} C m{sup -1} for barium strontium titanate. Flexoelectric effects were discovered to be sensitive to chemical makeup, phase symmetry, and domain structures. Based on phenomenological discussion and experimental data on flexoelectricity, the present study proposed that mechanical strain gradient field could influence polarization responses in a way analogous to electric field. Flexoelectric coefficients were found to be nonlinearly enhanced by dielectric permittivity and strain gradient. Interfacial mismatch in epitaxial thin films can give rise to high strain gradients, enabling flexoelectric effects to make a significant impact in properly engineered ferroelectric heterostructure systems.

  2. Preparation and switching kinetics of Pb(Zr, Ti)O sub 3 thin films deposited by reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hase, Takashi; Shiosaki, Tadashi [Kyoto Univ. (Japan). Faculty of Engineering

    1991-09-01

    Ferroelectric Pb(Zr, Ti)O{sub 3} (PZT) thin films have been prepared on Pt/Ti/SiO{sub 2}/Si and Pt/SiO{sub 2}/Si substrates using the reactive sputtering method with a metal composite target. The (111)-oriented PZT (80/20) thin films with a perovskite structure have been obtained at a substrate temperature of 595degC on highly (111)-oriented Pt films formed on SiO{sub 2}/Si substrates. When an 8 V pulse sequence was applied to a 265 nm-thick film with an electrode area of 50 x 50 {mu}m{sup 2}, the switching time and the switched charge density measured were 20 ns and 10 {mu}C/cm{sup 2}, respectively. The switching time was strongly dependent on the electrode area. (author).

  3. The origin of the residual conductivity of GaN films on ferroelectric materials

    Science.gov (United States)

    Lee, Kyoung-Keun; Cai, Zhuhua; Ziemer, Katherine; Doolittle, William Alan

    2009-08-01

    In this paper, the origin of the conductivity of GaN films grown on ferroelectric materials was investigated using XPS, AES, and XRD analysis tools. Depth profiles confirmed the existence of impurities in the GaN film originating from the substrates. Bonding energy analysis from XPS and AES verified that oxygen impurities from the substrates were the dominant origin of the conductivity of the GaN film. Furthermore, Ga-rich GaN films have a greater chance of enhancing diffusion of lithium oxide from the substrates, resulting in more substrate phase separation and a wider inter-mixed region confirmed by XRD. Therefore, the direct GaN film growth on ferroelectric materials causes impurity diffusion from the substrates, resulting in highly conductive GaN films. Future work needs to develop non-conductive buffer layers for impurity suppression in order to obtain highly resistive GaN films.

  4. Preparation of PZT/YBCO/YAlO heterostructure thin films by KrF excimer laser ablation

    International Nuclear Information System (INIS)

    Ebihara, Kenji; Kurogi, Hiromitsu; Yamagata, Yukihiko; Ikegami, Tomoaki; Grishin, A.M.

    1998-01-01

    The perovskite oxide YBa 2 Cu 3 O 7-x (YBCO) and Pb(Zr x Ti 1-x )O 3 (PZT) thin films have been deposited for superconducting-ferroelectric devices. KrF excimer laser ablation technique was used at the deposition conditions of 200--600 mTorr O 2 , 2-3J/cm 2 and 5--10 Hz operation frequency. Heterostructures of PZT-YBCO-YAlO 3 :Nd show the zero resistivity critical temperature of 82 K and excellent ferroelectric properties of remnant polarization 32 microC/cm 2 , coercive force of 80 kV/cm and dielectric constant 800. Cycling fatigue characteristics and leakage current are also discussed

  5. Characterization of Phase Transitions in PZT Ferroelectric films with spectral Ellipsometry

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Suchaneck, G.; Jastrabík, Lubomír; Gerlach, G.

    11-12, - (2002), s. 377-380 ISSN 0447-6441 R&D Projects: GA MŠk LN00A015; GA ČR GA202/00/1425 Institutional research plan: CEZ:AV0Z1010921 Keywords : ferroelectric film * phase transition * film profile Subject RIV: BH - Optics, Masers, Lasers

  6. Thick-film processing of Pb5Ge3O11-based ferroelectric glass-ceramics

    International Nuclear Information System (INIS)

    Cornejo, I.A.; Haun, M.J.

    1996-01-01

    Processing techniques were investigated to produce c-axis orientation, or texture, of ferroelectric Pb 5 Ge 3 O 11 -based glass-ceramic compositions during crystallization of amorphous thick-film printed samples from the Pb 5 Ge 3 O 11 -PbTiO 3 (PG-PT) and Pb 5 Ge 3 O 11 -Pb(Zr 1/2 Ti 1/2 )O 3 (PG-PZT) systems. In these systems the PG crystallized into a ferroelectric phase, producing a multiple ferroelectric phase composite at low temperatures, PG-PT or PG-PZT. In this way the non-ferroelectric component of traditional ferroelectric glass-ceramics was eliminated

  7. Supercapacitors: Ferroelectric Polymer-Ceramic Nanoparticle Composite Films for Use in the Capacitive Storage of Electrical Energy

    Science.gov (United States)

    Parsons, Dana; Pierce, Andrew; Porter, Tim; Dillingham, Randy; Cornelison, David

    2010-03-01

    Most new alternative energy solutions including wind and solar power, will require short term energy storage for widespread implementation. One means of storage would be the use of capacitors owing to their rapid delivery of power and longevity compared to chemical batteries. Capacitor materials exhibiting high dielectric permittivity and breakdown strength, as well as light weight and environmental safety are most desirable. Recently, new classes of capacitor dielectric materials, consisting of ferroelectric polymer matrices containing ceramic nanoparticles have attracted renewed interest due to their high potential energy storage, charge and discharge properties and lightweight. In this study, polyvinylidene flouride (PVDF) thin films containing nanoparticles of the ceramic titanium dioxide created using a physical vapor deposition process, are analyzed for use as dielectrics for a supercapacitor. Measured results of the film parameters including dielectric properties and breakdown voltages will be presented. These parameters will be analyzed with respect to film characteristics such as, dispersion of the ceramic particles, thickness of the films and composition ratios.

  8. Multistate storage nonvolatile memory device based on ferroelectricity and resistive switching effects of SrBi2Ta2O9 films

    Science.gov (United States)

    Song, Zhiwei; Li, Gang; Xiong, Ying; Cheng, Chuanpin; Zhang, Wanli; Tang, Minghua; Li, Zheng; He, Jiangheng

    2018-05-01

    A memory device with a Pt/SrBi2Ta2O9(SBT)/Pt(111) structure was shown to have excellent combined ferroelectricity and resistive switching properties, leading to higher multistate storage memory capacity in contrast to ferroelectric memory devices. In this device, SBT polycrystalline thin films with significant (115) orientation were fabricated on Pt(111)/Ti/SiO2/Si(100) substrates using CVD (chemical vapor deposition) method. Measurement results of the electric properties exhibit reproducible and reliable ferroelectricity switching behavior and bipolar resistive switching effects (BRS) without an electroforming process. The ON/OFF ratio of the resistive switching was found to be about 103. Switching mechanisms for the low resistance state (LRS) and high resistance state (HRS) currents are likely attributed to the Ohmic and space charge-limited current (SCLC) behavior, respectively. Moreover, the ferroelectricity and resistive switching effects were found to be mutually independent, and the four logic states were obtained by controlling the periodic sweeping voltage. This work holds great promise for nonvolatile multistate memory devices with high capacity and low cost.

  9. Crystallization and electrical characteristics of ferroelectric Bi{sub 3.15}Nd{sub 0.85}Ti{sub 3}O{sub 12} thin films prepared by a sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Y. [Department of Physics, Jianghan University, Wuhan 430056 (China); Department of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Lu, C.J. [Department of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China)], E-mail: chaojing_lu@yahoo.com; Qi, Y.J. [Department of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Zhou, Y.H. [Department of Physics, Jianghan University, Wuhan 430056 (China)

    2008-07-01

    Ferroelectric Bi{sub 3.15}Nd{sub 0.85}Ti{sub 3}O{sub 12} (BNdT) thin films were deposited on Pt/Ti/SiO{sub 2}/Si substrates using a sol-gel process and Bi(NO{sub 3}){sub 3} was used as one of starting materials. Upon heating the major weight loss of the wet films occurred below 320 deg. C and nitrogen was almost completely removed at 650 deg. C. The films began to crystallize around 520 deg. C. The films annealed at 750 deg. C contain grains of 50-100 nm in diameter. The BNdT film capacitors with Pt top electrodes exhibited well-saturated hysteresis loops with a remanent polarization (2P{sub r}) of 57.4 {mu}C/cm{sup 2} and a coercive field of 108.3 kV/cm. The Pt/BNdT/Pt capacitors did not show any significant fatigue up to 6x10{sup 10} read/write switching cycles, and the retained charges remained nearly constant up to 10{sup 4} s after applying a writing pulse. The leakage current density of the BNdT films is less than 5x10{sup -8} A/cm{sup 2} under a low external field below 73 kV/cm.

  10. The effects of strain relaxation on the dielectric properties of epitaxial ferroelectric Pb(Zr0.2Ti0.8)TiO3 thin films

    Science.gov (United States)

    Khan, Asif Islam; Yu, Pu; Trassin, Morgan; Lee, Michelle J.; You, Long; Salahuddin, Sayeef

    2014-07-01

    We study the effects of strain relaxation on the dielectric properties of epitaxial 40 nm Pb(Zr0.2Ti0.8)TiO3 (PZT) films. A significant increase in the defect and dislocation density due to strain relaxation is observed in PZT films with tetragonality c/a fatigue in ferroelectric materials.

  11. Polarized Raman scattering study of PSN single crystals and epitaxial thin films

    Directory of Open Access Journals (Sweden)

    J. Pokorný

    2015-06-01

    Full Text Available This paper describes a detailed analysis of the dependence of Raman scattering intensity on the polarization of the incident and inelastically scattered light in PbSc0.5Nb0.5O3 (PSN single crystals and epitaxially compressed thin films grown on (100-oriented MgO substrates. It is found that there are significant differences between the properties of the crystals and films, and that these differences can be attributed to the anticipated structural differences between these two forms of the same material. In particular, the scattering characteristics of the oxygen octahedra breathing mode near 810 cm-1 indicate a ferroelectric state for the crystals and a relaxor state for the films, which is consistent with the dielectric behaviors of these materials.

  12. Structural and dielectric properties of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin films grown by PLD

    Energy Technology Data Exchange (ETDEWEB)

    James, K. K.; Satish, B.; Jayaraj, M. K. [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kerala (India)

    2014-01-28

    Ferroelectric thin films of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} (BST) were deposited on Si/SiO{sub 2}/TiO{sub 2}/Pt (PtSi) substrate by pulsed laser deposition (PLD). Crystalline films with perovskite structure were obtained without post-deposition annealing. Phase purity of the deposited films was confirmed by x-ray diffraction. The lowest value of FWHM obtained for the film deposited at oxygen pressure 5.4×10{sup −4} mbar and substrate temperature 600°C, indicates the high crystallinity of the film. The room temperature dielectric constant at 100 kHz was 85. Butterfly loop, which is the characteristic of ferroelectric materials, was obtained in the regime of −4 to +4V. The leakage current density was nearly 9×10{sup −13} Acm{sup −2}.

  13. Room-Temperature Multiferroics and Thermal Conductivity of 0.85BiFe1-2xTixMgxO3-0.15CaTiO3 Epitaxial Thin Films (x = 0.1 and 0.2).

    Science.gov (United States)

    Zhang, Ji; Sun, Wei; Zhao, Jiangtao; Sun, Lei; Li, Lei; Yan, Xue-Jun; Wang, Ke; Gu, Zheng-Bin; Luo, Zhen-Lin; Chen, Yanbin; Yuan, Guo-Liang; Lu, Ming-Hui; Zhang, Shan-Tao

    2017-08-02

    Thin films of 0.85BiFe 1-2x Ti x Mg x O 3 -0.15CaTiO 3 (x = 0.1 and 0.2, abbreviated to C-1 and C-2, respectively) have been fabricated on (001) SrTiO 3 substrate with and without a conductive La 0.7 Sr 0.3 MnO 3 buffer layer. The X-ray θ-2θ and ϕ scans, atomic force microscopy, and cross-sectional transmission electron microscopy confirm the (001) epitaxial nature of the thin films with very high growth quality. Both the C-1 and C-2 thin films show well-shaped magnetization-magnetic field hysteresis at room temperature, with enhanced switchable magnetization values of 145.3 and 42.5 emu/cm 3 , respectively. The polarization-electric loops and piezoresponse force microscopy measurements confirm the room-temperature ferroelectric nature of both films. However, the C-1 films illustrate a relatively weak ferroelectric behavior and the poled states are easy to relax, whereas the C-2 films show a relatively better ferroelectric behavior with stable poled states. More interestingly, the room-temperature thermal conductivity of C-1 and C-2 films are measured to be 1.10 and 0.77 W/(m·K), respectively. These self-consistent multiferroic properties and thermal conductivities are discussed by considering the composition-dependent content and migration of Fe-induced electrons and/or charged point defects. This study not only provides multifunctional materials with excellent room-temperature magnetic, ferroelectric, and thermal conductivity properties but may also stimulate further work to develop BiFeO 3 -based materials with unusual multifunctional properties.

  14. Low temperature formation of ferroelectric PbTiO3 films by laser ablation with 2nd laser irradiation; Reiki hikari laser heiyo laser ablation ho ni yoru kyoyudentai PbTiO3 usumaku no teion keisei

    Energy Technology Data Exchange (ETDEWEB)

    Tabata, H.; Kawai, T. [Osaka University, Osaka (Japan)

    1997-08-20

    The unique advantage of the pulsed laser deposition is its ability to produce highly oriented stoichiometric films at a low substrate temperature. Ferroelectric PbTiO3 thin films have been formed using 2nd laser assisted laser ablaion technique at low temperature, i.e., 350degC, on Sr7iO3 single-crystal substrates and Pt/MgO electrodes. The second laser irradiation at the substrate surface is quite effective for crystallization of the films at low substrate temperature below 400degC. The suitable energy density (fluence) of the irradiation laser is in the range of 30-100 mJ/cm{sup 2}. X-ray diffraction patterns of PbTiO3 thin films show c-axis orientation, with a rocking angle of 1.0 - 0.5deg. These films exhibit ferroelectric hysteresis loop. The dielectric constant and remanent polalyzation of the PbTiO3 films are in the range of 120-150 and 60-80 {mu}C/cm{sup 2}, respectively. 31 refs., 10 figs., 1 tab.

  15. Optical properties of self-polarized PZT ferroelectric films

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Jastrabík, Lubomír; Suchaneck, G.; Gerlach, G.

    2002-01-01

    Roč. 273, - (2002), s. 155-160 ISSN 0015-0193 R&D Projects: GA MŠk LN00A015; GA ČR GA202/00/1425 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferroelectric film * phase transition * band gap Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.408, year: 2002

  16. Structural transformation and multiferroic properties of single-phase Bi{sub 0.89}Tb{sub 0.11}Fe{sub 1−x}Mn{sub x}O{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guohua; Tan, Guoqiang, E-mail: tan3114@163.com; Luo, Yangyang; Liu, Wenlong; Ren, Huijun; Xia, Ao

    2014-01-30

    Pure BiFeO{sub 3} (BFO) and Tb, Mn co-doped BiFeO{sub 3} (BTFMO) thin films were deposited on SnO{sub 2}: F (FTO)/glass substrates using a chemical solution deposition method. Detailed investigations were made on the influence of (Tb, Mn) co-doping on the structure change and the electric properties of the BFO films. With the co-doping of Tb and Mn, the structural transformation from rhombohedral R3c to triclinic P1 is confirmed through XRD, Rietveld refinement and Raman analysis. XPS analysis clarifies that (Tb, Mn) co-doping avails to decrease oxygen vacancy concentration, showing less Fe{sup 2+} ions in the co-doped BTFMO thin films than that of the pure BFO thin film. Among the co-doped thin films, the BTFM{sub 1}O film shows the highly enhanced ferroelectric properties with a giant remnant polarization value (2P{sub r} = 180.3 μC/cm{sup 2}). The structural transformation, the well-distributed fine grains and the reduction of leakage current favor enhanced ferroelectric property of (Tb, Mn) co-doped BFO films. It is also found that the BTFM{sub 1}O film shows the enhanced ferromagnetism with the saturated magnetization (M{sub s} = 2.5 emu/cm{sup 3}) as a result of the collapse of space modulated spin structure by the structure transformation.

  17. Hybrid dual gate ferroelectric memory for multilevel information storage

    KAUST Repository

    Khan, Yasser

    2015-01-01

    Here, we report hybrid organic/inorganic ferroelectric memory with multilevel information storage using transparent p-type SnO semiconductor and ferroelectric P(VDF-TrFE) polymer. The dual gate devices include a top ferroelectric field-effect transistor (FeFET) and a bottom thin-film transistor (TFT). The devices are all fabricated at low temperatures (∼200°C), and demonstrate excellent performance with high hole mobility of 2.7 cm2 V-1 s-1, large memory window of ∼18 V, and a low sub-threshold swing ∼-4 V dec-1. The channel conductance of the bottom-TFT and the top-FeFET can be controlled independently by the bottom and top gates, respectively. The results demonstrate multilevel nonvolatile information storage using ferroelectric memory devices with good retention characteristics.

  18. Dielectric and ferroelectric properties of strain-relieved epitaxial lead-free KNN-LT-LS ferroelectric thin films on SrTiO3 substrates

    Science.gov (United States)

    Abazari, M.; Akdoǧan, E. K.; Safari, A.

    2008-05-01

    We report the growth of single-phase (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.10,Sb0.06)O3 thin films on SrRuO3 coated ⟨001⟩ oriented SrTiO3 substrates by using pulsed laser deposition. Films grown at 600°C under low laser fluence exhibit a ⟨001⟩ textured columnar grained nanostructure, which coalesce with increasing deposition temperature, leading to a uniform fully epitaxial highly stoichiometric film at 750°C. However, films deposited at lower temperatures exhibit compositional fluctuations as verified by Rutherford backscattering spectroscopy. The epitaxial films of 400-600nm thickness have a room temperature relative permittivity of ˜750 and a loss tangent of ˜6% at 1kHz. The room temperature remnant polarization of the films is 4μC /cm2, while the saturation polarization is 7.1μC/cm2 at 24kV/cm and the coercive field is ˜7.3kV/cm. The results indicate that approximately 50% of the bulk permittivity and 20% of bulk spontaneous polarization can be retained in submicron epitaxial KNN-LT-LS thin film, respectively. The conductivity of the films remains to be a challenge as evidenced by the high loss tangent, leakage currents, and broad hysteresis loops.

  19. Solid thin film materials for use in thin film charge-coupled devices

    International Nuclear Information System (INIS)

    Lynch, S.J.

    1983-01-01

    Solid thin films deposited by vacuum deposition were evaluated to ascertain their effectiveness for use in the manufacturing of charge-coupled devices (CCDs). Optical and electrical characteristics of tellurium and Bi 2 Te 3 solid thin films were obtained in order to design and to simulate successfully the operation of thin film (TF) CCDs. In this article some of the material differences between single-crystal material and the island-structured thin film used in TFCCDs are discussed. The electrical parameters were obtained and tabulated, e.g. the mobility, conductivity, dielectric constants, permittivity, lifetime of holes and electrons in the thin films and drift diffusion constants. The optical parameters were also measured and analyzed. After the design was complete, experimental TFCCDs were manufactured and were successfully operated utilizing the aforementioned solid thin films. (Auth.)

  20. Voltage-controlled ferroelastic switching in Pb(Zr.sub.0.2./sub.Ti.sub.0.8./sub.)O.sub.3./sub. thin films

    Czech Academy of Sciences Publication Activity Database

    Khan, A.I.; Martí, Xavier; Serrao, C.; Ramesh, R.; Salahuddin, S.

    2015-01-01

    Roč. 15, č. 4 (2015), s. 2229-2234 ISSN 1530-6984 Institutional support: RVO:68378271 Keywords : nanodomains * ferroelastic switching * ferroelectricity * Pb(Zr 0.2 Ti 0.8 )O 3 * thin film Subject RIV: BE - Theoretical Physics Impact factor: 13.779, year: 2015

  1. Thin-film photovoltaic technology

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, R.N. [National Renewable Energy Laboratory, Golden, CO (United States)

    2010-07-01

    The high material and processing costs associated with single-crystal and polycrystalline silicon wafers that are commonly used in photovoltaic cells render these modules expensive. This presentation described thin-film solar cell technology as a promising alternative to silicon solar cell technology. Cadmium telluride (CdTe) thin films along with copper, indium, gallium, and selenium (CIGS) thin films have become the leaders in this field. Their large optical absorption coefficient can be attributed to a direct energy gap that allows the use of thin layers (1-2 {mu}m) of active material. The efficiency of thin-film solar cell devices based on CIGS is 20 per cent, compared to 16.7 per cent for thin-film solar cell devices based on CdTe. IBM recently reported an efficiency of 9.7 per cent for a new type of inorganic thin-film solar cell based on a Cu{sub 2}ZnSn(S, Se){sub 4} compound. The efficiency of an organic thin-film solar cell is 7.9 per cent. This presentation included a graph of PV device efficiencies and discussed technological advances in non-vacuum deposited, CIGS-based thin-film solar cells. 1 fig.

  2. Nanoscale ferroelectrics and multiferroics key processes and characterization issues, and nanoscale effects

    CERN Document Server

    Alguero, Miguel

    2016-01-01

    This book reviews the key issues in processing and characterization of nanoscale ferroelectrics and multiferroics, and provides a comprehensive description of their properties, with an emphasis in differentiating size effects of extrinsic ones like boundary or interface effects. Recently described nanoscale novel phenomena are also addressed. Organized into three parts it addresses key issues in processing (nanostructuring), characterization (of the nanostructured materials) and nanoscale effects. Taking full advantage of the synergies between nanoscale ferroelectrics and multiferroics, it covers materials nanostructured at all levels, from ceramic technologies like ferroelectric nanopowders, bulk nanostructured ceramics and thick films, and magnetoelectric nanocomposites, to thin films, either polycrystalline layer heterostructures or epitaxial systems, and to nanoscale free standing objects with specific geometries, such as nanowires and tubes at different levels of development. The book is developed from t...

  3. Strain engineering of perovskite thin films using a single substrate

    International Nuclear Information System (INIS)

    Janolin, P-E; Guiblin, N; Dkhil, B; Anokhin, A S; Mukhortov, V M; Golovko, Yu I; Gui, Z; Bellaiche, L; Ravy, S; El Marssi, M; Yuzyuk, Yu I

    2014-01-01

    Combining temperature-dependent x-ray diffraction, Raman spectroscopy and first-principles-based effective Hamiltonian calculations, we show that varying the thickness of (Ba 0.8 Sr 0.2 )TiO 3 (BST) thin films deposited on the same single substrate (namely, MgO) enables us to change not only the magnitude but also the sign of the misfit strain. Such previously overlooked control of the strain allows several properties of these films (e.g. Curie temperature, symmetry of ferroelectric phases, dielectric response) to be tuned and even optimized. Surprisingly, such desired control of the strain (and of the resulting properties) originates from an effect that is commonly believed to be detrimental to functionalities of films, namely the existence of misfit dislocations. The present study therefore provides a novel route to strain engineering, as well as leading us to revisit common beliefs. (fast track communication)

  4. Ferroelectricity at the nanoscale basics and applications

    CERN Document Server

    Fridkin, Vladimir

    2014-01-01

    This book examines a wide range of ferroelectric materials. It explains the theoretical background of ultrathin ferroelectric films,  presents applications of ferroelectric materials, and displays the mechanism of switching of nanosized ferroelectric films.

  5. Bulk photovoltaic effect in epitaxial (K, Nb) substituted BiFeO3 thin films

    Science.gov (United States)

    Agarwal, Radhe; Zheng, Fan; Sharma, Yogesh; Hong, Seungbum; Rappe, Andrew; Katiyar, Ram

    We studied the bulk photovoltaic effect in epitaxial (K, Nb) modified BiFeO3 (BKFNO) thin films using theoretical and experimental methods. Epitaxial BKFNO thin films were grown by pulsed laser deposition (PLD). First, we have performed first principles density function theory (DFT) using DFT +U method to calculate electronic band structure, including Hubbard-Ueff (Ueff =U-J) correction into Hamiltonian. The electronic band structure calculations showed a direct band gap at 1.9 eV and a defect level at 1.7 eV (in a 40 atom BKFNO supercell), sufficiently lower in comparison to the experimentally observed values. Furthermore, the piezoforce microscopy (PFM) measurements indicated the presence of striped polydomains in BKFNO thin films. Angle-resolved PFM measurements were also performed to find domain orientation and net polarization directions in these films. The experimental studies of photovoltaic effect in BKNFO films showed a short circuit current of 59 micro amp/cm2 and open circuit voltage of 0.78 V. We compared our experimental results with first principles shift current theory calculations of bulk photovoltaic effect (BPVE).The synergy between theory and experimental results provided a realization of significant role of BPVE in order to understand the photovoltaic mechanism in ferroelectrics.

  6. Nonlinear piezoelectricity in epitaxial ferroelectrics at high electric fields.

    Science.gov (United States)

    Grigoriev, Alexei; Sichel, Rebecca; Lee, Ho Nyung; Landahl, Eric C; Adams, Bernhard; Dufresne, Eric M; Evans, Paul G

    2008-01-18

    Nonlinear effects in the coupling of polarization with elastic strain have been predicted to occur in ferroelectric materials subjected to high electric fields. Such predictions are tested here for a PbZr0.2Ti0.8O3 ferroelectric thin film at electric fields in the range of several hundred MV/m and strains reaching up to 2.7%. The piezoelectric strain exceeds predictions based on constant piezoelectric coefficients at electric fields from approximately 200 to 400 MV/m, which is consistent with a nonlinear effect predicted to occur at corresponding piezoelectric distortions.

  7. A theoretical investigation of the influence of the surface effect on the ferroelectric property of strained barium titanate film

    Science.gov (United States)

    Fang, Chao; Liu, Wei Hua

    2017-07-01

    The influence of the surface effect on the ferroelectric property of strained barium titanate film has been investigated. In this study, based on time-dependent Ginsburg-Landau-Devonshire thermodynamic theory, the surface effects have been simulated by introducing a surface constant, which leads to the strained BaTiO3 film consisting of inner tetragonal core and gradient lattice strain layer. Further, surface effects produce a depolarization field which has a dominant effect on the ferroelectric properties of the films. The spontaneous polarization, dielectric properties and ferroelectric hysteresis loop of BaTiO3 film are calculated under different boundary conditions. Theoretical and experimental results for strained BaTiO3 film are compared and discussed.

  8. Ferro electrical properties of GeSbTe thin films; Propiedades ferroelectricas de peliculas delgadas de GeSbTe

    Energy Technology Data Exchange (ETDEWEB)

    Gervacio A, J. J.; Prokhorov, E.; Espinoza B, F. J., E-mail: jgervacio@qro.cinvestav.m [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico)

    2011-07-01

    The aim of this work is to investigate and compare ferro electrical properties of thin GeSbTe films with composition Ge{sub 4}Sb{sub 1}Te{sub 5} (with well defined ferro electrical properties) and Ge{sub 2}Sb{sub 2}Te{sub 5} using impedance, optical reflection, XRD, DSc and Piezo response Force Microscopy techniques. The temperature dependence of the capacitance in both materials shows an abrupt change at the temperature corresponding to ferroelectric-paraelectric transition and the Curie-Weiss dependence. In Ge{sub 2}Sb{sub 2}Te{sub 5} films this transition corresponds to the end from a NaCl-type to a hexagonal transformation. Piezo response Force Microscopy measurements found ferroelectric domains with dimension approximately equal to the dimension of grains. (Author)

  9. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  10. Giant Polarization Rotation in BiFeO3/SrTiO3 Thin Films.

    Science.gov (United States)

    Langner, M. C.; Chu, Y. H.; Martin, L. M.; Gajek, M.; Ramesh, R.; Orenstein, J.

    2008-03-01

    We use optical second harmonic generation to probe dynamics of the ferroelectric polarization in (111) oriented BiFeO3 thin films grown on SrTiO3 substrates. The second harmonic response indicates 3m point group symmetry and is consistent with a spontaneous polarization normal to the surface of the film. We measure large changes in amplitude and lowering of symmetry, consistent with polarization rotation, when modest electric fields are applied in the plane of the film. At room temperature the rotation is an order of magnitude larger than expected from reported values of the dielectric constant and increases further (as 1/T) as temperature is lowered. We propose a substrate interaction model to explain these results.

  11. Studies on ion scattering and sputtering processes relevant to ion beam sputter deposition of multicomponent thin films

    International Nuclear Information System (INIS)

    Auciello, O.; Ameen, M.S.; Kingon, A.I.

    1989-01-01

    Results from computer simulation and experiments on ion scattering and sputtering processes in ion beam sputter deposition of high Tc superconducting and ferroelectric thin films are presented. It is demonstrated that scattering of neutralized ions from the targets can result in undesirable erosion of, and inert gas incorporation in, the growing films, depending on the ion/target atom ass ratio and ion beam angle of incidence/target/substrate geometry. The studies indicate that sputtering Kr + or Xe + ions is preferable to the most commonly used Ar + ions, since the undesirable phenomena mentioned above are minimized for the first two ions. These results are used to determine optimum sputter deposition geometry and ion beam parameters for growing multicomponent oxide thin films by ion beam sputter-deposition. 10 refs., 5 figs

  12. Microstructure evolution in pulsed laser deposited epitaxial Ge-Sb-Te chalcogenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Ulrich; Lotnyk, Andriy, E-mail: andriy.lotnyk@iom-leipzig.de; Thelander, Erik; Rauschenbach, Bernd

    2016-08-15

    The thin film deposition and structure of highly oriented telluride compounds is of particular interest for phase-change applications in next-generation non-volatile memory such as heterostructure designs, as well as for the investigation of novel optical, thermoelectric and ferroelectric properties in layered telluride compounds. In this work, epitaxial Ge-Sb-Te thin films were successfully produced by pulsed laser deposition on silicon with and without amorphous SiO{sub x} interlayer at elevated process temperatures from a Ge{sub 2}Sb{sub 2}Te{sub 5} target. Aberration-corrected high-resolution scanning transmission electron microscopy (STEM) imaging reveals a distinct interface configuration of the trigonal phase connected by a quasi van der Waals gap (vacancy) to the Sb/Te-passivated single crystalline Si substrate, yet also an intermediate textured growth regime in which the substrate symmetry is only weakly coupled to the thin film orientation, as well as strong deviation of composition at high deposition temperatures. Textured growth of Ge-Sb-Te thin film was also observed on SiO{sub x}/Si substrate with no evidence of an intermediate Sb/Te surface layer on top of an SiO{sub x} layer. In addition, particular defect structures formed by local reorganization of the stacking sequence across the vacancy gap are observed and appear to be intrinsic to these van der Waals-layered compounds. Theoretical image simulations of preferred stacking sequences can be matched to individual building blocks in the Ge-Sb-Te grain. - Highlights: • Atomic-resolution Cs-corrected STEM imaging of PLD deposited Ge-Sb-Te thin films. • Changing of overall composition with increasing deposition temperature. • Direct imaging of surface passivation Sb/Te layer at the Ge-Sb-Te/Si(111) interface. • The Sb/Te passivation layer is not a prerequisite for highly oriented growth of Ge-Sb-Te thin films.

  13. The thickness effect of Bi3.25La0.75Ti3O12 buffer layer in PbZr0.58Ti0.42O3/Bi3.25La0.75Ti3O12 (PZT/BLT) multilayered ferroelectric thin films

    International Nuclear Information System (INIS)

    Li Jianjun; Li Ping; Zhang Guojun; Yu Jun; Wu Yunyi; Wen Xinyi

    2011-01-01

    A series of PbZr 0.58 Ti 0.42 O 3 (PZT) thin films with various Bi 3.25 La 0.75 Ti 3 O 12 (BLT) buffer layer thicknesses were deposited on Pt/TiO 2 /SiO 2 /p-Si(100) substrates by RF magnetron sputtering. The X-ray diffraction measurements of PZT film and PZT/BLT multilayered films illustrate that the pure PZT film shows (111) preferential orientation, and the PZT/BLT films show (110) preferential orientation with increasing thickness of the BLT layer. There are no obvious diffraction peaks for the BLT buffer layer in the multilayered films, for interaction effect between the bottom BLT and top PZT films during annealing at the same time. From the surface images of field-emission scanning electron microscope, there are the maximum number of largest-size grains in PZT/BLT(30 nm) film among all the samples. The growth direction and grain size have significant effects on ferroelectric properties of the multilayered films. The fatigue characteristics of PZT and PZT/BLT films suggest that 30-nm-thick BLT is just an effective buffer layer enough to alleviate the accumulation of oxygen vacancies near the PZT/BLT interface. The comparison of these results with that of PZT/Pt/TiO 2 /SiO 2 /p-Si(100) basic structured film suggests that the buffer layer with an appropriate thickness can improve the ferroelectric properties of multilayered films greatly.

  14. Characterization Of Graphene-Ferroelectric Superlattice Hybrid Devices

    Science.gov (United States)

    Yusuf, Mohammed; Du, Xu; Dawber, Matthew

    2013-03-01

    Ferroelectric materials possess a spontaneous electrical polarization, which can be controlled by an electric field. A good interface between ferroelectric surface and graphene sheets can introduce a new generation of multifunctional devices, in which the ferroelectric material can be used to control the properties of graphene. In our approach, problems encountered in previous efforts to combine ferroelectric/carbon systems are overcome by the use of artificially layered superlattice materials grown in the form of epitaxial thin films. In these materials the phase transition temperature and dielectric response of the material can be tailored, allowing us to avoid polarization screening by surface absorbates, whilst maintaining an atomically smooth surface and optimal charge doping properties. Using ferroelectric PbTiO3/SrTiO3 superlattices, we have shown ultra-low-voltage operation of graphene field effect devices within +/- 1 V at room temperature. The switching of the graphene field effect transistors is characterized by pronounced resistance hysteresis, suitable for ultra-fast non-volatile electronics. Low temperature characterization confirmed that the coercive field required for the ferroelectric domain switching increases significantly with decreasing temperatures. National Science Foundation (NSF) (grant number 1105202)

  15. Sputtered highly oriented PZT thin films for MEMS applications

    Science.gov (United States)

    Kalpat, Sriram S.

    Recently there has been an explosion of interest in the field of micro-electro-mechanical systems (MEMS). MEMS device technology has become critical in the growth of various fields like medical, automotive, chemical, and space technology. Among the many applications of ferroelectric thin films in MEMS devices, microfluidics is a field that has drawn considerable amount of research from bio-technology industries as well as chemical and semiconductor manufacturing industries. PZT thin films have been identified as best suited materials for micro-actuators and micro-sensors used in MEMS devices. A promising application for piezoelectric thin film based MEMS devices is disposable drug delivery systems that are capable of sensing biological parameters, mixing and delivering minute and precise amounts of drugs using micro-pumps or micro mixers. These devices call for low driving voltages, so that they can be battery operated. Improving the performance of the actuator material is critical in achieving battery operated disposal drug delivery systems. The device geometry and power consumption in MEMS devices largely depends upon the piezoelectric constant of the films, since they are most commonly used to convert electrical energy into a mechanical response of a membrane or cantilever and vice versa. Phenomenological calculation on the crystal orientation dependence of piezoelectric coefficients for PZT single crystal have reported a significant enhancement of the piezoelectric d33 constant by more than 3 times along [001] in the rhombohedral phase as compared to the conventionally used orientation PZT(111) since [111] is the along the spontaneous polarization direction. This could mean considerable improvement in the MEMS device performance and help drive the operating voltages lower. The motivation of this study is to investigate the crystal orientation dependence of both dielectric and piezoelectric coefficients of PZT thin films in order to select the appropriate

  16. A Review of Domain Modelling and Domain Imaging Techniques in Ferroelectric Crystals

    Directory of Open Access Journals (Sweden)

    John E. Huber

    2011-02-01

    Full Text Available The present paper reviews models of domain structure in ferroelectric crystals, thin films and bulk materials. Common crystal structures in ferroelectric materials are described and the theory of compatible domain patterns is introduced. Applications to multi-rank laminates are presented. Alternative models employing phase-field and related techniques are reviewed. The paper then presents methods of observing ferroelectric domain structure, including optical, polarized light, scanning electron microscopy, X-ray and neutron diffraction, atomic force microscopy and piezo-force microscopy. Use of more than one technique for unambiguous identification of the domain structure is also described.

  17. Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

    International Nuclear Information System (INIS)

    Kurogi, H.; Yamagata, Y.; Ebihara, K.

    1998-01-01

    Pb(Zr X Ti 1-X )O 3 (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, λ=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm -2 on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P r =15 μC cm -2 , 30 μC cm -2 and E c =200 kV cm -1 , 100 kV cm -1 for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10 8 cycles of switching. (orig.)

  18. Effects of heat-treatment conditions on electrical properties of sol-gel-derived ferroelectric Pb(Zr,Ti)O3 thin films

    International Nuclear Information System (INIS)

    Shim, Donghyun; Pak, Jaemoon; Nam, Kuangwoo; Park, Gwangseo

    2005-01-01

    Pb(Zr,Ti)O 3 (PZT) films with Zr/Ti ratio of 50 : 50 were prepared by spin-casting at 3000 rpm for 30 sec on Pt/Ti/SiO 2 /Si substrates. After standard processing procedure, three different methods of annealing were conducted at 600 .deg. C : a single-step process carried out in (a) air, and (b) O 2 ambient, and (c) a 2-step process carried out in air, followed by an O 2 annealing process. These films were highly oriented along the (111) direction with large remnant polarization and low coercive voltage values. The films treated in O 2 had relatively larger polarization values, but the 2-step-annealed films possessed lower coercive voltage. Fatigue measurements were conducted until 1 X 10 10 switching cycles, resulting in abnormal switching characteristics for these films. A comparative study on the ferroelectric and fatigue properties will be emphasized.

  19. Analysis of multiferroic properties in BiMnO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Grizalez, M [Universidad de la Amazonia, Florencia (Colombia); Mendoza, G A [Department of Physics, Universidad Nacional de Colombia, Bogota (Colombia); Prieto, P, E-mail: pprieto@calima.univalle.edu.c [Center of Excellence on Novel Materials - CENM (Colombia)

    2009-05-01

    Textured BiMnO{sub 3} [111] thin films on SrTiO{sub 3} (100) and Pt/TiO{sub 2}/SiO{sub 2} substrates were grown via r.f. magnetron sputtering (13.56 MHz). The XRD spectra confirmed a monoclinic structure and high-quality textured films for the BiMnO{sub 3} films. The films grown on SrTiO{sub 3} (100) showed higher crystalline quality than those developed on Pt/TiO{sub 2}/SiO{sub 2}. Through optimized oxygen pressure of 5x10{sup -2} mbar during the r.f. sputtering deposition, the crystalline orientation of the BiMnO{sub 3} film was improved with respect to the previously reported value of 2x10{sup -1} mbar. The values of spontaneous polarization (P{sub s}), remnant polarization (P{sub r}), and coercive field (F{sub c}) from ferroelectric hysteresis loops (P-E) at different temperatures were also obtained. Samples with higher crystalline order revealed better dielectric properties (high P{sub s} and P{sub r} values and a low F{sub c}). For films on both types of substrates, the ferroelectric behavior was found to persist up to 400K. Measurements at higher temperatures were difficult to obtain given the increased conductivity of the films. Magnetic hysteresis loops from 5K to 120K were obtained for BiMnO{sub 3} films grown on SrTiO{sub 3} and Pt/TiO{sub 2}/SiO{sub 2} substrates. The results suggested that the coexistence of the magnetic and electric phases persists up to 120K.

  20. Reversible pyroelectric and photogalvanic current in epitaxial Pb(Zr0.52Ti0.48)O3 thin films

    Science.gov (United States)

    Lee, J.; Esayan, S.; Prohaska, J.; Safari, A.

    1994-01-01

    The pyroelectric and photogalvanic effects have been studied in epitaxial Pb(Zr0.52Ti0.48)O3 (PZT) thin films. Photoinduced currents, which were completely reversible by electrical voltage, were observed. The photoinduced currents exhibited transient and steady state components. The transient component, in turn, consisted of two components with fast (<1 s) and slow (˜hours) relaxation times. The mechanisms of the photoinduced currents in PZT films and their possible applications in nondestructive readout ferroelectric memory are discussed.

  1. Two-dimensional ferroelectric topological insulators in functionalized atomically thin bismuth layers

    Science.gov (United States)

    Kou, Liangzhi; Fu, Huixia; Ma, Yandong; Yan, Binghai; Liao, Ting; Du, Aijun; Chen, Changfeng

    2018-02-01

    We introduce a class of two-dimensional (2D) materials that possess coexisting ferroelectric and topologically insulating orders. Such ferroelectric topological insulators (FETIs) occur in noncentrosymmetric atomic layer structures with strong spin-orbit coupling (SOC). We showcase a prototype 2D FETI in an atomically thin bismuth layer functionalized by C H2OH , which exhibits a large ferroelectric polarization that is switchable by a ligand molecule rotation mechanism and a strong SOC that drives a band inversion leading to the topologically insulating state. An external electric field that switches the ferroelectric polarization also tunes the spin texture in the underlying atomic lattice. Moreover, the functionalized bismuth layer exhibits an additional quantum order driven by the valley splitting at the K and K' points in the Brillouin zone stemming from the symmetry breaking and strong SOC in the system, resulting in a remarkable state of matter with the simultaneous presence of the quantum spin Hall and quantum valley Hall effect. These phenomena are predicted to exist in other similarly constructed 2D FETIs, thereby offering a unique quantum material platform for discovering novel physics and exploring innovative applications.

  2. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  3. Fluoride Thin Films: from Exchange Bias to Multferroicity

    Science.gov (United States)

    Johnson, Trent A.

    This dissertation concerns research into the growth and characterization fluoride thin films by molecular beam epitaxy. After a discussion of relevant background material and experimental procedures in the first two chapters, we study exchange bias in magnetic multilayers incorporating the uniaxial antiferromagnet FeF2, grown to varying thicknesses, sandwiched between ferromagnetic Co layers with fixed thicknesses of 5 and 20 nm. Several bilayers with only the 20 nm thick Co layer were grown for comparative study. The samples were grown on Al2O3 (112¯0) substrates at room temperature. In-situ RHEED and x-ray diffraction indicated the films were polycrystalline. The films were determined to have low surface and interlayer roughness, as determined by AFM and x-ray reflectivity. After field-cooling to below the Neel temperature of FeF2 in a magnetic field of 1 kOe, magnetic hysteresis loops were measured as a function of temperature. We found that both layers had a negative exchange bias, with the exchange bias of the thinner layer larger than that of the thicker layer. In addition, the coercivity below the blocking temperature TB of the thinner layer was significantly larger than that of the thick layer, even though the coercivity of the two layers was the same for T > TB. The exchange bias effect, manifested by a shift in these hysteresis loops, showed a strong dependence on the thickness of the antiferromagnet. Anisotropic magnetoresistance measurements provided additional insight into the magnetization reversal mechanism within the ferromagnets. The thickness dependent exchange anisotropy of trilayer and bilayer samples is explained by adapting a random field model to the antiferromagnet/ferromagnet interface. Finally, We investigate the temperature dependent growth, as well as the magnetic and ferroelectric properties of thin films of the multiferroic compounds BaMF4, where M = Fe, Co, Ni. The films were grown to thicknesses of 50 or 100 nm on single crystal Al2

  4. Thin PZT-Based Ferroelectric Capacitors on Flexible Silicon for Nonvolatile Memory Applications

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-04-24

    A flexible version of traditional thin lead zirconium titanate ((Pb1.1Zr0.48Ti0.52O3)-(PZT)) based ferroelectric random access memory (FeRAM) on silicon shows record performance in flexible arena. The thin PZT layer requires lower operational voltages to achieve coercive electric fields, reduces the sol-gel coating cycles required (i.e., more cost-effective), and, fabrication wise, is more suitable for further scaling of lateral dimensions to the nano-scale due to the larger feature size-to-depth aspect ratio (critical for ultra-high density non-volatile memory applications). Utilizing the inverse proportionality between substrate\\'s thickness and its flexibility, traditional PZT based FeRAM on silicon is transformed through a transfer-less manufacturable process into a flexible form that matches organic electronics\\' flexibility while preserving the superior performance of silicon CMOS electronics. Each memory cell in a FeRAM array consists of two main elements; a select/access transistor, and a storage ferroelectric capacitor. Flexible transistors on silicon have already been reported. In this work, we focus on the storage ferroelectric capacitors, and report, for the first time, its performance after transformation into a flexible version, and assess its key memory parameters while bent at 0.5 cm minimum bending radius.

  5. thin films

    Indian Academy of Sciences (India)

    microscopy (SEM) studies, respectively. The Fourier transform ... Thin films; chemical synthesis; hydrous tin oxide; FTIR; electrical properties. 1. Introduction ... dehydrogenation of organic compounds (Hattori et al 1987). .... SEM images of (a) bare stainless steel and (b) SnO2:H2O thin film on stainless steel substrate at a ...

  6. Sol-gel reaction stability studied: Influence in the formation temperature and properties of ferroelectric thin films

    International Nuclear Information System (INIS)

    Perez, J.; Vilarinho, P.M.; Kholkin, A.L.; Almeida, A.

    2009-01-01

    Lead zirconium titanate (PZT) sol-gel solutions were prepared based on distilled lead acetate precursor solutions. A detailed analysis of the distillation effect on the lead precursor and the final PZT solution were carried out by Infrared and Raman techniques. It was found that the increase in the number of distillation steps experienced by the lead precursor solutions removes the constitutional water and increases the lead acetate-2-methoxyethanol interconnectivity; thus improving stability and avoiding the aging effect of the resulting PZT solutions. The thermal decomposition process of the PZT solutions was analyzed based on the thermogravimetric (TG) and differential thermogravimetric analysis (DTA) measurements. It was found that as the number of distillation steps in the lead precursor solutions increases, the decomposition rate increases and the formation temperature of pure perovskite PZT films decreases. X-ray diffraction (XRD) technique was used to study the film phase formation. A pure perovskite phase at 500 deg. C was found by the XRD analysis after the second distillation step. Scanning electron microscope technique was used to carry out the microstructural analysis. Dense microstructure was found in all analyzed films and an incipient columnar grain growth was revealed in PZT films prepared based on lead precursor solution with more than three distillation steps. The dependence of the dielectric, ferroelectric and piezoelectric properties on the number of distillation steps was revealed and a correlation between the distillation process, film microstructure properties and electrical performance was established

  7. Influence of test capacitor features on piezoelectric and dielectric measurement of ferroelectric films.

    Science.gov (United States)

    Wang, Zhihong; Lau, Gih Keong; Zhu, Weiguang; Chao, Chen

    2006-01-01

    This paper presents both theoretical and numerical analyses of the piezoelectric and dielectric responses of a highly idealized film-on-substrate system, namely, a polarized ferroelectric film perfectly bonded to an elastic silicon substrate. It shows that both effective dielectric and piezoelectric properties of the films change with the size and configuration of the test capacitor. There exists a critical electrode size that is smaller than the diameter of the commonly used substrate. The effective film properties converge to their respective constrained values as capacitor size increases to the critical size. If capacitor size is smaller than the critical size, the surface displacement at the top electrode deviates from the net thickness change in response to an applied voltage because the film is deformable at the film/substrate interface. The constrained properties of the films depend only on those of bulk ferroelectrics but are independent of film thickness and substrate properties. The finding of the critical capacitor size together with analytical expressions of the constrained properties makes it possible to realize consistent measurement of piezoelectric and dielectric properties of films. A surface scanning technique is recommended to measure the profile of piezoresponses of the film so that the constrained properties of the film can be identified accurately.

  8. Mn 3d bands and Y–O hybridization of hexagonal and orthorhombic YMnO.sub.3./sub. thin films

    Czech Academy of Sciences Publication Activity Database

    Martins, H.P.; Mossanek, R.J.O.; Martí, Xavier; Sánchez, F.; Fontcuberta, J.; Abbate, M.

    2017-01-01

    Roč. 29, č. 29 (2017), s. 1-6, č. článku 295501. ISSN 0953-8984 Institutional support: RVO:68378271 Keywords : YMnO 3 thin films * x-ray absorption * band structure calculations * ferroelectricity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.649, year: 2016

  9. Effect of ZnO channel thickness on the device behaviour of nonvolatile memory thin film transistors with double-layered gate insulators of Al2O3 and ferroelectric polymer

    International Nuclear Information System (INIS)

    Yoon, Sung-Min; Yang, Shin-Hyuk; Ko Park, Sang-Hee; Jung, Soon-Won; Cho, Doo-Hee; Byun, Chun-Won; Kang, Seung-Youl; Hwang, Chi-Sun; Yu, Byoung-Gon

    2009-01-01

    Poly(vinylidene fluoride trifluoroethylene) and ZnO were employed for nonvolatile memory thin film transistors as ferroelectric gate insulator and oxide semiconducting channel layers, respectively. It was proposed that the thickness of the ZnO layer be carefully controlled for realizing the lower programming voltage, because the serially connected capacitor by the formation of a fully depleted ZnO channel had a critical effect on the off programming voltage. The fabricated memory transistor with Al/P(VDF-TrFE) (80 nm)/Al 2 O 3 (4 nm)/ZnO (5 nm) exhibits encouraging behaviour such as a memory window of 3.8 V at the gate voltage of -10 to 12 V, and 10 7 on/off ratio, and a gate leakage current of 10 -11 A.

  10. Thin Film Microbatteries

    International Nuclear Information System (INIS)

    Dudney, Nancy J.

    2008-01-01

    Thin film batteries are built layer by layer by vapor deposition. The resulting battery is formed of parallel plates, much as an ordinary battery construction, just much thinner. The figure (Fig. 1) shows an example of a thin film battery layout where films are deposited symmetrically onto both sides of a supporting substrate. The full stack of films is only 10 to 15 (micro)m thick, but including the support at least doubles the overall battery thickness. When the support is thin, the entire battery can be flexible. At least six companies have commercialized or are very close to commercializing such all-solid-state thin film batteries and market research predicts a growing market and a variety of applications including sensors, RFID tags, and smarter cards. In principle with a large deposition system, a thin film battery might cover a square meter, but in practice, most development is targeting individual cells with active areas less than 25 cm 2 . For very small battery areas, 2 , microfabrication processes have been developed. Typically the assembled batteries have capacities from 0.1 to 5 mAh. The operation of a thin film battery is depicted in the schematic diagram (Fig. 2). Very simply, when the battery is allowed to discharge, a Li + ion migrates from the anode to the cathode film by diffusing through the solid electrolyte. When the anode and cathode reactions are reversible, as for an intercalation compound or alloy, the battery can be recharged by reversing the current. The difference in the electrochemical potential of the lithium determines the cell voltage. Most of the thin films used in current commercial variations of this thin film battery are deposited in vacuum chambers by RF and DC magnetron sputtering and by thermal evaporation onto unheated substrates. In addition, many publications report exploring a variety of other physical and chemical vapor deposition processes, such as pulsed laser deposition, electron cyclotron resonance sputtering, and

  11. Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111 substrates by intermittent microwave assisted hydrothermal method

    Directory of Open Access Journals (Sweden)

    Ivan Velasco-Davalos

    2016-06-01

    Full Text Available We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111 substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO34− or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111 and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111 substrates. Bi(NO33 and Fe(NO33 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100 substrates was verified by piezoresponse force microscopy.

  12. Effect of (Cd:ZnS Particle Concentration and Photoexcitation on the Electrical and Ferroelectric Properties of (Cd:ZnS/P(VDF-TrFE Composite Films

    Directory of Open Access Journals (Sweden)

    Sebastian Engel

    2017-11-01

    Full Text Available The influence of semiconductor particle concentration and photoexcitation on the electrical and ferroelectric properties of ferroelectric-semiconductor-composites was investigated. For this purpose, 32 µm thin films of poly(vinylidene fluoride-co-trifluoroethylene with (Cd:ZnS particle concentrations of between 0 and 20 vol % were fabricated and characterized by scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, and optical spectroscopy. It was shown that the particle concentration has only a negligible influence on the molecular structure of the polymer but strongly determines the optical properties of the composite. For (Cd:ZnS particle concentrations below 20 vol %, the I-V characteristics of the composites is only marginally affected by the particle concentration and the optical excitation of the composite material. On the contrary, a strong influence of both parameters on the ferro- and pyroelectric properties of the composite films was observed. For particle fractions that exhibit ferroelectric hysteresis, an increased remanent polarization and pyroelectric coefficient due to optical excitation was obtained. A theoretical approach that is based on a “three phase model” of the internal structure was developed to explain the observed results.

  13. Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

    Energy Technology Data Exchange (ETDEWEB)

    Kurogi, H; Yamagata, Y; Ebihara, K [Kumamoto Univ. (Japan). Dept. of Electr. Eng. and Comput. Sci.; Inoue, N [Kyushu Electric Power Co., Inc., Suizenji, 1-6-36, Kumamoto 862 (Japan)

    1998-03-01

    Pb(Zr{sub X}Ti{sub 1-X})O{sub 3} (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, {lambda}=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm{sup -2} on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P{sub r}=15 {mu}C cm{sup -2}, 30 {mu}C cm{sup -2} and E{sub c}=200 kV cm{sup -1}, 100 kV cm{sup -1} for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10{sup 8} cycles of switching. (orig.) 7 refs.

  14. Temporary formation of highly conducting domain walls for non-destructive read-out of ferroelectric domain-wall resistance switching memories

    Science.gov (United States)

    Jiang, Jun; Bai, Zi Long; Chen, Zhi Hui; He, Long; Zhang, David Wei; Zhang, Qing Hua; Shi, Jin An; Park, Min Hyuk; Scott, James F.; Hwang, Cheol Seong; Jiang, An Quan

    2018-01-01

    Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO3 thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

  15. Ultra Uniform Pb0.865La0.09(Zr0.65Ti0.35O3 Thin Films with Tunable Optical Properties Fabricated via Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    Shenglin Jiang

    2018-03-01

    Full Text Available Ferroelectric thin films have been utilized in a wide range of electronic and optical applications, in which their morphologies and properties can be inherently tuned by a qualitative control during growth. In this work, we demonstrate the evolution of the Pb0.865La0.09(Zr0.65Ti0.35O3 (PLZT thin films on MgO (200 with high uniformity and optimized optical property via the controls of the deposition temperatures and oxygen pressures. The perovskite phase can only be obtained at the deposition temperature above 700 °C and oxygen pressure over 50 Pa due to the improved crystallinity. Meanwhile, the surface morphologies gradually become smooth and compact owing to spontaneously increased nucleation sites with the elevated temperatures, and the crystallization of PLZT thin films also sensitively respond to the oxygen vacancies with the variation of oxygen pressures. Correspondingly, the refractive indices gradually develop with variations of the deposition temperatures and oxygen pressures resulted from the various slight loss, and the extinction coefficient for each sample is similarly near to zero due to the relatively smooth morphology. The resulting PLZT thin films exhibit the ferroelectricity, and the dielectric constant sensitively varies as a function of electric filed, which can be potentially applied in the electronic and optical applications.

  16. Tunability, dielectric, and piezoelectric properties of Ba{sub (1−x)}Ca{sub x}Ti{sub (1−y)}Zr{sub y}O{sub 3} ferroelectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Daumont, C. J. M., E-mail: christophe.daumont@univ-tours.fr; Le Mouellic, E.; Negulescu, B.; Wolfman, J. [Laboratoire GREMAN, UMR7347 CNRS, Faculté de Sciences et Techniques, Université François Rabelais, 37200 Tours (France); Simon, Q.; Payan, S.; Maglione, M. [Institute of Condensed Matter Chemistry of Bordeaux, ICMCB-CNRS, Université de Bordeaux, 33608 Pessac Cedex (France); Gardes, P.; Poveda, P. [STMicroelectronics, 10 rue Thalès de Milet, 37071 Tours Cedex (France)

    2016-03-07

    Tunable ferroelectric capacitors, which exhibit a decrease of the dielectric permittivity (ϵ) under electric field, are widely used in electronics for RF tunable applications (e.g., antenna impedance matching). Current devices use barium strontium titanate as the tunable dielectric, and the need for performance enhancement of the tunable element is the key for device improvement. We report here on libraries of Ba{sub 0.97}Ca{sub 0.03}Ti{sub 1−x}Zr{sub x}O{sub 3} thin films (0 ≤ x ≤ 27%) with a thickness of about 130 nm deposited on IrO{sub 2}/SiO{sub 2}/Si substrates using combinatorial pulsed laser deposition allowing for gradients of composition on one sample. A total of 600 capacitors on a single sample were characterized in order to statistically investigate the dielectric properties. We show that the tunabilty is maximum at intermediate compositions, reaching values up to 60% for an electric field of about 400 kV cm{sup −1}. We attribute the high tunability in the intermediate compositions to the paraelectric-ferroelectric phase transition, which is brought down to room temperature by the addition of Zr. In addition, the piezoelectric coefficient is found to be decreasing with increasing Zr content.

  17. Electric double layer transistors with ferroelectric BaTiO3 channels

    NARCIS (Netherlands)

    Ito, M.; Matsubara, Y.; Kozuka, Y.; Takahashi, K. S.; Kagawa, F.; Ye, J. T.; Iwasa, Y.; Ueno, K.; Tokura, Y.; Kawasaki, M.

    2014-01-01

    We report the surface conduction of a BaTiO3 thin film using electric double layer transistor (EDLT) structure. A transistor operation was observed at 220 K with an on/off ratio exceeding 10(5), demonstrating that ionic liquid gating is effective to induce carriers at the surface of ferroelectric

  18. Effect of incorporating nonlanthanoidal indium on the ferroelectric performance of Bi4Ti3O12 thin films

    Science.gov (United States)

    Chang, Y. C.; Kuo, D. H.

    2006-08-01

    Nonlanthanoid-substituted In-x-Bi4Ti3O12 films with different indium contents at x =0, 0.2, 0.4, and 0.5, based upon the chemical formula of (Bi4-xInx)Ti3O12, were prepared at 600°C by chemical solution deposition. In-0.4-Bi4Ti3O12 films displayed a large remanent polarization of 57μC /cm2, coercive field of 100KV/cm, high nonvolatile polarization ⩾30μC/cm2 after 1010 switching cycles, and low annealing temperature of 600°C. Good ferroelectric properties are mainly attributed to the partial substitution of the smaller-sized Ti4+ site by the larger-sized In3+ to enhance electrical polarization by a dimensional change of unit cell and to provide fatigue resistance by lattice distortion and chemical stabilization.

  19. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  20. Retention Characteristics of CBTi144 Thin Films Explained by Means of X-Ray Photoemission Spectroscopy

    Directory of Open Access Journals (Sweden)

    G. Biasotto

    2010-01-01

    Full Text Available CaBi4Ti4O15 (CBTi144 thin films were grown on Pt/Ti/SiO2/Si substrates using a soft chemical solution and spin-coating method. Structure and morphology of the films were characterized by the X-ray Diffraction (XRD, Fourier-transform infrared spectroscopy (FT-IR, Raman analysis, X-ray photoemission spectroscopy (XPS, and transmission electron microscopy (TEM. The films present a single phase of layered-structured perovskite with polar axis orient. The a/b-axis orientation of the ferroelectric film is considered to be associated with the preferred orientation of the Pt bottom electrode. XPS measurements were employed to understand the nature of defects on the retention behavior of CBTi144 films. We have observed that the main source of retention-free characteristic of the capacitors is the oxygen environment in the CBTi144 lattice.

  1. Hardware Modifications to the US Army Research Laboratory’s Metalorganic Chemical Vapor Deposition (MOCVD) System for Optimization of Complex Oxide Thin Film Fabrication

    Science.gov (United States)

    2015-04-01

    the total absorbance, or the fraction of radiation absorbed at the measured wavelength; is the calculated molar extinction coefficient for the...of PZT thin films by liquid delivery MOCVD. Integrated Ferroelectrics. 2002;46:125–131. 14. Hiskes R, Dicarolis SA, Jacowitz RD, Lu Z, Feigelson RS

  2. Leakage current behavior in lead-free ferroelectric (K,Na)NbO3-LiTaO3-LiSbO3 thin films

    Science.gov (United States)

    Abazari, M.; Safari, A.

    2010-12-01

    Conduction mechanisms in epitaxial (001)-oriented pure and 1 mol % Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrate were investigated. Temperature dependence of leakage current density was measured as a function of applied electric field in the range of 200-380 K. It was shown that the different transport mechanisms dominate in pure and Mn-doped thin films. In pure (KNN-LT-LS) thin films, Poole-Frenkel emission was found to be responsible for the leakage, while Schottky emission was the dominant mechanism in Mn-doped thin films at higher electric fields. This is a remarkable yet clear indication of effect of 1 mol % Mn on the resistive behavior of such thin films.

  3. Electro-acoustic sensors based on AlN thin film: possibilities and limitations

    Science.gov (United States)

    Wingqvist, Gunilla

    2011-06-01

    The non-ferroelectric polar wurtzite aluminium nitride (AlN) material has been shown to have potential for various sensor applications both utilizing the piezoelectric effect directly for pressure sensors or indirectly for acoustic sensing of various physical, chemical and biochemical sensor applications. Especially, sputter deposited AlN thin films have played a central role for successful development of the thin film electro-acoustic technology. The development has been primarily driven by one device - the thin film bulk acoustic resonator (FBAR or TFBAR), with its primary use for high frequency filter applications for the telecom industry. AlN has been the dominating choice for commercial application due to compatibility with the integrated circuit technology, low acoustic and dielectric losses, high acoustic velocity in combination with comparably high (but still for some applications limited) electromechanical coupling. Recently, increased piezoelectric properties (and also electromechanical coupling) in the AlN through the alloying with scandium nitride (ScN) have been identified both experimentally and theoretically. Inhere, the utilization of piezoelectricity in electro-acoustic sensing will be discussed together with expectation on acoustic FBAR sensor performance with variation in piezoelectric material properties in the parameter space around AlN due to alloying, in view of the ScxAl1-xN (0

  4. A hybrid ferroelectric-flash memory cells

    Science.gov (United States)

    Park, Jae Hyo; Byun, Chang Woo; Seok, Ki Hwan; Kim, Hyung Yoon; Chae, Hee Jae; Lee, Sol Kyu; Son, Se Wan; Ahn, Donghwan; Joo, Seung Ki

    2014-09-01

    A ferroelectric-flash (F-flash) memory cells having a metal-ferroelectric-nitride-oxynitride-silicon structure are demonstrated, and the ferroelectric materials were perovskite-dominated Pb(Zr,Ti)O3 (PZT) crystallized by Pt gate electrode. The PZT thin-film as a blocking layer improves electrical and memorial performance where programming and erasing mechanism are different from the metal-ferroelectric-insulator-semiconductor device or the conventional silicon-oxide-nitride-oxide-silicon device. F-flash cells exhibit not only the excellent electrical transistor performance, having 442.7 cm2 V-1 s-1 of field-effect mobility, 190 mV dec-1 of substhreshold slope, and 8 × 105 on/off drain current ratio, but also a high reliable memory characteristics, having a large memory window (6.5 V), low-operating voltage (0 to -5 V), faster P/E switching speed (50/500 μs), long retention time (>10 years), and excellent fatigue P/E cycle (>105) due to the boosting effect, amplification effect, and energy band distortion of nitride from the large polarization. All these characteristics correspond to the best performances among conventional flash cells reported so far.

  5. Theoretical study of ferroelectric nanoparticles using phase reconstructed electron microscopy

    Science.gov (United States)

    Phatak, C.; Petford-Long, A. K.; Beleggia, M.; De Graef, M.

    2014-06-01

    Ferroelectric nanostructures are important for a variety of applications in electronic and electro-optical devices, including nonvolatile memories and thin-film capacitors. These applications involve stability and switching of polarization using external stimuli, such as electric fields. We present a theoretical model describing how the shape of a nanoparticle affects its polarization in the absence of screening charges, and quantify the electron-optical phase shift for detecting ferroelectric signals with phase-sensitive techniques in a transmission electron microscope. We provide an example phase shift computation for a uniformly polarized prolate ellipsoid with varying aspect ratio in the absence of screening charges.

  6. Host thin films incorporating nanoparticles

    Science.gov (United States)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  7. Investigation of ferroelectric materials by the thermal noise method: advantages and limitations

    Czech Academy of Sciences Publication Activity Database

    Bednyakov, Petr; Shnaidshtein, I. V.; Strukov, B. A.

    2016-01-01

    Roč. 500, č. 1 (2016), 203-217 ISSN 0015-0193 R&D Projects: GA ČR GA13-15110S Institutional support: RVO:68378271 Keywords : thermal noise * ferroelectricity * thin films * dielectric permittivity * equivalent circuit Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.551, year: 2016

  8. Microwave properties of film Ba x Sr1 - x TiO3 ferroelectric variconds with a magnesium-containing additive

    Science.gov (United States)

    Tumarkin, A. V.; Tepina, E. R.; Nenasheva, E. A.; Kartenko, N. F.; Kozyrev, A. B.

    2012-06-01

    The electrophysical properties of bulk ceramics based on Ba x Sr1 - x TiO3 solid solutions with a Mg-containing additive and planar variconds based on ferroelectric films obtained by the ion-plasma sputtering of targets with different elemental compositions are studied. Controllability n( U) = C(0)/ C( U) and the dielectric loss tangent (tanδ) of ferroelectric variconds are measured as functions of the elemental composition of the ferroelectric. The figure of merit of the variconds is estimated, and the film composition providing the best electrophysical parameters is determined.

  9. Nonvolatile ferroelectric memory based on PbTiO3 gated single-layer MoS2 field-effect transistor

    Science.gov (United States)

    Shin, Hyun Wook; Son, Jong Yeog

    2018-01-01

    We fabricated ferroelectric non-volatile random access memory (FeRAM) based on a field effect transistor (FET) consisting of a monolayer MoS2 channel and a ferroelectric PbTiO3 (PTO) thin film of gate insulator. An epitaxial PTO thin film was deposited on a Nb-doped SrTiO3 (Nb:STO) substrate via pulsed laser deposition. A monolayer MoS2 sheet was exfoliated from a bulk crystal and transferred to the surface of the PTO/Nb:STO. Structural and surface properties of the PTO thin film were characterized by X-ray diffraction and atomic force microscopy, respectively. Raman spectroscopy analysis was performed to identify the single-layer MoS2 sheet on the PTO/Nb:STO. We obtained mobility value (327 cm2/V·s) of the MoS2 channel at room temperature. The MoS2-PTO FeRAM FET showed a wide memory window with 17 kΩ of resistance variation which was attributed to high remnant polarization of the epitaxially grown PTO thin film. According to the fatigue resistance test for the FeRAM FET, however, the resistance states gradually varied during the switching cycles of 109. [Figure not available: see fulltext.

  10. NMR characterization of thin films

    Science.gov (United States)

    Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2010-06-15

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  11. NMR characterization of thin films

    Science.gov (United States)

    Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2008-11-25

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  12. Handbook of thin film technology

    CERN Document Server

    Frey, Hartmut

    2015-01-01

    “Handbook of Thin Film Technology” covers all aspects of coatings preparation, characterization and applications. Different deposition techniques based on vacuum and plasma processes are presented. Methods of surface and thin film analysis including coating thickness, structural, optical, electrical, mechanical and magnetic properties of films are detailed described. The several applications of thin coatings and a special chapter focusing on nanoparticle-based films can be found in this handbook. A complete reference for students and professionals interested in the science and technology of thin films.

  13. Nondestructive investigatons of the depth profile of PZT ferroelectric films

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Glinchuk, M. D.; Jastrabík, Lubomír; Suchaneck, G.; Gerlach, G.

    2001-01-01

    Roč. 264, - (2001), s. 151-156 ISSN 0015-0193 R&D Projects: GA MŠk LN00A015; GA ČR GA202/00/1425 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferroelectric film * depth profile * interface Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.471, year: 2001

  14. Dependency of the properties of Sr xBi yTa2O9 thin films on the Sr and Bi stoichiometry

    International Nuclear Information System (INIS)

    Viapiana, Matteo; Schwitters, Michael; Wouters, Dirk J.; Maes, Herman E.; Van der Biest, Omer

    2005-01-01

    In this study the properties of ferroelectric SBT thin films crystallized at 700 deg. C have been investigated as function of the Sr and Bi stoichiometry. A matrix of 130 nm Sr x Bi y Ta 2 O 9 films with 0.7 ≤ x ≤ 1.0 and 2.0 ≤ y ≤ 2.4 has been realized by metal-organic spin-on deposition technique on Pt/IrO 2 /Ir/TiAlN/SiO 2 /Si substrates. Within this composition range, we found that the ferroelectric properties peak into a narrow window of 0.8 ≤ x ≤ 0.9 and y ∼ 2.25 with Pr and Ec of 6.5 μC/cm 2 and 50 kV/cm, respectively (at 2.5 V). Outside this composition window, the Pr decreases while the hysteresis loop becomes slanted. For some Sr/Bi-ratios even no ferroelectricity was achieved. 2Ec-tendencies were seen as function of the x/y-ratios, too. Examination of the microstructure of the films by scanning electron microscopy showed that film grain size increased with decreasing Sr-deficiency and that nucleation increased with increasing Bi-excess. At high Sr-deficiency and low Bi-excess, no complete crystallization of the SBT film occurs. From the film morphology, also different phases can be discriminated. X-ray diffraction analysis showed a strong correlation of the film orientation with the film composition. While our results show a clear correlation of Pr, film grain size and orientation with composition, further investigations are required to clarify the relation of the hysteresis parameters with film orientation

  15. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  16. Thin-film solar cells

    International Nuclear Information System (INIS)

    Aberle, Armin G.

    2009-01-01

    The rapid progress that is being made with inorganic thin-film photovoltaic (PV) technologies, both in the laboratory and in industry, is reviewed. While amorphous silicon based PV modules have been around for more than 20 years, recent industrial developments include the first polycrystalline silicon thin-film solar cells on glass and the first tandem solar cells based on stacks of amorphous and microcrystalline silicon films ('micromorph cells'). Significant thin-film PV production levels are also being set up for cadmium telluride and copper indium diselenide.

  17. Deposition of PZT Thin Films on Polymer Substrate by Means of Low Pressure Plasma Jet Systém

    Czech Academy of Sciences Publication Activity Database

    Deyneka, Alexander; Hubička, Zdeněk; Jastrabík, Lubomír; Čada, Martin; Virostko, Petr; Olejníček, Jiří; Suchaneck, G.; Gerlach, G.

    2005-01-01

    Roč. 316, - (2005), s. 157-166 ISSN 0015-0193 R&D Projects: GA AV ČR(CZ) KJB1010301; GA ČR(CZ) GP202/02/D078; GA AV ČR(CZ) KJB1010302 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : ferroelectric thin films * spectral ellipsometry * hollow cathode sputtering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.459, year: 2005

  18. Process for forming thin film, heat treatment process of thin film sheet, and heat treatment apparatus therefor

    International Nuclear Information System (INIS)

    Watanabe, S.

    1984-01-01

    The invention provides a process for forming a magnetic thin film on a base film, a heat treatment process of a thin film sheet consisting of the base film and the magnetic thin film, and an apparatus for performing heat treatment of the thin film sheet. Tension applied to the thin film sheet is substantially equal to that applied to the base film when the magnetic thin film is formed thereon. Then, the thin film sheet is treated with heat. The thin film sheet is heated with a given temperature gradient to a reactive temperature at which heat shrinkage occurs, while the tension is being applied thereto. Thereafter, the thin film sheet to which the tension is still applied is cooled with substantially the same temperature gradient as applied in heating. The heat treatment apparatus has a film driving unit including a supply reel, a take-up reel, a drive source and guide rollers; a heating unit including heating plates, heater blocks and a temperature controller for heating the sheet to the reactive temperature; and a heat insulating unit including a thermostat and another temperature controller for maintaining the sheet at the nonreactive temperature which is slightly lower than the reactive temperature

  19. Absence of low temperature phase transitions and enhancement of ferroelectric transition temperature in highly strained BaTiO{sub 3} epitaxial films grown on MgO Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Satish; Kumar, Dhirendra; Sathe, V. G., E-mail: vasant@csr.res.in [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India); Kumar, Ravi; Sharma, T. K. [Semiconductor Physics and Devices Lab, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2015-04-07

    Recently, a large enhancement in the ferroelectric transition temperature of several oxides is reported by growing the respective thin films on appropriate substrates. This phenomenon is correlated with high residual strain in thin films often leading to large increase in the tetragonality of their crystal structure. However, such an enhancement of transition temperature is usually limited to very thin films of ∼10 nm thickness. Here, we report growth of fully strained epitaxial thin films of BaTiO{sub 3} of 400 nm thickness, which are coherently grown on MgO substrates by pulsed laser deposition technique. Conventional high resolution x-ray diffraction and also the reciprocal space map measurements confirm that the film is fully strained with in-plane tensile strain of 5.5% that dramatically increases the tetragonality to 1.05. Raman measurements reveal that the tetragonal to cubic structural phase transition is observed at 583 K, which results in an enhancement of ∼200 K. Furthermore, temperature dependent Raman studies on these films corroborate absence of all the low temperature phase transitions. Numerical calculations based on thermodynamical model predict a value of the transition temperature that is greater than 1500 °C. Our experimental results are therefore in clear deviation from the existing strain dependent phase diagrams.

  20. Effect of elastic compliances and higher order Landau coefficients on the phase diagram of single domain epitaxial Pb(Zr,TiO3 (PZT thin films

    Directory of Open Access Journals (Sweden)

    M. Mtebwa

    2014-12-01

    Full Text Available We report the qualitative study of the influence of both elastic compliances and higher order terms of Landau free energy potential on the phase diagram of Pb(Zr0.5Ti0.5O3 thin films by using a single domain Landau theory. Although the impact of elastic compliances and higher order terms of the Landau free energy potential on the phase diagram of ferroelectric thin films are known, the sensitivity of the phase diagram of PZT thin film on these parameters have not been reported. It is demonstrated that, while values of elastic compliances affect the positions of the phase boundaries including phase transition temperature of the cubic phase; higher order terms can potentially introduce an a1a2-phase previously predicted in PbTiO3 phase diagram.

  1. Electrical properties of SrBi2Ta2O9 thin films deposited on Si (100) substrates by rf magnetron sputtering

    International Nuclear Information System (INIS)

    Roy, A.; Jha, G.; Dhar, A.; Ray, S.K.; Manna, I.

    2008-01-01

    Recently, metal-ferroelectric-semiconductor (MFS) structures have attracted much attention because of its potentials as nonvolatile memory device with nondestructive readout operation. In the present study ferroelectric SrBi 2 Ta 2 O 9 (SBT) thin films are grown on p-type (100) Si substrates by rf magnetron sputtering method at different deposition conditions. The crystallinity of the films is studied using grazing incidence X-ray diffraction (GIXRD) pattern. The spectra show the film are polycrystalline with dominant orientation along (115) plane. The capacitance-voltage (C-V) characteristics of Al/SBT/Si capacitors were measured at 100 kHz. The (C-V) characteristic of AI/SBT/Si capacitor post-annealed at 700-800 deg C shows a hysteresis nature with a clockwise rotation and the memory window of the hysteresis loop is 0.88 V when the gate voltage is ± 5 V. The interface trap density (D it ) calculated by using Hills method at room temperature and a value in the order of 10 11 -10 12 eV -1 cm -2 was found at mid gap region depending on the crystallization temperature. The surface morphology was investigated by atomic force microscope (AFM). The study showed the potential of SBT for application in metal- ferroelectric-silicon nonvolatile memory devices. (author)

  2. Self-assembled single-phase perovskite nanocomposite thin films.

    Science.gov (United States)

    Kim, Hyun-Suk; Bi, Lei; Paik, Hanjong; Yang, Dae-Jin; Park, Yun Chang; Dionne, Gerald F; Ross, Caroline A

    2010-02-10

    Thin films of perovskite-structured oxides with general formula ABO(3) have great potential in electronic devices because of their unique properties, which include the high dielectric constant of titanates, (1) high-T(C) superconductivity in cuprates, (2) and colossal magnetoresistance in manganites. (3) These properties are intimately dependent on, and can therefore be tailored by, the microstructure, orientation, and strain state of the film. Here, we demonstrate the growth of cubic Sr(Ti,Fe)O(3) (STF) films with an unusual self-assembled nanocomposite microstructure consisting of (100) and (110)-oriented crystals, both of which grow epitaxially with respect to the Si substrate and which are therefore homoepitaxial with each other. These structures differ from previously reported self-assembled oxide nanocomposites, which consist either of two different materials (4-7) or of single-phase distorted-cubic materials that exhibit two or more variants. (8-12) Moreover, an epitaxial nanocomposite SrTiO(3) overlayer can be grown on the STF, extending the range of compositions over which this microstructure can be formed. This offers the potential for the implementation of self-organized optical/ferromagnetic or ferromagnetic/ferroelectric hybrid nanostructures integrated on technologically important Si substrates with applications in magnetooptical or spintronic devices.

  3. Phase transitions and optical characterization of lead-free piezoelectric (K0.5Na0.5)0.96Li0.04(Nb 0.8Ta0.2)O3 thin films

    KAUST Repository

    Yao, Yingbang

    2013-06-01

    Lead-free piezoelectric thin films, (K0.5Na0.5) 0.96Li0.04(Nb0.8Ta0.2)O 3, were epitaxially grown on MgO(001) and Nb-doped SrTiO 3(001) substrates using pulsed laser deposition. The optimum deposition temperature was found to be 600 C. Two types of in-plane orientations were observed in the films depending on the substrates used. The transmittance and photoluminescence spectra as well as the dielectric and ferroelectric properties of the films were measured. The measured band-gap energy was found to be decreased with the deposition temperature. The dielectric constant decreased from 550 to 300 as the frequency increased from 100 Hz to 1 MHz. The measured remnant polarization and coercive field were 4 μC/cm2 and 68 kV/cm, respectively. The phase transitions of the films were studied by Raman spectroscopy. Two distinct anomalies originating from the cubic-to-tetragonal (TC-T ~ 300 C) and tetragonal-to-orthorhombic (TT-O ~ 120 C) phase transitions were observed. Our results show that Raman spectroscopy is a powerful tool in identifying the phase transitions in ferroelectric thin films. © 2013 Elsevier B.V.

  4. Enhanced piezoelectric properties of (110)-oriented PbZr1−xTixO3 epitaxial thin films on silicon substrates at shifted morphotropic phase boundary

    NARCIS (Netherlands)

    Wan, X.; Houwman, Evert Pieter; Steenwelle, Ruud Johannes Antonius; van Schaijk, R.; Nguyen, Duc Minh; Dekkers, Jan M.; Rijnders, Augustinus J.H.M.

    2014-01-01

    Piezoelectrical, ferroelectrical, and structural properties of epitaxial pseudocubic (110)pc oriented 500 nm thick PbZr1−xTixO3 thin films, prepared by pulsed laser deposition on (001) silicon substrates, were measured as a function of composition. The dependence of the measurement data on the Ti

  5. High-performance ferroelectric memory based on phase-separated films of polymer blends

    KAUST Repository

    Khan, Yasser; Bhansali, Unnat Sampatraj; Almadhoun, Mahmoud N.; Odeh, Ihab N.; Cha, Dong Kyu; Alshareef, Husam N.

    2013-01-01

    High-performance polymer memory is fabricated using blends of ferroelectric poly(vinylidene-fluoride-trifluoroethylene) (P(VDF-TrFE)) and highly insulating poly(p-phenylene oxide) (PPO). The blend films spontaneously phase separate into amorphous PPO nanospheres embedded in a semicrystalline P(VDF-TrFE) matrix. Using low molecular weight PPO with high miscibility in a common solvent, i.e., methyl ethyl ketone, blend films are spin cast with extremely low roughness (Rrms ≈ 4.92 nm) and achieve nanoscale phase seperation (PPO domain size < 200 nm). These blend devices display highly improved ferroelectric and dielectric performance with low dielectric losses (<0.2 up to 1 MHz), enhanced thermal stability (up to ≈353 K), excellent fatigue endurance (80% retention after 106 cycles at 1 KHz) and high dielectric breakdown fields (≈360 MV/m). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. High-performance ferroelectric memory based on phase-separated films of polymer blends

    KAUST Repository

    Khan, Yasser

    2013-10-29

    High-performance polymer memory is fabricated using blends of ferroelectric poly(vinylidene-fluoride-trifluoroethylene) (P(VDF-TrFE)) and highly insulating poly(p-phenylene oxide) (PPO). The blend films spontaneously phase separate into amorphous PPO nanospheres embedded in a semicrystalline P(VDF-TrFE) matrix. Using low molecular weight PPO with high miscibility in a common solvent, i.e., methyl ethyl ketone, blend films are spin cast with extremely low roughness (Rrms ≈ 4.92 nm) and achieve nanoscale phase seperation (PPO domain size < 200 nm). These blend devices display highly improved ferroelectric and dielectric performance with low dielectric losses (<0.2 up to 1 MHz), enhanced thermal stability (up to ≈353 K), excellent fatigue endurance (80% retention after 106 cycles at 1 KHz) and high dielectric breakdown fields (≈360 MV/m). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. DC magnetron sputtering prepared Ag-C thin film anode for thin film lithium ion microbatteries

    International Nuclear Information System (INIS)

    Li, Y.; Tu, J.P.; Shi, D.Q.; Huang, X.H.; Wu, H.M.; Yuan, Y.F.; Zhao, X.B.

    2007-01-01

    An Ag-C thin film was prepared by DC magnetron co-sputtering, using pure silver and graphite as the targets. The microstructure and morphology of the deposited thin film were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Electrochemical performances of the Ag-C thin film anode were investigated by means of discharge/charge and cyclic voltammogram (CV) tests in model cells. The electrochemical impedance spectrum (EIS) characteristics and the chemical diffusion coefficient, D Li of the Ag-C thin film electrode at different discharging states were discussed. It was believed that the excellent cycling performance of the Ag-C electrode was ascribed to the good conductivity of silver and the volume stability of the thin film

  8. Crystallographic orientations and electrical properties of Bi sub 3 sub . sub 4 sub 7 La sub 0. sub 8 sub 5 Ti sub 3 O sub 1 sub 2 thin films on Pt/Ti/SiO sub 2 /Si and Pt/SiO sub 2 /Si substrates

    CERN Document Server

    Ryu, S O; Lee, W J

    2003-01-01

    We report on the crystallization and electrical properties of Bi sub 3 sub . sub 4 sub 7 La sub 0 sub . sub 8 sub 5 Ti sub 3 O sub 1 sub 2 (BLT) thin films for possible ferroelectric non-volatile memory applications. The film properties were found to be strongly dependent on process conditions especially on the intermediate heat treatment conditions. The crystallographic orientation of the films showed sharp changes at the intermediate rapid thermal annealing (RTA) temperature of 450degC. Below 450degC, BLT thin films have (117) orientation while they have preffered c-axis orientation above 450degC. We found that RTA conditions of the first coating layer play a major role in determining the entire crystallographic orientation of the films. The films also showed of ferroelectric hysterisis behavior strongly dependent on RTA treatment. In fact, the remanent polarization of Bi sub 3 sub . sub 4 sub 6 sub 5 La sub 0 sub . sub 8 sub 5 Ti sub 3 O sub 1 sub 2 thin films having (001) preferred crystallographic orient...

  9. Boosting the Recoverable Energy Density of Lead-Free Ferroelectric Ceramic Thick Films through Artificially Induced Quasi-Relaxor Behavior.

    Science.gov (United States)

    Peddigari, Mahesh; Palneedi, Haribabu; Hwang, Geon-Tae; Lim, Kyung Won; Kim, Ga-Yeon; Jeong, Dae-Yong; Ryu, Jungho

    2018-06-08

    Dielectric ceramic film capacitors, which store energy in the form of electric polarization, are promising for miniature pulsed power electronic device applications. For a superior energy storage performance of the capacitors, large recoverable energy density, along with high efficiency, high power density, fast charge/discharge rate, and good thermal/fatigue stability, is desired. Herein, we present highly dense lead-free 0.942[Na 0.535 K 0.480 NbO 3 ]-0.058LiNbO 3 (KNNLN) ferroelectric ceramic thick films (∼5 μm) demonstrating remarkable energy storage performance. The nanocrystalline KNNLN thick film fabricated by aerosol deposition (AD) process and annealed at 600 °C displayed a quasi-relaxor ferroelectric behavior, which is in contrast to the typical ferroelectric nature of the KNNLN ceramic in its bulk form. The AD film exhibited a large recoverable energy density of 23.4 J/cm 3 , with an efficiency of over 70% under the electric field of 1400 kV/cm. Besides, an ultrahigh power density of 38.8 MW/cm 3 together with a fast discharge speed of 0.45 μs, good fatigue endurance (up to 10 6 cycles), and thermal stability in a wide temperature range of 20-160 °C was also observed. Using the AD process, we could make a highly dense microstructure of the film containing nano-sized grains, which gave rise to the quasi-relaxor ferroelectric characteristics and the remarkable energy storage properties.

  10. Sol-gel preparation of lead magnesium niobate (PMN) powders and thin films

    Science.gov (United States)

    Boyle, T.J.

    1999-01-12

    A method of preparing a lead magnesium niobium oxide (PMN), Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}, precursor solution by a solvent method wherein a liquid solution of a lead-complex PMN precursor is combined with a liquid solution of a niobium-complex PMN precursor, the combined lead- and niobium-complex liquid solutions are reacted with a magnesium-alkyl solution, forming a PMN precursor solution and a lead-based precipitate, and the precipitate is separated from the reacted liquid PMN precursor solution to form a precipitate-free PMN precursor solution. This precursor solution can be processed to form both ferroelectric powders and thin films. 3 figs.

  11. Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Rama K [ORNL; Bogle, K A [University of New South Wales, Sydney, Australia; Kumar, Amit [ORNL; Jesse, Stephen [ORNL; Magaraggia, R [University of Glasgow; Stamps, R [University of Glasgow; Ogale, S [National Chemical Laboratory, India; Potdar, H S [National Chemical Laboratory, India

    2011-01-01

    Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of 1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO.

  12. Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level

    Science.gov (United States)

    Vasudevan, R. K.; Bogle, K. A.; Kumar, A.; Jesse, S.; Magaraggia, R.; Stamps, R.; Ogale, S. B.; Potdar, H. S.; Nagarajan, V.

    2011-12-01

    Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1-xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of ˜1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO.

  13. Polarization-tuned diode behaviour in multiferroic BiFeO3 thin films

    KAUST Repository

    Yao, Yingbang

    2012-12-28

    Asymmetric rectifying I-V behaviour of multiferroic BiFeO3 (BFO) thin films grown on transparent ITO-coated glass was quantitatively studied as a function of ferroelectric polarization. Different polarized states were established by unipolar or bipolar poling with various applied electric fields. The effects of polarization relaxation and fatigue on the currents were also investigated. We found that the conduction currents and the associated rectifications were controlled by the amplitude and direction of the polarization. We clearly observed the linear dependence of the current on the polarization. It is suggested that the space-charge-limited conduction and the charge injection at the Schottky interface between the film and the electrodes dominate the current. The electrically controlled rectifying behaviour observed in this study may be useful in nonvolatile resistance memory devices or tunable diodes. © 2013 IOP Publishing Ltd.

  14. Epitaxial Pb(Zr,Ti)O3 thin films for a MEMS application

    International Nuclear Information System (INIS)

    Nguyen, Minh D; Vu, Hung N; Blank, Dave H A; Rijnders, Guus

    2011-01-01

    This research presents the deposition and device fabrication of epitaxial Pb(Zr,Ti)O 3 (PZT) thin films for applications in microelectromechanical systems (MEMS). A piezoelectric micro-membrane is described as an example. Using the pulsed laser deposition (PLD) technique and the MEMS microfabrication process, the piezo-membranes with diameters ranging from 200 to 500 μm were obtained. The displacement of piezo-membranes increased from 5.1 to 17.5 nm V −1 with a piezoelectric-membrane diameter in the range of 200–500 μm. Furthermore, the effect of PZT film-thickness on the mechanical properties has been investigated. By using the conductive-oxide SrRuO 3 (SRO) layers as the electrodes, the degradation of both ferroelectric and piezoelectric properties is prevented up to 10 10 switching cycles

  15. Epitaxial Oxide Thin Films Grown by Solid Source Metal-Organic Chemical Vapor Deposition.

    Science.gov (United States)

    Lu, Zihong

    1995-01-01

    The conventional liquid source metal-organic chemical vapor deposition (MOCVD) technique is capable of producing large area, high quality, single crystal semiconductor films. However, the growth of complex oxide films by this method has been hampered by a lack of suitable source materials. While chemists have been actively searching for new source materials, the research work reported here has demonstrated the successful application of solid metal-organic sources (based on tetramethylheptanedionate) to the growth of high quality thin films of binary compound cerium dioxide (CeO_2), and two more complex materials, the ternary compound lithium niobate (LiNbO_3), with two cations, and the quaternary compound strontium barium niobate (SBN), with three cations. The growth of CeO_2 thin films on (1012)Al_2O_3 substrates has been used as a model to study the general growth behavior of oxides. Factors affecting deposition rate, surface morphology, out-of-plane mosaic structure, and film orientation have been carefully investigated. A kinetic model based on gas phase prereaction is proposed to account for the substrate temperature dependence of film orientation found in this system. Atomically smooth, single crystal quality cerium dioxide thin films have been obtained. Superconducting YBCO films sputtered on top of solid source MOCVD grown thin cerium dioxide buffer layers on sapphire have been shown to have physical properties as good as those of YBCO films grown on single crystal MgO substrates. The thin film growth of LiNbO_3 and Sr_{1-x}Ba _{x}Nb_2 O_6 (SBN) was more complex and challenging. Phase purity, transparency, in-plane orientation, and the ferroelectric polarity of LiNbO _3 films grown on sapphire substrates was investigated. The first optical quality, MOCVD grown LiNbO _3 films, having waveguiding losses of less than 2 dB/cm, were prepared. An important aspect of the SBN film growth studies involved finding a suitable single crystal substrate material. Mg

  16. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  17. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  18. BiFeO3 epitaxial thin films and devices: past, present and future

    Science.gov (United States)

    Sando, D.; Barthélémy, A.; Bibes, M.

    2014-11-01

    The celebrated renaissance of the multiferroics family over the past ten years has also been that of its most paradigmatic member, bismuth ferrite (BiFeO3). Known since the 1960s to be a high temperature antiferromagnet and since the 1970s to be ferroelectric, BiFeO3 only had its bulk ferroic properties clarified in the mid-2000s. It is however the fabrication of BiFeO3 thin films and their integration into epitaxial oxide heterostructures that have fully revealed its extraordinarily broad palette of functionalities. Here we review the first decade of research on BiFeO3 films, restricting ourselves to epitaxial structures. We discuss how thickness and epitaxial strain influence not only the unit cell parameters, but also the crystal structure, illustrated for instance by the discovery of the so-called T-like phase of BiFeO3. We then present its ferroelectric and piezoelectric properties and their evolution near morphotropic phase boundaries. Magnetic properties and their modification by thickness and strain effects, as well as optical parameters, are covered. Finally, we highlight various types of devices based on BiFeO3 in electronics, spintronics, and optics, and provide perspectives for the development of further multifunctional devices for information technology and energy harvesting.

  19. Enhanced polarization and dielectric properties of Pb(Zr1-xTix)O3 thin films

    Science.gov (United States)

    Ortega, N.; Kumar, Ashok; Katiyar, R. S.

    2008-10-01

    We report the fabrication of PbZr0.57Ti0.43O3 (PZT) thin films with preferential growth along (111) and random crystalline orientation on the platinized silicon substrates using pulsed laser deposition technique. X-ray diffraction patterns and surface morphology indicate increase in grain size and nucleation, which support better perovskite matrix with increase in annealing temperature. We observed large dielectric constant (˜4000) and enhanced remanent polarization 70 μC/cm2 at room temperature attributed to grain growth and intermetallic Pt-Pb transient phase. Frequency dependent polarization showed minor reduction in polarization above 10 kHz frequencies. Normalized fatigue characteristic of PZT thin films showed minimal 25% degradation in remanent polarization after 109 cycles, which may be useful for memory devices. ac conductivity spectra illustrated that anomaly near the phase transition temperature with activation energy (Ea˜0.60-0.75 eV) supports the intrinsic nature of ferroelectric phase transition.

  20. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    Jayakumar, S.; Kannan, M.D.; Prasanna, S.

    2012-01-01

    The objective of this book is to disseminate the most recent research in Thin Films, Nanomaterials, Corrosion and Metallurgy presented at the International Conference on Advanced Materials (ICAM 2011) held in PSG College of Technology, Coimbatore, India during 12-16 December 2011. The book is a compilation of 113 chapters written by active researchers providing information and critical insights into the recent advancements that have taken place. Important new applications are possible today in the fields of microelectronics, opto-electronics, metallurgy and energy by the application of thin films on solid surfaces. Recent progress in high vacuum technology and new materials has a remarkable effect in thin film quality and cost. This has led to the development of new single or multi-layered thin film devices with diverse applications in a multitude of production areas, such as optics, thermal barrier coatings and wear protections, enhancing service life of tools and to protect materials against thermal and atmospheric influence. On the other hand, thin film process techniques and research are strongly related to the basic research activities in nano technology, an increasingly important field with countless opportunities for applications due to the emergence of new properties at the nanoscale level. Materials and structures that are designed and fabricated at the nano scale level, offer the potential to produce new devices and processes that may enhance efficiencies and reduce costs in many areas, as photovoltaic systems, hydrogen storage, fuel cells and solar thermal systems. In the book, the contributed papers are classified under two sections i) thin films and ii) nanomaterials. The thin film section includes single or multi layer conducting, insulating or semiconducting films synthesized by a wide variety of physical or chemical techniques and characterized or analyzed for different applications. The nanomaterials section deals with novel or exciting materials

  1. Effects of Thickness, Pulse Duration, and Size of Strip Electrode on Ferroelectric Electron Emission of Lead Zirconate Titanate Films

    Science.gov (United States)

    Yaseen, Muhammad; Ren, Wei; Chen, Xiaofeng; Feng, Yujun; Shi, Peng; Wu, Xiaoqing

    2018-02-01

    Sol-gel-derived lead zirconate titanate (PZT) thin-film emitters with thickness up to 9.8 μm have been prepared on Pt/TiO2/SiO2/Si wafer via chemical solution deposition with/without polyvinylpyrrolidone (PVP) modification, and the relationship between the film thickness and electron emission investigated. Notable electron emission was observed on application of a trigger voltage of 120 V for PZT film with thickness of 1.1 μm. Increasing the film thickness decreased the threshold field to initiate electron emission for non-PVP-modified films. In contrast, the electron emission behavior of PVP-modified films did not show significant dependence on film thickness, probably due to their porous structure. The emission current increased with decreasing strip width and space between strips. Furthermore, it was observed that increasing the duration of the applied pulse increased the magnitude of the emission current. The stray field on the PZT film thickness was also calculated and found to increase with increasing ferroelectric sample thickness. The PZT emitters were found to be fatigue free up to 105 emission cycles. Saturated emission current of around 25 mA to 30 mA was achieved for the electrode pattern used in this work.

  2. BiFeO3 thin films: Novel effects

    Indian Academy of Sciences (India)

    photolithography followed by etching of the silver film. Saturation ... Fe in +3 state. Films thus obtained are therefore highly resistive (ρ ∼ 108–109 cm) and hence exhibit saturated ferroelectric hysteresis loop (figure 3). Anomaly in ... BiFeO3 bulk sample by Rogniskaya et al [4] had indicated abrupt change in lattice parame-.

  3. Interface depolarization field as common denominator of fatigue and size effect in Pb(Zr0.54Ti0.46)O3 ferroelectric thin film capacitors

    Science.gov (United States)

    Bouregba, R.; Sama, N.; Soyer, C.; Poullain, G.; Remiens, D.

    2010-05-01

    Dielectric, hysteresis and fatigue measurements are performed on Pb(Zr0.54Ti0.46)O3 (PZT) thin film capacitors with different thicknesses and different electrode configurations, using platinum and LaNiO3 conducting oxide. The data are compared with those collected in a previous work devoted to study of size effect by R. Bouregba et al., [J. Appl. Phys. 106, 044101 (2009)]. Deterioration of the ferroelectric properties, consecutive to fatigue cycling and thickness downscaling, presents very similar characteristics and allows drawing up a direct correlation between the two phenomena. Namely, interface depolarization field (Edep) resulting from interface chemistry is found to be the common denominator, fatigue phenomena is manifestation of strengthen of Edep in the course of time. Change in dielectric permittivity, in remnant and coercive values as well as in the shape of hysteresis loops are mediated by competition between degradation of dielectric properties of the interfaces and possible accumulation of interface space charge. It is proposed that presence in the band gap of trap energy levels with large time constant due to defects in small nonferroelectric regions at the electrode—PZT film interfaces ultimately governs the aging process. Size effect and aging process may be seen as two facets of the same underlying mechanism, the only difference lies in the observation time of the phenomena.

  4. High-performance ferroelectric and magnetoresistive materials for next-generation thermal detector arrays

    Science.gov (United States)

    Todd, Michael A.; Donohue, Paul P.; Watton, Rex; Williams, Dennis J.; Anthony, Carl J.; Blamire, Mark G.

    2002-12-01

    This paper discusses the potential thermal imaging performance achievable from thermal detector arrays and concludes that the current generation of thin-film ferroelectric and resistance bolometer based detector arrays are limited by the detector materials used. It is proposed that the next generation of large uncooled focal plane arrays will need to look towards higher performance detector materials - particularly if they aim to approach the fundamental performance limits and compete with cooled photon detector arrays. Two examples of bolometer thin-film materials are described that achieve high performance from operating around phase transitions. The material Lead Scandium Tantalate (PST) has a paraelectric-to-ferroelectric phase transition around room temperature and is used with an applied field in the dielectric bolometer mode for thermal imaging. PST films grown by sputtering and liquid-source CVD have shown merit figures for thermal imaging a factor of 2 to 3 times higher than PZT-based pyroelectric thin films. The material Lanthanum Calcium Manganite (LCMO) has a paramagnetic to ferromagnetic phase transition around -20oC. This paper describes recent measurements of TCR and 1/f noise in pulsed laser-deposited LCMO films on Neodymium Gallate substrates. These results show that LCMO not only has high TCR's - up to 30%/K - but also low 1/f excess noise, with bolometer merit figures at least an order of magnitude higher than Vanadium Oxide, making it ideal for the next generation of microbolometer arrays. These high performance properties come at the expense of processing complexities and novel device designs will need to be introduced to realize the potential of these materials in the next generation of thermal detectors.

  5. Synthesis of BiFeO{sub 3} thin films on single-terminated Nb : SrTiO{sub 3} (111) substrates by intermittent microwave assisted hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Velasco-Davalos, Ivan; Ambriz-Vargas, Fabian; Kolhatkar, Gitanjali; Thomas, Reji, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca; Ruediger, Andreas, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca [Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec, J3X1S2 (Canada)

    2016-06-15

    We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO{sub 3} (111) substrates and the deposition of ferroelectric BiFeO{sub 3} thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO{sub 3}){sup 4−} or Ti{sup 4+} layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d{sub 111}) and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO{sub 3} single crystal substrates. Multiferroic BiFeO{sub 3} thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO{sub 3} (111) substrates. Bi(NO{sub 3}){sub 3} and Fe(NO{sub 3}){sub 3} along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO{sub 3} films on Nb : SrTiO{sub 3} (100) substrates was verified by piezoresponse force microscopy.

  6. Lanthanum titanium perovskite compound: Thin film deposition and high frequency dielectric characterization

    International Nuclear Information System (INIS)

    Le Paven, C.; Lu, Y.; Nguyen, H.V.; Benzerga, R.; Le Gendre, L.; Rioual, S.; Benzegoutta, D.; Tessier, F.; Cheviré, F.

    2014-01-01

    Perovskite lanthanum titanium oxide thin films were deposited on (001) MgO, (001) LaAlO 3 and Pt(111)/TiO 2 /SiO 2 /(001)Si substrates by RF magnetron sputtering, using a La 2 Ti 2 O 7 homemade target sputtered under oxygen reactive plasma. The films deposited at 800 °C display a crystalline growth different than those reported on monoclinic ferroelectric La 2 Ti 2 O 7 films. X-ray photoelectron spectroscopy analysis shows the presence of titanium as Ti 4+ ions, with no trace of Ti 3+ , and provides a La/Ti ratio of 1.02. The depositions being performed from a La 2 Ti 2 O 7 target under oxygen rich plasma, the same composition (La 2 Ti 2 O 7 ) is proposed for the deposited films, with an unusual orthorhombic cell and Cmc2 1 space group. The films have a textured growth on MgO and Pt/Si substrates, and are epitaxially grown on LaAlO 3 substrate. The dielectric characterization displays stable values of the dielectric constant and of the losses in the frequency range [0.1–20] GHz. No variation of the dielectric constant has been observed when a DC electric field up to 250 kV/cm was applied, which does not match a classical ferroelectric behavior at high frequencies and room temperature for the proposed La 2 Ti 2 O 7 orthorhombic phase. At 10 GHz and room temperature, the dielectric constant of the obtained La 2 Ti 2 O 7 films is ε ∼ 60 and the losses are low (tanδ < 0.02). - Highlights: • Lanthanum titanium oxide films were deposited by reactive magnetron sputtering. • A La 2 Ti 2 O 7 chemical composition is proposed, with an unusual orthorhombic cell. • At 10 GHz, the dielectric losses are lower than 0.02. • No variation of the dielectric constant is observed under DC electric biasing

  7. Physical aspects of ferroelectric semiconductors for photovoltaic solar energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Varo, Pilar [Departamento de Electrónica y Tecnología de Computadores, CITIC-UGR, Universidad de Granada, 18071 Granada (Spain); Bertoluzzi, Luca [Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló (Spain); Bisquert, Juan, E-mail: bisquert@uji.es [Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló (Spain); Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Alexe, Marin [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Coll, Mariona [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193, Bellaterra, Catalonia (Spain); Huang, Jinsong [Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588-0656 (United States); Jimenez-Tejada, Juan Antonio [Departamento de Electrónica y Tecnología de Computadores, CITIC-UGR, Universidad de Granada, 18071 Granada (Spain); Kirchartz, Thomas [IEK5-Photovoltaik, Forschungszentrum Jülich, 52425 Jülich (Germany); Faculty of Engineering and CENIDE, University of Duisburg–Essen, Carl-Benz-Str. 199, 47057 Duisburg (Germany); Nechache, Riad; Rosei, Federico [INRS—Center Énergie, Matériaux et Télécommunications, Boulevard Lionel-Boulet, Varennes, Québec, J3X 1S2 (Canada); Yuan, Yongbo [Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588-0656 (United States)

    2016-10-07

    Solar energy conversion using semiconductors to fabricate photovoltaic devices relies on efficient light absorption, charge separation of electron–hole pair carriers or excitons, and fast transport and charge extraction to counter recombination processes. Ferroelectric materials are able to host a permanent electrical polarization which provides control over electrical field distribution in bulk and interfacial regions. In this review, we provide a critical overview of the physical principles and mechanisms of solar energy conversion using ferroelectric semiconductors and contact layers, as well as the main achievements reported so far. In a ferroelectric semiconductor film with ideal contacts, the polarization charge would be totally screened by the metal layers and no charge collection field would exist. However, real materials show a depolarization field, smooth termination of polarization, and interfacial energy barriers that do provide the control of interface and bulk electric field by switchable spontaneous polarization. We explore different phenomena as the polarization-modulated Schottky-like barriers at metal/ferroelectric interfaces, depolarization fields, vacancy migration, and the switchable rectifying behavior of ferroelectric thin films. Using a basic physical model of a solar cell, our analysis provides a general picture of the influence of ferroelectric effects on the actual power conversion efficiency of the solar cell device, and we are able to assess whether these effects or their combinations are beneficial or counterproductive. We describe in detail the bulk photovoltaic effect and the contact layers that modify the built-in field and the charge injection and separation in bulk heterojunction organic cells as well as in photocatalytic and water splitting devices. We also review the dominant families of ferroelectric materials that have been most extensively investigated and have provided the best photovoltaic performance.

  8. Physical aspects of ferroelectric semiconductors for photovoltaic solar energy conversion

    International Nuclear Information System (INIS)

    Lopez-Varo, Pilar; Bertoluzzi, Luca; Bisquert, Juan; Alexe, Marin; Coll, Mariona; Huang, Jinsong; Jimenez-Tejada, Juan Antonio; Kirchartz, Thomas; Nechache, Riad; Rosei, Federico; Yuan, Yongbo

    2016-01-01

    Solar energy conversion using semiconductors to fabricate photovoltaic devices relies on efficient light absorption, charge separation of electron–hole pair carriers or excitons, and fast transport and charge extraction to counter recombination processes. Ferroelectric materials are able to host a permanent electrical polarization which provides control over electrical field distribution in bulk and interfacial regions. In this review, we provide a critical overview of the physical principles and mechanisms of solar energy conversion using ferroelectric semiconductors and contact layers, as well as the main achievements reported so far. In a ferroelectric semiconductor film with ideal contacts, the polarization charge would be totally screened by the metal layers and no charge collection field would exist. However, real materials show a depolarization field, smooth termination of polarization, and interfacial energy barriers that do provide the control of interface and bulk electric field by switchable spontaneous polarization. We explore different phenomena as the polarization-modulated Schottky-like barriers at metal/ferroelectric interfaces, depolarization fields, vacancy migration, and the switchable rectifying behavior of ferroelectric thin films. Using a basic physical model of a solar cell, our analysis provides a general picture of the influence of ferroelectric effects on the actual power conversion efficiency of the solar cell device, and we are able to assess whether these effects or their combinations are beneficial or counterproductive. We describe in detail the bulk photovoltaic effect and the contact layers that modify the built-in field and the charge injection and separation in bulk heterojunction organic cells as well as in photocatalytic and water splitting devices. We also review the dominant families of ferroelectric materials that have been most extensively investigated and have provided the best photovoltaic performance.

  9. Organic electronic memory based on a ferroelectric polymer

    Energy Technology Data Exchange (ETDEWEB)

    Kalbitz, R; Fruebing, P; Gerhard, R [Department of Physics and Astronomy, University of Potsdam, Karl-Liebknecht Str., 24-25, 14476 Potsdam (Germany); Taylor, D M, E-mail: d.m.taylor@bangor.ac.uk [School of Electronic Engineering, Bangor University, Dean Street, Bangor, Gwynedd LL57 1UT (United Kingdom)

    2011-06-23

    Measurements of the capacitance of metal-insulator-semiconductor capacitors and the output characteristics of thin film transistors based on poly(3-hexylthiophene) as the active semiconductor and poly(vinylidenefluoride-trifluoroethylene) as the gate insulator show that ferroelectric polarisation in the insulator is stable but that its effect when poled by depletion voltages is partially neutralised by trapping of electrons at or near the semiconductor interface. Nevertheless, the combination of materials is capable of providing an adequate memory function.

  10. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  11. Multiferroic fluoride BaCoF4 Thin Films Grown Via Molecular Beam Epitaxy

    Science.gov (United States)

    Borisov, Pavel; Johnson, Trent; García-Castro, Camilo; Kc, Amit; Schrecongost, Dustin; Cen, Cheng; Romero, Aldo; Lederman, David

    Multiferroic materials exhibit exciting physics related to the simultaneous presence of multiple long-range orders, in many cases consisting of antiferromagnetic (AF) and ferroelectric (FE) orderings. In order to provide a new, promising route for fluoride-based multiferroic material engineering, we grew multiferroic fluoride BaCoF4 in thin film form on Al2O3 (0001) substrates by molecular beam epitaxy. The films grow with the orthorhombic b-axis out-of-plane and with three in-plane structural twin domains along the polar c-axis directions. The FE ordering in thin films was verified by FE remanent hysteresis loops measurements at T = 14 K and by room temperature piezoresponse force microscopy (PFM). An AF behavior was found below Neel temperature TN ~ 80 K, which is in agreement with the bulk properties. At lower temperatures two additional magnetic phase transitions at 19 K and 41 K were found. First-principles calculations demonstrated that the growth strain applied to the bulk BaCoF4 indeed favors two canted spin orders, along the b- and a-axes, respectively, in addition to the main AF spin order along the c-axis. Supported by FAME (Contract 2013-MA-2382), WV Research Challenge Grant (HEPC.dsr.12.29), and DMREF-NSF 1434897.

  12. Comparative microstructure and electrical property studies of lead scandium tantalate thin films as prepared by LDCVD, sol-gel and sputtering techniques

    International Nuclear Information System (INIS)

    Huang, Z; Donohue, P P; Zhang, Q; Williams, D J; Anthony, C J; Whatmore, R W; Todd, M A

    2003-01-01

    Lead scandium tantalate (PST) thin films for uncooled infrared (IR) detector applications have been deposited by liquid delivery chemical vapour deposition (LDCVD), sputtering and sol-gel techniques. The sol-gel and sputtered films were deposited at low temperature into a non-ferroelectric phase with the required perovskite structure being formed using a high temperature rapid thermal anneal (RTA). In contrast to this, the LDCVD films were deposited at high temperature directly into the perovskite phase but were found to still require a high temperature RTA step to optimize their merit for IR detection. Detailed structural and electrical characterization of the PST films deposited by these different methods have revealed that there is no simple relationship between microstructure and electrical properties. The sol-gel and LDCVD techniques produce thin films with excellent microstructures, as determined by x-ray diffraction analysis and transmission electron microscopy, but inferior electrical properties and relatively low merit figures. By contrast, the sputtered and then rapid thermal annealed films have inferior microstructures, characterized by extensive voiding, but excellent electrical properties and high merit figures

  13. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  14. Thin Film Photovoltaic Partnership Project | Photovoltaic Research | NREL

    Science.gov (United States)

    Thin Film Photovoltaic Partnership Project Thin Film Photovoltaic Partnership Project NREL's Thin Film Photovoltaic (PV) Partnership Project led R&D on emerging thin-film solar technologies in the United States from 1994 to 2009. The project made many advances in thin-film PV technologies that allowed

  15. Growth and characterization of epitaxial thin films and multiferroic heterostructures of ferromagnetic and ferroelectric materials

    Science.gov (United States)

    Mukherjee, Devajyoti

    Multiferroic materials exhibit unique properties such as simultaneous existence of two or more of coupled ferroic order parameters (ferromagnetism, ferroelectricity, ferroelasticity or their anti-ferroic counterparts) in a single material. Recent years have seen a huge research interest in multiferroic materials for their potential application as high density non-volatile memory devices. However, the scarcity of these materials in single phase and the weak coupling of their ferroic components have directed the research towards multiferroic heterostructures. These systems operate by coupling the magnetic and electric properties of two materials, generally a ferromagnetic material and a ferroelectric material via strain. In this work, horizontal heterostructures of composite multiferroic materials were grown and characterized using pulsed laser ablation technique. Alternate magnetic and ferroelectric layers of cobalt ferrite and lead zirconium titanate, respectively, were fabricated and the coupling effect was studied by X-ray stress analysis. It was observed that the interfacial stress played an important role in the coupling effect between the phases. Doped zinc oxide (ZnO) heterostructures were also studied where the ferromagnetic phase was a layer of manganese doped ZnO and the ferroelectric phase was a layer of vanadium doped ZnO. For the first time, a clear evidence of possible room temperature magneto-elastic coupling was observed in these heterostructures. This work provides new insight into the stress mediated coupling mechanisms in composite multiferroics.

  16. Rewritable ferroelectric vortex pairs in BiFeO3

    Science.gov (United States)

    Li, Yang; Jin, Yaming; Lu, Xiaomei; Yang, Jan-Chi; Chu, Ying-Hao; Huang, Fengzhen; Zhu, Jinsong; Cheong, Sang-Wook

    2017-08-01

    Ferroelectric vortex in multiferroic materials has been considered as a promising alternative to current memory cells for the merit of high storage density. However, the formation of regular natural ferroelectric vortex is difficult, restricting the achievement of vortex memory device. Here, we demonstrated the creation of ferroelectric vortex-antivortex pairs in BiFeO3 thin films by using local electric field. The evolution of the polar vortex structure is studied by piezoresponse force microscopy at nanoscale. The results reveal that the patterns and stability of vortex structures are sensitive to the poling position. Consecutive writing and erasing processes cause no influence on the original domain configuration. The Z4 proper coloring vortex-antivortex network is then analyzed by graph theory, which verifies the rationality of artificial vortex-antivortex pairs. This study paves a foundation for artificial regulation of vortex, which provides a possible pathway for the design and realization of non-volatile vortex memory devices and logical devices.

  17. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  18. Microstructure of epitaxial SrRuO 3 thin films on MgO substrates

    Science.gov (United States)

    Ai, Wan Yong; Zhu, Jun; Zhang, Ying; Li, Yan Rong; Liu, Xing Zhao; Wei, Xian Hua; Li, Jin Long; Zheng, Liang; Qin, Wen Feng; Liang, Zhu

    2006-09-01

    SrRuO 3 thin films have been grown on singular (1 0 0) MgO substrates using pulsed laser deposition (PLD) in 30 Pa oxygen ambient and at a temperature of 400-700 °C. Ex situ reflection high-energy electron diffraction (RHEED) as well as X-ray diffraction (XRD) θ/2 θ scan indicated that the films deposited above 650 °C were well crystallized though they had a rough surface as shown by atom force microscopy (AFM). XRD Φ scans revealed that these films were composed of all three different types of orientation domains, which was further confirmed by the RHEED patterns. The heteroepitaxial relationship between SrRuO 3 and MgO was found to be [1 1 0] SRO//[1 0 0] MgO and 45°-rotated cube-on-cube [0 0 1] SRO//[1 0 0] MgO. These domain structures and surface morphology are similar to that of ever-reported SrRuO 3 thin films deposited on the (0 0 1) LaAlO 3 substrates, and different from those deposited on (0 0 1) SrTiO 3 substrates that have an atomically flat surface and are composed of only the [1 1 0]-type domains. The reason for this difference was ascribed to the effect of lattice mismatch across the film/substrate interface. The room temperature resistivity of SrRuO 3 films fabricated at 700 °C was 300 μΩ cm. Therefore, epitaxial SrRuO 3 films on MgO substrate could serve as a promising candidate of electrode materials for the fabrication of ferroelectric or dielectric films.

  19. Influence of applied electric field annealing on the microwave properties of (Ba0.5Sr0.5)TiO3 thin films

    Science.gov (United States)

    Cho, Kwang-Hwan; Lee, Chil-Hyoung; Kang, Chong-Yun; Yoon, Seok-Jin; Lee, Young-Pak

    2007-04-01

    The effect of heat treatment in electric field on the structure and dielectric properties at microwave range of rf magnetron sputtering derived (Ba0.5Sr0.5)TiO3 thin films have been studied. It has been demonstrated that postannealing in the proper electric field can increase the dielectric constant and the tunability. The increased out-of-plane lattice constant in the electric-annealed films indicated the formation of small polar regions with tetragonal structure, which are responsible for the increased dielectric constant and tunability. It was proposed that the segregation of Ti3+ ions caused by electric annealing could induce the formation of BaTiO3-like regions, which are ferroelectric at room temperature. And in dielectric loss, as the Ti-O bonding lengths increase, the energy scattering on the ferroelectric mode also increases. So, the value of dielectric loss is slightly increased.

  20. Ferroelectric and Piezoelectric properties of (111) oriented lanthanum modified lead zirconate titanate film

    International Nuclear Information System (INIS)

    Dutta, Soma; Antony Jeyaseelan, A.; Sruthi, S.

    2014-01-01

    Lanthanum modified lead zirconate titanate (PLZT) thick film with molecular formula of Pb 0.92 La 0.08 (Zr 0.52 Ti 0.48 ) 0.98 O 3 was grown preferentially along (111) direction on Pt/SiO 2 /Si (platinum/silicon oxide/silicon) substrate by spin coating of chemical solution. The directional growth of the film was facilitated by platinum (Pt) (111) template and rapid thermal annealing. X-ray diffraction pattern and atomic force microscopy revealed the preferential growth of the PLZT film. The film was characterized for ferroelectric and detailed piezoelectric properties in a parallel plate capacitor (metal–PLZT–metal) configuration. Ferroelectric characterization of the film showed saturated hysteresis loop with remanent polarization and coercive electric field values of 10.14 μC/cm 2 and 42 kV/cm, respectively, at an applied field of 300 kV/cm. Longitudinal piezoelectric coefficient (d 33,f ) was measured by employing converse piezoelectric effect where electrical charge response and displacement were measured with electrical voltage excitation on the sample electrodes. The effective transverse piezoelectric coefficient (e 31,f ) was derived from charge measurement with an applied mechanical excitation strain by using the four point bending method. d 33,f and e 31,f coefficients of PLZT films were found to be 380 pm/V and − 0.831 C/m 2 respectively. - Highlights: • PLZT (111) film is prepared by spin coating of chemical sol on Pt (111) template. • Piezoelectric d 33 value (380 pm/V) of PLZT film is found 20% higher than PZT. • Transverse piezocoefficient e 31,f of PLZT film is reported for the first time

  1. Characterization of organic thin films

    CERN Document Server

    Ulman, Abraham; Evans, Charles A

    2009-01-01

    Thin films based upon organic materials are at the heart of much of the revolution in modern technology, from advanced electronics, to optics to sensors to biomedical engineering. This volume in the Materials Characterization series introduces the major common types of analysis used in characterizing of thin films and the various appropriate characterization technologies for each. Materials such as Langmuir-Blodgett films and self-assembled monolayers are first introduced, followed by analysis of surface properties and the various characterization technologies used for such. Readers will find detailed information on: -Various spectroscopic approaches to characterization of organic thin films, including infrared spectroscopy and Raman spectroscopy -X-Ray diffraction techniques, High Resolution EELS studies, and X-Ray Photoelectron Spectroscopy -Concise Summaries of major characterization technologies for organic thin films, including Auger Electron Spectroscopy, Dynamic Secondary Ion Mass Spectrometry, and Tra...

  2. Organometal Halide Perovskite Solar Absorbers and Ferroelectric Nanocomposites for Harvesting Solar Energy

    Science.gov (United States)

    Hettiarachchi, Chaminda Lakmal

    Organometal halide perovskite absorbers such as methylammonium lead iodide chloride (CH3NH3PbI3-xClx), have emerged as an exciting new material family for photovoltaics due to its appealing features that include suitable direct bandgap with intense light absorbance, band gap tunability, ultra-fast charge carrier generation, slow electron-hole recombination rates, long electron and hole diffusion lengths, microsecond-long balanced carrier mobilities, and ambipolarity. The standard method of preparing CH3NH3PbI3-xClx perovskite precursors is a tedious process involving multiple synthesis steps and, the chemicals being used (hydroiodic acid and methylamine) are quite expensive. This work describes a novel, single-step, simple, and cost-effective solution approach to prepare CH3NH3PbI3-xClx thin films by the direct reaction of the commercially available CH3NH 3Cl (or MACl) and PbI2. A detailed analysis of the structural and optical properties of CH3NH3PbI3-xCl x thin films deposited by aerosol assisted chemical vapor deposition is presented. Optimum growth conditions have been identified. It is shown that the deposited thin films are highly crystalline with intense optical absorbance. Charge carrier separation of these thin films can be enhanced by establishing a local internal electric field that can reduce electron-hole recombination resulting in increased photo current. The intrinsic ferroelectricity in nanoparticles of Barium Titanate (BaTiO3 -BTO) embedded in the solar absorber can generate such an internal field. A hybrid structure of CH3NH 3PbI3-xClx perovskite and ferroelectric BTO nanocomposite FTO/TiO2/CH3NH3PbI3-xClx : BTO/P3HT/Cu as a new type of photovoltaic device is investigated. Aerosol assisted chemical vapor deposition process that is scalable to large-scale manufacturing was used for the growth of the multilayer structure. TiO 2 and P3HT with additives were used as ETL and HTL respectively. The growth process of the solar absorber layer includes the

  3. Chemical composition and deformation-induced stresses in ferroelectric films of barium-strontium titanate

    International Nuclear Information System (INIS)

    Karmanenko, S.F.; Dedyk, A.I.; Isakov, N.N.; Sakharov, V.I.; Semenov, A.A.; Serenkov, I.T.; Ter-Martirosyan, L.T.

    1999-01-01

    Influence of the ratio of cationic components and inner deformation-induced stresses on critical temperature (T c ) and dielectric characteristics of ferroelectric films Ba x Sr 1-x TiO 3 grown on α-Al 2 O 3 [1012] and LaAlO 3 substrates was studied. Diagnosis by means of ion backscattering permitted ascertaining the deficiency of barium in the films near the surface layer, as well as differences in their structural quality [ru

  4. Al-, Y-, and La-doping effects favoring intrinsic and field induced ferroelectricity in HfO2: A first principles study

    Science.gov (United States)

    Materlik, Robin; Künneth, Christopher; Falkowski, Max; Mikolajick, Thomas; Kersch, Alfred

    2018-04-01

    III-valent dopants have shown to be most effective in stabilizing the ferroelectric, crystalline phase in atomic layer deposited, polycrystalline HfO2 thin films. On the other hand, such dopants are commonly used for tetragonal and cubic phase stabilization in ceramic HfO2. This difference in the impact has not been elucidated so far. The prospect is a suitable doping to produce ferroelectric HfO2 ceramics with a technological impact. In this paper, we investigate the impact of Al, Y, and La doping, which have experimentally proven to stabilize the ferroelectric Pca21 phase in HfO2, in a comprehensive first-principles study. Density functional theory calculations reveal the structure, formation energy, and total energy of various defects in HfO2. Most relevant are substitutional electronically compensated defects without oxygen vacancy, substitutional mixed compensated defects paired with a vacancy, and ionically compensated defect complexes containing two substitutional dopants paired with a vacancy. The ferroelectric phase is strongly favored with La and Y in the substitutional defect. The mixed compensated defect favors the ferroelectric phase as well, but the strongly favored cubic phase limits the concentration range for ferroelectricity. We conclude that a reduction of oxygen vacancies should significantly enhance this range in Y doped HfO2 thin films. With Al, the substitutional defect hardly favors the ferroelectric phase before the tetragonal phase becomes strongly favored with the increasing concentration. This could explain the observed field induced ferroelectricity in Al-doped HfO2. Further Al defects are investigated, but do not favor the f-phase such that the current explanation remains incomplete for Al doping. According to the simulation, doping alone shows clear trends, but is insufficient to replace the monoclinic phase as the ground state. To explain this fact, some other mechanism is needed.

  5. Self-Limited Growth in Pentacene Thin Films.

    Science.gov (United States)

    Pachmajer, Stefan; Jones, Andrew O F; Truger, Magdalena; Röthel, Christian; Salzmann, Ingo; Werzer, Oliver; Resel, Roland

    2017-04-05

    Pentacene is one of the most studied organic semiconducting materials. While many aspects of the film formation have already been identified in very thin films, this study provides new insight into the transition from the metastable thin-film phase to bulk phase polymorphs. This study focuses on the growth behavior of pentacene within thin films as a function of film thickness ranging from 20 to 300 nm. By employing various X-ray diffraction methods, combined with supporting atomic force microscopy investigations, one crystalline orientation for the thin-film phase is observed, while three differently tilted bulk phase orientations are found. First, bulk phase crystallites grow with their 00L planes parallel to the substrate surface; second, however, crystallites tilted by 0.75° with respect to the substrate are found, which clearly dominate the former in ratio; third, a different bulk phase polymorph with crystallites tilted by 21° is found. The transition from the thin-film phase to the bulk phase is rationalized by the nucleation of the latter at crystal facets of the thin-film-phase crystallites. This leads to a self-limiting growth of the thin-film phase and explains the thickness-dependent phase behavior observed in pentacene thin films, showing that a large amount of material is present in the bulk phase much earlier during the film growth than previously thought.

  6. Phase transition in lead titanate thin films: a Brillouin study

    International Nuclear Information System (INIS)

    Kuzel, P; Dugautier, C; Moch, P; Marrec, F Le; Karkut, M G

    2002-01-01

    The elastic properties of both polycrystalline and epitaxial PbTiO 3 (PTO) thin films are studied using Brillouin scattering spectroscopy. The epitaxial PTO films were prepared by pulsed laser ablation on (1) a [0 0 1] single crystal of SrTiO 3 (STO) doped with Nb and (2) a [0 0 1] STO buffered with a layer of YBa 2 Cu 3 O 7 . The polycrystalline PTO films were prepared by sol-gel on a Si substrate buffered with TiO 2 and Pt layers. The data analysis takes into account the ripple and the elasto-optic contributions. The latter significantly affects the measured spectra since it gives rise to a Love mode in the p-s scattering geometry. At room temperature, the spectra of the epitaxially grown samples are interpreted using previously published elastic constants of PTO single crystals. Sol-gel samples exhibit appreciable softening of the effective elastic properties compared to PTO single crystals: this result is explained by taking into account the random orientation of the microscopic PTO grains. For both the polycrystalline and the epitaxial films we have determined that the piezoelectric terms do not contribute to the spectra. The temperature dependence of the spectra shows strong anomalies of the elastic properties near the ferroelectric phase transition. Compared to the bulk, T C is higher in the sol-gel films, while in the epitaxial films the sign of the T C shift depends on the underlying material

  7. Characterisation of lead barium zirconate thin films for utilisation of the electrocaloric effect

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, C.P., E-mail: c.p.shaw@cranfield.ac.uk [Surface Engineering and Nanotechnology Institute, Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Zhang, Qi, E-mail: q.zhang@cranfield.ac.uk [Surface Engineering and Nanotechnology Institute, Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Correia, T.M., E-mail: Tatiana.correia@ktn-uk.org [Knowledge Transfer Network (United Kingdom); Weaver, P.M., E-mail: paul.weaver@innotecuk.com [InotekUK (United Kingdom)

    2016-08-01

    Characterisation of a composition of Lead Barium Zirconate thin films deposited by a spin coating sol-gel process onto platinised silicon substrates has been undertaken to investigate a potential application utilising the reported electrocaloric properties of the material. Xray diffraction studies revealed that above 700 °C the presence of pyrochlore phase was replaced by ferroelectric phase but the identification of antiferroelectric phases previously reported could not be identified. Wet etching of the films produced an insoluble residue containing only evidence of zirconium out of the original three metals, which resembled a skeletal structure similar to the original rosette morphology of the annealed films. Elemental analysis of the annealed films using EDX indicated a non-target Pb:Ba:Zr ratio, which suggested a reduced Zr content of the films. “Solution-like” rather than “sol-like” nature of the spin coated sol and phase boundary proximity are proposed for reported observations, and a mechanism is proposed to account for the unusual observed trend in dielectric constant. - Highlights: • Characterisation of sol-gel deposited Lead barium zirconnate films. • Absence of previously reported antiferroelectric phase. • Identification of proposed non-PBZ phase. • Anomalous increase in film capacitance with thickness interpreted.

  8. Fatigue and retention in ferroelectric Y-Ba-Cu-O/Pb-Zr-Ti-O/Y-Ba-Cu-O heterostructures

    Science.gov (United States)

    Ramesh, R.; Chan, W. K.; Wilkens, B.; Gilchrist, H.; Sands, T.; Tarascon, J. M.; Keramidas, V. G.; Fork, D. K.; Lee, J.; Safari, A.

    1992-09-01

    Fatigue and retention characteristics of ferroelectric lead zirconate titanate thin films grown with Y-Ba-Cu-O(YBCO) thin-film top and bottom electrodes are found to be far superior to those obtained with conventional Pt top electrodes. The heterostructures reported here have been grown in situ by pulsed laser deposition on yttria-stabilized ZrO2 buffer [100] Si and on [001] LaAlO3. Both the a- and c-axis orientations of the YBCO lattice have been used as electrodes. They were prepared using suitable changes in growth conditions.

  9. Modeling of Structure Effect for Ferroelectric Capacitor Based on Poly(vinylidene fluoride-trifluoroethylene Ultrathin Films

    Directory of Open Access Journals (Sweden)

    Long Li

    2017-12-01

    Full Text Available The characteristics of ferroelectric capacitors with poly(vinylidene fluoride-trifluoroethlene (P(VDF-TrFE films have been studied at different structures of cell electrodes. It is suggested that the effect of electrode structures could induce changes of performance. Remarkably, cells with line electrodes display a better polarization and fatigue resistance than those with flat electrodes. For P(VDF-TrFE ultrathin films with different electrode structures, the models of charge compensation mechanism for depolarization field and domain fatigue decomposition are used to explain the effect of electrode structure. Furthermore, the driving voltage based on normal speed-functionality is designed, and the testing results show that the line electrode structure could induce a robust switching, which is determined by the free charges concentration in active layer. These findings provide an effective route to design the optimum structure for a ferroelectric capacitor based on P(VDF-TrFE copolymer ultrathin film.

  10. Nanodomain Engineering in Ferroelectric Capacitors with Graphene Electrodes.

    Science.gov (United States)

    Lu, Haidong; Wang, Bo; Li, Tao; Lipatov, Alexey; Lee, Hyungwoo; Rajapitamahuni, Anil; Xu, Ruijuan; Hong, Xia; Farokhipoor, Saeedeh; Martin, Lane W; Eom, Chang-Beom; Chen, Long-Qing; Sinitskii, Alexander; Gruverman, Alexei

    2016-10-12

    Polarization switching in ferroelectric capacitors is typically realized by application of an electrical bias to the capacitor electrodes and occurs via a complex process of domain structure reorganization. As the domain evolution in real devices is governed by the distribution of the nucleation centers, obtaining a domain structure of a desired configuration by electrical pulsing is challenging, if not impossible. Recent discovery of polarization reversal via the flexoelectric effect has opened a possibility for deterministic control of polarization in ferroelectric capacitors. In this paper, we demonstrate mechanical writing of arbitrary-shaped nanoscale domains in thin-film ferroelectric capacitors with graphene electrodes facilitated by a strain gradient induced by a tip of an atomic force microscope (AFM). A phase-field modeling prediction of a strong effect of graphene thickness on the threshold load required to initiate mechanical switching has been confirmed experimentally. Deliberate voltage-free domain writing represents a viable approach for development of functional devices based on domain topology and electronic properties of the domains and domain walls.

  11. Electric field cycling behavior of ferroelectric hafnium oxide.

    Science.gov (United States)

    Schenk, Tony; Schroeder, Uwe; Pešić, Milan; Popovici, Mihaela; Pershin, Yuriy V; Mikolajick, Thomas

    2014-11-26

    HfO2 based ferroelectrics are lead-free, simple binary oxides with nonperovskite structure and low permittivity. They just recently started attracting attention of theoretical groups in the fields of ferroelectric memories and electrostatic supercapacitors. A modified approach of harmonic analysis is introduced for temperature-dependent studies of the field cycling behavior and the underlying defect mechanisms. Activation energies for wake-up and fatigue are extracted. Notably, all values are about 100 meV, which is 1 order of magnitude lower than for conventional ferroelectrics like lead zirconate titanate (PZT). This difference is mainly atttributed to the one to two orders of magnitude higher electric fields used for cycling and to the different surface to volume ratios between the 10 nm thin films in this study and the bulk samples of former measurements or simulations. Moreover, a new, analog-like split-up effect of switching peaks by field cycling is discovered and is explained by a network model based on memcapacitive behavior as a result of defect redistribution.

  12. Multiferroicity in oxide thin films and heterostructures

    International Nuclear Information System (INIS)

    Glavic, Artur

    2012-01-01

    In this work a variety of different systems of transition metal oxides ABO 3 (perovskite materials, where B stands for a transition metal and A for a rare earth element) were produced as thin films and heterostructures and analyzed for the structural, magnetic and ferroelectric properties. For the epitaxial film preparation mostly pulse laser deposition (PLD) was applied. For one series high pressure oxide sputter deposition was used as well. The bulk multiferroics TbMnO 3 and DyMnO 3 , which develop their electric polarization due to a cycloidal magnetic order, have been prepared as single layers with thicknesses between 2 and 200 nm on YAlO 3 substrates using PLD and sputter deposition. The structural characterization of the surfaces and crystal structure where performed using X-ray reflectometry and diffraction, respectively. These yielded low surface roughness and good epitaxial growth. The magnetic behavior was macroscopically measured with SQUID magnetometry and microscopically with polarized neutron diffraction and resonant magnetic X-ray scattering. While all investigated samples showed antiferromagnetic order, comparable with the collinear magnetic phase of their bulk materials, only the sputter deposited samples exhibited the multiferroic low temperature cycloidal order. The investigation of the optical second harmonic generation in a TbMnO 3 sample could proof the presence of a ferroelectric order in the low temperature phase. The respective transition temperatures of the thin films have been very similar to those of the bulk materials. In contrast an increase in the rare earth ordering temperature has been observed, which reduces the Mn order slightly, an effect not known from bulk TbMnO 3 crystals. The coupling of the antiferromagnetic order in TbMnO 3 to ferromagnetic layers of LaCoO 3 was investigated in super-lattices containing 20 bilayers produced with PLD on the same substrates. The SQUID magnetometry yielded a strong influence of the

  13. Thin films for precision optics

    International Nuclear Information System (INIS)

    Araujo, J.F.; Maurici, N.; Castro, J.C. de

    1983-01-01

    The technology of producing dielectric and/or metallic thin films for high precision optical components is discussed. Computer programs were developed in order to calculate and register, graphically, reflectance and transmittance spectra of multi-layer films. The technology of vacuum evaporation of several materials was implemented in our thin-films laboratory; various films for optics were then developed. The possibility of first calculate film characteristics and then produce the film is of great advantage since it reduces the time required to produce a new type of film and also reduces the cost of the project. (C.L.B.) [pt

  14. Interfacial Nb-substitution induced anomalous enhancement of polarization and conductivity in BaTiO3 ferroelectric tunnel junctions

    Directory of Open Access Journals (Sweden)

    H. F. Li

    2014-12-01

    Full Text Available Using density functional theory (DFT method combined with non-equilibrium Green’s function approach, we systematically investigated the structural, ferroelectric and electronic transport properties of Pt/BaTiO3/Pt ferroelectric tunnel junctions (FTJ with the interface atomic layers doped by charge neutral NbTi substitution. It is found that interfacial NbTi substitution will produce several anomalous effects such as the vanishing of ferroelectric critical thickness and the decrease of junction resistance against tunneling current. Consequently, the thickness of the ferroelectric thin film (FTF in the FTJ can be reduced, and both the electroresistance effect and sensitivity to external bias of the FTJ are enhanced. Our calculations indicate that the enhancements of conductivity and ferroelectric distortion can coexist in FTJs, which should be important for applications of functional electronic devices based on FTJs.

  15. Ferroelectricity-induced resistive switching in Pb(Zr0.52Ti0.48)O3/Pr0.7Ca0.3MnO3/Nb-doped SrTiO3 epitaxial heterostructure

    Science.gov (United States)

    Md. Sadaf, Sharif; Mostafa Bourim, El; Liu, Xinjun; Hasan Choudhury, Sakeb; Kim, Dong-Wook; Hwang, Hyunsang

    2012-03-01

    We investigated the effect of a ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin film on the generation of resistive switching in a stacked Pr0.7Ca0.3MnO3 (PCMO)/Nb-doped SrTiO3 (Nb:STO) heterostructure forming a p-n junction. To promote the ferroelectric effect, the thin PZT active layer was deposited on an epitaxially grown p-type PCMO film on a lattice-matched n-type Nb:STO single crystal. It was concluded that the observed resistive switching behavior in the all-perovskite Pt/PZT/PCMO/Nb:STO heterostructure was related to the modulation of PCMO/Nb:STO p-n junction's depletion width, which was caused either by the PZT ferroelectric polarization field effect, the electrochemical drift of oxygen ions under an electric field, or both simultaneously.

  16. Analysis of Hard Thin Film Coating

    Science.gov (United States)

    Shen, Dashen

    1998-01-01

    MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

  17. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with

  18. Ferroelectric and Piezoelectric properties of (111) oriented lanthanum modified lead zirconate titanate film

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Soma, E-mail: som@nal.res.in; Antony Jeyaseelan, A.; Sruthi, S.

    2014-07-01

    Lanthanum modified lead zirconate titanate (PLZT) thick film with molecular formula of Pb{sub 0.92}La{sub 0.08}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.98}O{sub 3} was grown preferentially along (111) direction on Pt/SiO{sub 2}/Si (platinum/silicon oxide/silicon) substrate by spin coating of chemical solution. The directional growth of the film was facilitated by platinum (Pt) (111) template and rapid thermal annealing. X-ray diffraction pattern and atomic force microscopy revealed the preferential growth of the PLZT film. The film was characterized for ferroelectric and detailed piezoelectric properties in a parallel plate capacitor (metal–PLZT–metal) configuration. Ferroelectric characterization of the film showed saturated hysteresis loop with remanent polarization and coercive electric field values of 10.14 μC/cm{sup 2} and 42 kV/cm, respectively, at an applied field of 300 kV/cm. Longitudinal piezoelectric coefficient (d{sub 33,f}) was measured by employing converse piezoelectric effect where electrical charge response and displacement were measured with electrical voltage excitation on the sample electrodes. The effective transverse piezoelectric coefficient (e{sub 31,f}) was derived from charge measurement with an applied mechanical excitation strain by using the four point bending method. d{sub 33,f} and e{sub 31,f} coefficients of PLZT films were found to be 380 pm/V and − 0.831 C/m{sup 2} respectively. - Highlights: • PLZT (111) film is prepared by spin coating of chemical sol on Pt (111) template. • Piezoelectric d{sub 33} value (380 pm/V) of PLZT film is found 20% higher than PZT. • Transverse piezocoefficient e{sub 31,f} of PLZT film is reported for the first time.

  19. Thin-Film Material Science and Processing | Materials Science | NREL

    Science.gov (United States)

    Thin-Film Material Science and Processing Thin-Film Material Science and Processing Photo of a , a prime example of this research is thin-film photovoltaics (PV). Thin films are important because cadmium telluride thin film, showing from top to bottom: glass, transparent conducting oxide (thin layer

  20. Optimization of the low-temperature MOCVD process for PZT thin films

    CERN Document Server

    Wang, C H; Choi, D J

    2000-01-01

    Pb(Zr sub X Ti sub 1 sub - sub X)O sub 3 (PZT) thin films of about 0.34 nm were successfully grown at a low temperature of 500 .deg. C by metalorganic chemical vapor deposition with a beta-diketonate complex of Pb(tmhd) sub 2 , zirconium t-butoxide, and titanium isopropoxide as source precursors. Ferroelectric capacitors of a Pt/PZT/Pt configuration were fabricated, and their structural and electrical properties were investigated as a function of the input Pb/(Zr+Ti) and Zr/(Zr+Ti) source ratios. The structure of the as-grown films at 500 .deg. C changed from tetragonal to pseudocubic with increasing the Zr/(Zr+Ti) ratio above an input Pb/(Zr+Ti) source ratio of 5.0 while a 2nd phase of ZrO sub 2 was only observed below Pb/(Zr+Ti) ratio of 5.0, regardless of the Zr/(Zr+Ti) ratio. The dielectric constant and loss of the PZT films were 150-1200 and 0.01-0.04 at 100 kHz, respectively, Leakage current densities decreased with increasing the Zr/(Zr+Ti) ratio. The process window for growing a single phase PZT is ve...

  1. Nanocrystal thin film fabrication methods and apparatus

    Science.gov (United States)

    Kagan, Cherie R.; Kim, David K.; Choi, Ji-Hyuk; Lai, Yuming

    2018-01-09

    Nanocrystal thin film devices and methods for fabricating nanocrystal thin film devices are disclosed. The nanocrystal thin films are diffused with a dopant such as Indium, Potassium, Tin, etc. to reduce surface states. The thin film devices may be exposed to air during a portion of the fabrication. This enables fabrication of nanocrystal-based devices using a wider range of techniques such as photolithography and photolithographic patterning in an air environment.

  2. Dry etching of ferroelectric Bi4-xEuxTi3O12 (BET) thin films

    International Nuclear Information System (INIS)

    Lim, Kyu-Tae; Kim, Kyoung-Tae; Kim, Dong-Pyo; Kim, Chang-Il

    2004-01-01

    Bi 4-x Eu x Ti 3 O 12 (BET) thin films were etched by using a inductively coupled Cl 2 /Ar plasma. We obtained a maximum etch rate of 69 nm/min at a gas mixing ratio of Cl 2 (20 %)/Ar (80 %). This result suggests that an effective method for BET etching is chemically assisted physical etching. With increasing coil RF power, the plasma density increases so that the increased reactive free radicals and ions enhance the etch rates of BET, Pt, and SiO 2 . As the dc-bias voltage is increased, the increased ion energy leads to an increased etch rate of BET films. From X-ray photoelectron spectroscopy, the intensities of the Bi-O, the Eu-O, and the Ti-O peaks change with increasing Cl 2 concentration. For a pure Ar plasma, the peak associated with the oxygen-metal (O-M: TiO 2 , Bi 2 O 3 , Eu 2 O 3 ) bond seems to disappear while the pure oxygen peak does not appear. After the BET thin films is etched by using a Cl 2 /Ar plasma, the peak associated with the O-M bond increases slowly, but more quickly than the peak associated with pure oxygen atoms, due to a decrease in the Ar-ion bombardment. These results seem to indicate that Bi and Eu react little with Cl atoms and are removed predominantly by argon-ion bombardment. Also, Ti reacts little with Cl radicals and is mainly removed by chemically assisted physical etching.

  3. Improved photovoltaic performance from inorganic perovskite oxide thin films with mixed crystal phases

    Science.gov (United States)

    Chakrabartty, Joyprokash; Harnagea, Catalin; Celikin, Mert; Rosei, Federico; Nechache, Riad

    2018-05-01

    Inorganic ferroelectric perovskites are attracting attention for the realization of highly stable photovoltaic cells with large open-circuit voltages. However, the power conversion efficiencies of devices have been limited so far. Here, we report a power conversion efficiency of 4.20% under 1 sun illumination from Bi-Mn-O composite thin films with mixed BiMnO3 and BiMn2O5 crystal phases. We show that the photocurrent density and photovoltage mainly develop across grain boundaries and interfaces rather than within the grains. We also experimentally demonstrate that the open-circuit voltage and short-circuit photocurrent measured in the films are tunable by varying the electrical resistance of the device, which in turn is controlled by externally applying voltage pulses. The exploitation of multifunctional properties of composite oxides provides an alternative route towards achieving highly stable, high-efficiency photovoltaic solar energy conversion.

  4. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    KAUST Repository

    Lu, Chengliang; Dong, Shuai; Xia, Zhengcai; Luo, Hui; Yan, Zhibo; Wang, Haowen; Tian, Zhaoming; Yuan, Songliu; Wu, Tao; Liu, Junming

    2013-01-01

    magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ?800% upon a field of 2 Tesla at 2 K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement

  5. Strain profile and polarization enhancement in Ba0.5Sr0.5TiO3 thin films

    International Nuclear Information System (INIS)

    Amir, F.Z.; Donner, W.; Aspelmeyer, M.; Noheda, B.; Xi, X.X.; Moss, S.C.

    2012-01-01

    The sensitivity of spontaneous polarization to epitaxial strain for both 10 and 50 nm thick Ba 0.5 Sr 0.5 TiO 3 (BSTO) ferroelectric thin films has been studied. Crystal truncation rod (CTR) profiles in the 00L directions at different wavelengths, and grazing incidence diffraction (GID) in the 0K0 direction on a single crystal have been recorded. Modeling of the CTR data gives a detailed picture of the strain and provides clear evidence of the film out-of-plane expansion at the surface, an increase of the polarization, as well as a contraction at the interface. GID data confirm the fitting of the CTR, showing an in-plane expansion of the BSTO film at the interface and a contraction at the surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Thickness dependence of electrical properties in (0 0 1) oriented lead zirconate titanate films by laser ablation

    International Nuclear Information System (INIS)

    Zhu, T.J.; Lu, L.; Lai, M.O.; Soh, A.K.

    2007-01-01

    Highly (0 0 1)-oriented Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films with LaNiO 3 (LNO) bottom electrodes have been fabricated on amorphous TiN buffered Si substrates by pulsed laser deposition. The polarization-electric field (P-E) hysteresis of the deposited PZT films with different thickness ranging from 25 to 850 nm was measured. Results showed that the coercive field increases with the film thickness scaling down. No P-E loops could be obtained for the film of thickness of 25 nm. The deterioration of ferroelectric property in the thinnest film was attributed to extrinsic effect other than intrinsic size effect. Current-voltage (I-V) characteristics measurement showed the increase in leakage current of the PZT films with the decrease in the thickness of the films under the same bias voltage. At a high field regime, the leakage current of the PZT films of 25 nm thickness remained unchanged with increasing applied voltage. A totally depleted back-to-back Shottky barrier model was used to explain the effect of electrode interfaces on leakage current in the PZT films. It is believed that ferroelectric/electrode interfaces play an important role in the electrical properties of ferroelectric thin films with thickness at nanometer level

  7. Characterizations of photoconductivity of graphene oxide thin films

    Directory of Open Access Journals (Sweden)

    Shiang-Kuo Chang-Jian

    2012-06-01

    Full Text Available Characterizations of photoresponse of a graphene oxide (GO thin film to a near infrared laser light were studied. Results showed the photocurrent in the GO thin film was cathodic, always flowing in an opposite direction to the initial current generated by the preset bias voltage that shows a fundamental discrepancy from the photocurrent in the reduced graphene oxide thin film. Light illumination on the GO thin film thus results in more free electrons that offset the initial current. By examining GO thin films reduced at different temperatures, the critical temperature for reversing the photocurrent from cathodic to anodic was found around 187°C. The dynamic photoresponse for the GO thin film was further characterized through the response time constants within the laser on and off durations, denoted as τon and τoff, respectively. τon for the GO thin film was comparable to the other carbon-based thin films such as carbon nanotubes and graphenes. τoff was, however, much larger than that of the other's. This discrepancy was attributable to the retardation of exciton recombination rate thanks to the existing oxygen functional groups and defects in the GO thin films.

  8. Depth resolved lattice-charge coupling in epitaxial BiFeO3 thin film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeon Jun; Lee, Sung Su; Kwak, Jeong Hun; Kim, Young-Min; Jeong, Hu Young; Borisevich, Albina Y.; Lee, Su Yong; Noh, Do Young; Kwon, Owoong; Kim, Yunseok; Jo, Ji Young

    2016-12-01

    For epitaxial films, a critical thickness (tc) can create a phenomenological interface between a strained bottom layer and a relaxed top layer. Here, we present an experimental report of how the tc in BiFeO3 thin films acts as a boundary to determine the crystalline phase, ferroelectricity, and piezoelectricity in 60 nm thick BiFeO3/SrRuO3/SrTiO3 substrate. We found larger Fe cation displacement of the relaxed layer than that of strained layer. In the time-resolved X-ray microdiffraction analyses, the piezoelectric response of the BiFeO3 film was resolved into a strained layer with an extremely low piezoelectric coefficient of 2.4 pm/V and a relaxed layer with a piezoelectric coefficient of 32 pm/V. The difference in the Fe displacements between the strained and relaxed layers is in good agreement with the differences in the piezoelectric coefficient due to the electromechanical coupling.

  9. Effect of deposition temperature & oxygen pressure on mechanical properties of (0.5) BZT-(0.5)BCT ceramic thin films

    Science.gov (United States)

    Sailaja, P.; Kumar, N. Pavan; Rajalakshmi, R.; Kumar, R. Arockia; Ponpandian, N.; Prabahar, K.; Srinivas, A.

    2018-05-01

    Lead free ferroelectric thin films of {(0.5) BZT-(0.5) BCT} (termed as BCZT) were deposited on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition at four deposition temperatures 600, 650, 700, 750°C and at two oxygen pressures viz. 75mtorr and 100 mtorr using BCZT ceramic target (prepared by solid state sintering method). The effect of deposition temperature and oxygen pressure on the structure, microstructure and mechanical properties of BCZT films were studied. X-ray diffraction patterns of deposited films confirm tetragonal crystal symmetry and the crystallinity of the films increases with increasing deposition temperature. Variation in BCZT grain growth was observed when the films are deposited at different temperatures andoxygen pressures respectively. The mechanical properties viz. hardness and elastic modulus were also found to be high with increase in the deposition temperature and oxygen pressure. The results will be discussed.

  10. Lanthanum titanium perovskite compound: Thin film deposition and high frequency dielectric characterization

    Energy Technology Data Exchange (ETDEWEB)

    Le Paven, C., E-mail: claire.lepaven@univ-rennes1.fr [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Lu, Y. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Nguyen, H.V. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); CEA LETI, Minatec Campus, 38054 Grenoble (France); Benzerga, R.; Le Gendre, L. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Rioual, S. [Laboratoire de Magnétisme de Brest (EA CNRS 4522), Université de Bretagne Occidentale, 29000 Brest (France); Benzegoutta, D. [Institut des Nanosciences de Paris (INSP, UMR CNRS 7588), Université Pierre et Marie Curie, 75005 Paris (France); Tessier, F.; Cheviré, F. [Institut des Sciences Chimiques de Rennes (ISCR, UMR-CNRS 6226), Equipe Verres et Céramiques, Université de Rennes 1, 35000 Rennes (France); and others

    2014-02-28

    Perovskite lanthanum titanium oxide thin films were deposited on (001) MgO, (001) LaAlO{sub 3} and Pt(111)/TiO{sub 2}/SiO{sub 2}/(001)Si substrates by RF magnetron sputtering, using a La{sub 2}Ti{sub 2}O{sub 7} homemade target sputtered under oxygen reactive plasma. The films deposited at 800 °C display a crystalline growth different than those reported on monoclinic ferroelectric La{sub 2}Ti{sub 2}O{sub 7} films. X-ray photoelectron spectroscopy analysis shows the presence of titanium as Ti{sup 4+} ions, with no trace of Ti{sup 3+}, and provides a La/Ti ratio of 1.02. The depositions being performed from a La{sub 2}Ti{sub 2}O{sub 7} target under oxygen rich plasma, the same composition (La{sub 2}Ti{sub 2}O{sub 7}) is proposed for the deposited films, with an unusual orthorhombic cell and Cmc2{sub 1} space group. The films have a textured growth on MgO and Pt/Si substrates, and are epitaxially grown on LaAlO{sub 3} substrate. The dielectric characterization displays stable values of the dielectric constant and of the losses in the frequency range [0.1–20] GHz. No variation of the dielectric constant has been observed when a DC electric field up to 250 kV/cm was applied, which does not match a classical ferroelectric behavior at high frequencies and room temperature for the proposed La{sub 2}Ti{sub 2}O{sub 7} orthorhombic phase. At 10 GHz and room temperature, the dielectric constant of the obtained La{sub 2}Ti{sub 2}O{sub 7} films is ε ∼ 60 and the losses are low (tanδ < 0.02). - Highlights: • Lanthanum titanium oxide films were deposited by reactive magnetron sputtering. • A La{sub 2}Ti{sub 2}O{sub 7} chemical composition is proposed, with an unusual orthorhombic cell. • At 10 GHz, the dielectric losses are lower than 0.02. • No variation of the dielectric constant is observed under DC electric biasing.

  11. Development of neutron diffuse scattering analysis code by thin film and multilayer film

    International Nuclear Information System (INIS)

    Soyama, Kazuhiko

    2004-01-01

    To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering by thin film, roughness of surface of thin film, correlation function, neutron propagation by thin film, diffuse scattering by DWBA theory, measurement model, SDIFFF (neutron diffuse scattering analysis program by thin film) and simulation results are explained. On neutron diffuse scattering by multilayer film, roughness of multilayer film, principle of diffuse scattering, measurement method and simulation examples by MDIFF (neutron diffuse scattering analysis program by multilayer film) are explained. (S.Y.)To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering

  12. Thin film tritium dosimetry

    Science.gov (United States)

    Moran, Paul R.

    1976-01-01

    The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

  13. Poly (vinylidene fluoride-trifluoroethylene/barium titanate nanocomposite for ferroelectric nonvolatile memory devices

    Directory of Open Access Journals (Sweden)

    Uvais Valiyaneerilakkal

    2013-04-01

    Full Text Available The effect of barium titanate (BaTiO3 nanoparticles (particle size <100nm on the ferroelectric properties of poly (vinylidenefluoride-trifluoroethylene P(VDF-TrFE copolymer has been studied. Different concentrations of nanoparticles were added to P(VDF-TrFE using probe sonication, and uniform thin films were made. Polarisation - Electric field (P-E hysteresis analysis shows an increase in remnant polarization (Pr and decrease in coercive voltage (Vc. Piezo-response force microscopy analysis shows the switching capability of the polymer composite. The topography and surface roughness was studied using atomic force microscopy. It has been observed that this nanocomposite can be used for the fabrication of non-volatile ferroelectric memory devices.

  14. Surface topography and crystal and domain structures of films of ferroelectric copolymer of vinylidene difluoride and trifluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Kochervinskii, V. V., E-mail: kochval@mail.ru [Karpov Institute of Physical Chemistry, Branch (Russian Federation); Kiselev, D. A.; Malinkovich, M. D. [National University of Science and Technology MISiS (Russian Federation); Korlyukov, A. A.; Lokshin, B. V. [Russian Academy of Sciences, Nesmeyanov Institute of Organoelement Compounds (Russian Federation); Volkov, V. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Kirakosyan, G. A. [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation); Pavlov, A. S. [Karpov Institute of Physical Chemistry, Branch (Russian Federation)

    2017-03-15

    The crystallization of a copolymer from a solution at room temperature is found to lead to the formation of a metastable structure, characterized by the coexistence of ferroelectric and paraelectric phases. The fraction of the latter decreases after annealing above the Curie point. Atomic force microscopy (AFM) has revealed a difference in the surface topographies between the films contacting with air and the films contacting with a glass substrate. The microstructure of copolymer chains has been investigated by {sup 19}F NMR spectroscopy. The chain fragments with “defect” attached monomeric units are ejected to the surface. The character of the ferroelectric domains formed during crystallization and their size distribution are analyzed.

  15. Experimental evidence of enhanced ferroelectricity in Ca doped BiFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Costa, L.V.; Deus, R.C. [Universidade Estadual Paulista, UNESP, Faculdade de Engenharia de Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Portal das Colinas, CEP 12516-410 Guaratinguetá, SP (Brazil); Foschini, C.R.; Longo, E. [Universidade Estadual Paulista, UNESP, Faculdade de Engenharia de Bauru, Dept. de Eng. Mecânica, Av. Eng. Luiz Edmundo C. Coube 14-01, 17033-360 Bauru, SP (Brazil); Cilense, M. [Universidade Estadual Paulista, UNESP, Instituto de Química – Laboratório Interdisciplinar em Cerâmica (LIEC), Rua Professor Francisco Degni s/n, 14800-90 Araraquara, SP (Brazil); Simões, A.Z., E-mail: alezipo@yahoo.com [Universidade Estadual Paulista, UNESP, Faculdade de Engenharia de Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Portal das Colinas, CEP 12516-410 Guaratinguetá, SP (Brazil)

    2014-04-01

    Calcium (Ca)-doped bismuth ferrite (BiFeO{sub 3}) thin films prepared by using the polymeric precursor method (PPM) were characterized by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), polarization and piezoelectric measurements. Structural studies by XRD and TEM reveal the co-existence of distorted rhombohedral and tetragonal phases in the highest doped BiFeO{sub 3} where enhanced ferroelectric and piezoelectric properties are produced by internal strain. Resistive switching is observed in BFO and Ca-doped BFO which are affected by the barrier contact and work function of multiferroic materials and Pt electrodes. A high coercive field in the hysteresis loop is observed for the BiFeO{sub 3} film. Piezoelectric properties are improved in the highest Ca-doped sample due to changes in the crystal structure of BFO for a primitive cubic perovskite lattice with four-fold symmetry and a large tetragonal distortion within the crystal domain. This observation introduces magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom which are already present in the multiferroic BiFeO{sub 3}. - Highlights: • Ca doped BiFeO{sub 3} thin films were obtained by the polymeric precursor method. • Co-existence of distorted rhombohedral and tetragonal phases are evident. • Enhanced ferroelectric and piezoelectric properties are produced by the internal strain in the Ca doped BiFeO{sub 3} film.

  16. Thin films for emerging applications v.16

    CERN Document Server

    Francombe, Maurice H

    1992-01-01

    Following in the long-standing tradition of excellence established by this serial, this volume provides a focused look at contemporary applications. High Tc superconducting thin films are discussed in terms of ion beam and sputtering deposition, vacuum evaporation, laser ablation, MOCVD, and other deposition processes in addition to their ultimate applications. Detailed treatment is also given to permanent magnet thin films, lateral diffusion and electromigration in metallic thin films, and fracture and cracking phenomena in thin films adhering to high-elongation substrates.

  17. Interfaces and thin films physics

    International Nuclear Information System (INIS)

    Equer, B.

    1988-01-01

    The 1988 progress report of the Interfaces and Thin Film Physics laboratory (Polytechnic School France) is presented. The research program is focused on the thin films and on the interfaces of the amorphous semiconductor materials: silicon and silicon germanium, silicon-carbon and silicon-nitrogen alloys. In particular, the following topics are discussed: the basic processes and the kinetics of the reactive gas deposition, the amorphous materials manufacturing, the physico-chemical characterization of thin films and interfaces and the electron transport in amorphous semiconductors. The construction and optimization of experimental devices, as well as the activities concerning instrumentation, are also described [fr

  18. Buckling of Thin Films in Nano-Scale

    Directory of Open Access Journals (Sweden)

    Li L.A.

    2010-06-01

    Full Text Available Investigation of thin film buckling is important for life prediction of MEMS device which are damaged mainly by the delamination and buckling of thin films. In this paper the mechanical and thermal properties of compressed thin film titanium films with 150 nm thickness deposited on an organic glass substrate under mechanical and thermal loads were measured and characterized. In order to simulate the thin films which subjected to compound loads and the buckle modes the external uniaxial compression and thermal loading were subjected to the specimen by the symmetric loading device and the electrical film in this experiment. The temperature of the thin film deposited on substrate was measured using thermoelectric couple. The range of temperature accords with the temperature range of the MEMS. It is found that the size and number of the delamination and buckling of the film are depended upon the pre-fixed mechanical loading and thermal temperature. The thermal transient conduction and thermal stability of the film and substrate was studied with finite element method.

  19. Operating method of amorphous thin film semiconductor element

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Koshiro; Ono, Masaharu; Hanabusa, Akira; Osawa, Michio; Arita, Takashi

    1988-05-31

    The existing technologies concerning amorphous thin film semiconductor elements are the technologies concerning the formation of either a thin film transistor or an amorphous Si solar cell on a substrate. In order to drive a thin film transistor for electronic equipment control by the output power of an amorphous Si solar cell, it has been obliged to drive the transistor weth an amorphous solar cell which was formed on a substrate different from that for the transistor. Accordingly, the space for the amorphous solar cell, which was formed on the different substrate, was additionally needed on the substrate for the thin film transistor. In order to solve the above problem, this invention proposes an operating method of an amorphous thin film semiconductor element that after forming an amorphous Si solar cell through lamination on the insulation coating film which covers the thin film transistor formed on the substrate, the thin film transistor is driven by the output power of this solar cell. The invention eliminates the above superfluous space and reduces the size of the amorphous thin film semiconductor element including the electric source. (3 figs)

  20. Temperature dependence of LRE-HRE-TM thin films

    Science.gov (United States)

    Li, Zuoyi; Cheng, Xiaomin; Lin, Gengqi; Li, Zhen; Huang, Zhixin; Jin, Fang; Wang, Xianran; Yang, Xiaofei

    2003-04-01

    Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

  1. Tunability of resonance frequencies in a superconducting microwave resonator by using SrTiO sub 3 ferroelectric films

    CERN Document Server

    Sok, J; Lee, E H

    1998-01-01

    An applied dc voltage varies the dielectric constant of ferroelectric SrTiO sub 3 films. A tuning mechanism for superconducting microwave resonators was realized by using the variation in the dielectric constant of SrTiO sub 3 films. In order to estimate the values of the capacitance, C, and the loss tangent, tan delta, of SrTiO sub 3 ferroelectric capacitors, we used high-temperature superconducting microwave resonators which were composed of two ports, two poles, and dc bias circuits at the zero-field points. SrTiO sub 3 ferroelectric capacitors successfully controlled the resonant frequency of the resonator. Resonant frequencies of 3.98 GHz and 4.20 GHz were measured at bias voltages of 0 V and 50 V which correspond to capacitance values of 0.94 pF and 0.7pF, respectively. The values of the loss tangent, tan delta sub e sub f sub f , obtained in this measurements, were about 0.01.

  2. RF magnetron sputtered La3+-modified PZT thin films: Perovskite phase stabilization and properties

    International Nuclear Information System (INIS)

    Singh, Ravindra; Goel, T.C.; Chandra, Sudhir

    2008-01-01

    In this work, we report the preparation of lanthanum-modified lead zirconate titanate (PLZT) thin films in pure perovskite phase by RF magnetron sputtering. Various deposition parameters such as target-to-substrate spacing, sputtering gas composition, deposition temperature, post-deposition annealing temperature and time have been optimized to obtain PLZT films in pure perovskite phase. The films prepared in pure argon at 100 W RF power without external substrate heating exhibit pure perovskite phase after rapid thermal annealing (RTA) at 700 deg. C for 5 min. The film prepared at 225 deg. C substrate temperature also exhibits pure perovskite phase after RTA at 700 deg. C for 2 min. SIMS depth profile performed on one of the pure perovskite films (RTA at 700 deg. C for 5 min) shows very good stoichiometric uniformity of all elements of PLZT. The surface morphology of the films was examined using SEM and AFM. The dielectric, ferroelectric and electrical properties of the pure perovskite films were also investigated in detail. The remanent polarization for the films annealed at 700 deg. C for 5 and 2 min were found to be 15 and 13.5 μC cm -2 , respectively. Both the films have high DC resistivity of the order of 10 11 Ω cm at the electric field of ∼80 kV cm -1

  3. Application-related properties of giant magnetostrictive thin films

    International Nuclear Information System (INIS)

    Lim, S.H.; Kim, H.J.; Na, S.M.; Suh, S.J.

    2002-01-01

    In an effort to facilitate the utilization of giant magnetostrictive thin films in microdevices, application-related properties of these thin films, which include induced anisotropy, residual stress and corrosion properties, are investigated. A large induced anisotropy with an energy of 6x10 4 J/m 3 is formed in field-sputtered amorphous Sm-Fe-B thin films, resulting in a large magnetostriction anisotropy. Two components of residual stress, intrinsic compressive stress and tensile stress due to the difference of the thermal expansion coefficients between the substrate and thin film, are identified. The variation of residual stress with fabrication parameter and annealing temperature, and its influence on mechanical bending and magnetic properties are examined. Better corrosion properties are observed in Sm-Fe thin films than in Tb-Fe. Corrosion properties of Tb-Fe thin films, however, are much improved with the introduction of nitrogen to the thin films without deteriorating magnetostrictive properties

  4. Self-polarized PZT thin films:deposition, characterization and application

    Czech Academy of Sciences Publication Activity Database

    Suchanek, G.; Sandner, T.; Deyneka, Alexander; Gerlach, G.; Jastrabík, Lubomír

    2004-01-01

    Roč. 298, - (2004), s. 309-316 ISSN 0015-0193 R&D Projects: GA ČR GP202/02/D078 Keywords : ferroelectric film * self-polarization * presence detector Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.517, year: 2004

  5. Preparation of LiMn2O4 cathode thin films for thin film lithium secondary batteries by a mist CVD process

    International Nuclear Information System (INIS)

    Tadanaga, Kiyoharu; Yamaguchi, Akihiro; Sakuda, Atsushi; Hayashi, Akitoshi; Tatsumisago, Masahiro; Duran, Alicia; Aparacio, Mario

    2014-01-01

    Highlights: • LiMn 2 O 4 thin films were prepared by using the mist CVD process. • An aqueous solution of lithium and manganese acetates is used for the precursor solution. • The cell with the LiMn 2 O 4 thin films exhibited a capacity of about 80 mAh/g. • The cell showed good cycling performance during 10 cycles. - Abstract: LiMn 2 O 4 cathode thin films for thin film lithium secondary batteries were prepared by using so-called the “mist CVD process”, employing an aqueous solution of lithium acetate and manganese acetate, as the source of Li and Mn, respectively. The aqueous solution of starting materials was ultrasonically atomized to form mist particles, and mists were transferred by nitrogen gas to silica glass substrate to form thin films. FE-SEM observation revealed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 750 nm were obtained. The electrochemical cell with the thin films obtained by sintering at 700 °C exhibited a capacity of about 80 mAh/g, and the cell showed good cycling performance during 10 cycles

  6. P-type CuxS thin films: Integration in a thin film transistor structure

    International Nuclear Information System (INIS)

    Nunes de Carvalho, C.; Parreira, P.; Lavareda, G.; Brogueira, P.; Amaral, A.

    2013-01-01

    Cu x S thin films, 80 nm thick, are deposited by vacuum thermal evaporation of sulfur-rich powder mixture, Cu 2 S:S (50:50 wt.%) with no intentional heating of the substrate. The process of deposition occurs at very low deposition rates (0.1–0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of Cu x S films surface properties (morphology/roughness) under post deposition mild annealing in air at 270 °C and their integration in a thin film transistor (TFT) are the main objectives of this study. Accordingly, Scanning Electron Microscopy studies show Cu x S films with different surface morphologies, depending on the post deposition annealing conditions. For the shortest annealing time, the Cu x S films look to be constructed of grains with large dimension at the surface (approximately 100 nm) and consequently, irregular shape. For the longest annealing time, films with a fine-grained surface are found, with some randomly distributed large particles bound to this fine-grained surface. Atomic Force Microscopy results indicate an increase of the root-mean-square roughness of Cu x S surface with annealing time, from 13.6 up to 37.4 nm, for 255 and 345 s, respectively. The preliminary integration of Cu x S films in a TFT bottom-gate type structure allowed the study of the feasibility and compatibility of this material with the remaining stages of a TFT fabrication as well as the determination of the p-type characteristic of the Cu x S material. - Highlights: • Surface properties of annealed Cu x S films. • Variation of conductivity with annealing temperatures of Cu x S films. • Application of evaporated Cu x S films in a thin film transistor (TFT) structure. • Determination of Cu x S p-type characteristic from TFT behaviour

  7. Novel ferroelectric capacitor for non-volatile memory storage and biomedical tactile sensor applications

    International Nuclear Information System (INIS)

    Liu, Shi Yang; Chua, Lynn; Tan, Kian Chuan; Valavan, S.E.

    2010-01-01

    We report on novel ferroelectric thin film compositions for use in non-volatile memory storage and biomedical tactile sensor applications. The lead zirconate titanate (PZT) composition was modified by lanthanum (La 3+ ) (PLZT) and vanadium (V 5+ ) (PZTV, PLZTV) doping. Hybrid films with PZTV and PLZTV as top layers are also made using seed layers of differing compositions using sol-gel and spin coating methods. La 3+ doping decreased the coercive field, polarization and leakage current, while increasing the relative permittivity. V 5+ doping, while having similar effects, results in an enhanced polarization, with comparable dielectric loss characteristics. Complex doping of both La 3+ and V 5+ in PLZTV, while reducing the polarization relative to PZTV, significantly decreases the coercive field. Hybrid films have a greater uniformity of grain formation than non-hybrid films, thus decreasing the coercive field, leakage current and polarization fatigue while increasing the relative permittivity. Analysis using X-ray diffraction (XRD) verified the retention of the PZT perovskite structure in the novel films. PLZT/PZTV has been identified as an optimal ferroelectric film composition due to its desirable ferroelectric, fatigue and dielectric properties, including the highest observed remnant polarization (P r ) of ∼ 25 μC/cm 2 , saturation polarization (P sat ) of ∼ 58 μC/cm 2 and low coercive field (E c ) of ∼ 60 kV/cm at an applied field of ∼ 1000 kV/cm, as well as a low leakage current density of ∼ 10 -5 A/cm 2 at 500 kV/cm and fatigue resistance of up to ∼ 10 10 switching cycles.

  8. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2014-06-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  9. Thin liquid films dewetting and polymer flow

    CERN Document Server

    Blossey, Ralf

    2012-01-01

    This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films haven proven to be an invaluable experimental model system.   What is it that makes thin film instabilities special and interesting, warranting a whole book? There are several answers to this. Firstly, thin polymeric films have an important range of applications, and with the increase in the number of technologies available to produce and to study them, this range is likely to expand. An understanding of their instabilities is therefore of practical relevance for the design of such films.   Secondly, thin liquid films are an interdisciplinary research topic. Interdisciplinary research is surely not an end to itself, but in this case it leads to a fairly heterogeneous community of theoretical and experimental physicists, engineers, physical chemists, mathematicians and others working on the...

  10. Self-assembly of dodecaphenyl POSS thin films

    Science.gov (United States)

    Handke, Bartosz; Klita, Łukasz; Niemiec, Wiktor

    2017-12-01

    The self-assembly abilities of Dodecaphenyl Polyhedral Oligomeric Silsesquioxane thin films on Si(1 0 0) surfaces were studied. Due to their thermal properties - relatively low sublimation temperature and preservation of molecular structure - cage type silsesquioxanes are ideal material for the preparation of a thin films by Physical Vapor Deposition. The Ultra-High Vacuum environment and the deposition precision of the PVD method enable the study of early stages of thin film growth and its molecular organization. X-ray Reflectivity and Atomic Force Microscopy measurements allow to pursuit size-effects in the structure of thin films with thickness ranges from less than a single molecular layer up to several tens of layers. Thermal treatment of the thin films triggered phase change: from a poorly ordered polycrystalline film into a well-ordered multilayer structure. Self-assembly of the layers is the effect of the π-stacking of phenyl rings, which force molecules to arrange in a superlattice, forming stacks of alternating organic-inorganic layers.

  11. Organic thin films and surfaces directions for the nineties

    CERN Document Server

    Ulman, Abraham

    1995-01-01

    Physics of Thin Films has been one of the longest running continuing series in thin film science consisting of 20 volumes since 1963. The series contains some of the highest quality studies of the properties ofvarious thin films materials and systems.In order to be able to reflect the development of todays science and to cover all modern aspects of thin films, the series, beginning with Volume 20, will move beyond the basic physics of thin films. It will address the most important aspects of both inorganic and organic thin films, in both their theoretical as well as technological aspects. Ther

  12. Effects of annealing schedule on orientation of Bi3.2Nd0.8Ti3O12 ferroelectric film prepared by chemical solution deposition process

    International Nuclear Information System (INIS)

    He, H.Y.; Huang, J.F.; Cao, L.Y.; Wang, L.S.

    2006-01-01

    Fatigue-free Bi 3.2 Nd 0.8 Ti 3 O 12 ferroelectric thin films were successfully prepared on p-Si(1 1 1) substrate using chemical solution deposition process. The orientation and formation of thin film under different annealing schedules were studied. XRD analysis indicated that (2 0 0)-oriented films with degree of orientation of I (200) /I (117) = 2.097 and 0.466 were obtained by preannealing for 10 min at 400 deg. C followed by rapid thermal annealing for 3, 10 and 20 min at 700 deg. C, respectively (0 0 8)-oriented films with degree of orientation of I (008) /I (117) = 1.706 were obtained by rapid thermal annealing for 3 min at 700 deg. C without preannealing, and (0 0 8)-oriented films with degree of orientation of I (008) /I (117) = 0.719 were obtained by preheating the film from room temperature at 20 deg. C/min followed by annealing for 10 min at 700 deg. C. The a-axis and c-axis orientation decreased as increase of annealing time due to effects of (1 1 1)-oriented substrate. AFM analysis further indicated that preannealing at 400 deg. C for 10 min followed by rapid thermal annealing for 3 min at 700 deg. C resulted in formation of platelike crystallite parallel to substrate surface, however rapid thermal annealing for 3 min at 700 deg. C without preannealing resulted in columnar crystallite perpendicular to substrate surface

  13. Novel chemical analysis for thin films

    International Nuclear Information System (INIS)

    Usui, Toshio; Kamei, Masayuki; Aoki, Yuji; Morishita, Tadataka; Tanaka, Shoji

    1991-01-01

    Scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) was applied for fluorescence X-ray analysis of 50A- and 125A-thick Au thin films on Si(100). The intensity of the AuM line (2.15 keV) emitted from the Au thin films varied as a function of the take-off angle (θ t ) with respect to the film surface; the intensity of AuM line from the 125A-thick Au thin film was 1.5 times as large as that of SiK α line (1.74 keV) emitted from the Si substrate when θ t = 0deg-3deg, in the vicinity of a critical angle for total external reflection of the AuM line at Si (0.81deg). In addition, the intensity of the AuM line emitted from the 50A-thick Au thin film was also sufficiently strong for chemical analysis. (author)

  14. Effects of annealing temperature on the structures, ferroelectric and magnetic properties of Aurivillius Bi5Ti3FeO15 polycrystalline films

    International Nuclear Information System (INIS)

    Bai, W.; Zhu, J.Y.; Wang, J.L.; Lin, T.; Yang, J.; Meng, X.J.; Tang, X.D.; Zhu, Z.Q.; Chu, J.H

    2012-01-01

    The effects of annealing temperature on the structures, ferroelectric and magnetic properties of Aurivillius layer-structured Bi 5 Ti 3 FeO 15 (BTF) films were investigated. It was found that an annealing temperature above 625 °C can lead to the appearance of Bi 4 Ti 3 O 12 (BiT) secondary phase on Pt substrates. The reduction of the grain sizes was simultaneously confirmed by X-ray diffraction and atomic force microscopy with the introduction of the BiT phase. Moreover, the remanent polarization and coercive field of the BTF films were dramatically enhanced with the introduction of the BiT phase. Improved ferromagnetism for the BTF films was demonstrated upon increasing annealing temperature. Our data indicated that the ferroelectricity strongly correlated with the growth orientation of the BTF films. Finally, the possible factors for the obvious increase of the remanent polarization and coercive field, and the possible reasons for the enhanced ferromagnetic properties were discussed with increasing annealing temperature. - Highlights: ► Effects of annealing temperature on physical properties of BTF films were studied. ► Improved multiferroic properties were shown with annealing temperature. ► Ferroelectricity strongly depended on the growth orientation of the BTF films. ► Possible factors were proposed to explain the improved multiferroic properties.

  15. Nanostructured thin film coatings with different strengthening effects

    Directory of Open Access Journals (Sweden)

    Panfilov Yury

    2017-01-01

    Full Text Available A number of articles on strengthening thin film coatings were analyzed and a lot of unusual strengthening effects, such as super high hardness and plasticity simultaneously, ultra low friction coefficient, high wear-resistance, curve rigidity increasing of drills with small diameter, associated with process formation of nanostructured coatings by the different thin film deposition methods were detected. Vacuum coater with RF magnetron sputtering system and ion-beam source and arc evaporator for nanostructured thin film coating manufacture are represented. Diamond Like Carbon and MoS2 thin film coatings, Ti, Al, Nb, Cr, nitride, carbide, and carbo-nitride thin film materials are described as strengthening coatings.

  16. Thin Film Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K.

    1998-11-19

    The motivation to develop thin film technologies dates back to the inception of photovoltaics. It is an idea based on achieving truly low-cost photovoltaics appropriate for mass production and energy significant markets. The key to the idea is the use of pennies worth of active materials. Since sunlight carries relatively little energy in comparison with combustion-based energy sources, photovoltaic (PV) modules must be cheap to produce energy that can be competitive. Thin films are presumed to be the answer to that low-cost requirement. But how cheap do they have to be? The following is an oversimplified analysis that allows some insight into this question.

  17. Thin films: Past, present, future

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K

    1995-04-01

    This report describes the characteristics of the thin film photovoltaic modules necessary for an acceptable rate of return for rural areas and underdeveloped countries. The topics of the paper include a development of goals of cost and performance for an acceptable PV system, a review of current technologies for meeting these goals, issues and opportunities in thin film technologies.

  18. Non-linear optics of nano-scale pentacene thin film

    Science.gov (United States)

    Yahia, I. S.; Alfaify, S.; Jilani, Asim; Abdel-wahab, M. Sh.; Al-Ghamdi, Attieh A.; Abutalib, M. M.; Al-Bassam, A.; El-Naggar, A. M.

    2016-07-01

    We have found the new ways to investigate the linear/non-linear optical properties of nanostructure pentacene thin film deposited by thermal evaporation technique. Pentacene is the key material in organic semiconductor technology. The existence of nano-structured thin film was confirmed by atomic force microscopy and X-ray diffraction. The wavelength-dependent transmittance and reflectance were calculated to observe the optical behavior of the pentacene thin film. It has been observed the anomalous dispersion at wavelength λ 800. The non-linear refractive index of the deposited films was investigated. The linear optical susceptibility of pentacene thin film was calculated, and we observed the non-linear optical susceptibility of pentacene thin film at about 6 × 10-13 esu. The advantage of this work is to use of spectroscopic method to calculate the liner and non-liner optical response of pentacene thin films rather than expensive Z-scan. The calculated optical behavior of the pentacene thin films could be used in the organic thin films base advanced optoelectronic devices such as telecommunications devices.

  19. Oxidation of ruthenium thin films using atomic oxygen

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, A.P.; Bogan, J.; Brady, A.; Hughes, G.

    2015-12-31

    In this study, the use of atomic oxygen to oxidise ruthenium thin films is assessed. Atomic layer deposited (ALD) ruthenium thin films (~ 3 nm) were exposed to varying amounts of atomic oxygen and the results were compared to the impact of exposures to molecular oxygen. X-ray photoelectron spectroscopy studies reveal substantial oxidation of metallic ruthenium films to RuO{sub 2} at exposures as low as ~ 10{sup 2} L at 575 K when atomic oxygen was used. Higher exposures of molecular oxygen resulted in no metal oxidation highlighting the benefits of using atomic oxygen to form RuO{sub 2}. Additionally, the partial oxidation of these ruthenium films occurred at temperatures as low as 293 K (room temperature) in an atomic oxygen environment. - Highlights: • X-ray photoelectron spectroscopy study of the oxidation of Ru thin films • Oxidation of Ru thin films using atomic oxygen • Comparison between atomic oxygen and molecular oxygen treatments on Ru thin films • Fully oxidised RuO{sub 2} thin films formed with low exposures to atomic oxygen.

  20. Thin Films in the Photovoltaic Industry

    International Nuclear Information System (INIS)

    Jaeger-Waldau, A.

    2008-03-01

    In the past years, the yearly world market growth rate for Photovoltaics was an average of more than 40%, which makes it one of the fastest growing industries at present. Business analysts predict the market volume to increase to 40 billion euros in 2010 and expect rising profit margins and lower prices for consumers at the same time. Today PV is still dominated by wafer based Crystalline Silicon Technology as the 'working horse' in the global market, but thin films are gaining market shares. For 2007 around 12% are expected. The current silicon shortage and high demand has kept prices higher than anticipated from the learning curve experience and has widened the windows of opportunities for thin film solar modules. Current production capacity estimates for thin films vary between 3 and 6 GW in 2010, representing a 20% market share for these technologies. Despite the higher growth rates for thin film technologies compared with the industry average, Thin Film Photovoltaic Technologies are still facing a number of challenges to maintain this growth and increase market shares. The four main topics which were discussed during the workshop were: Potential for cost reduction; Standardization; Recycling; Performance over the lifetime.

  1. Nanostructured thin films and coatings functional properties

    CERN Document Server

    Zhang, Sam

    2010-01-01

    The second volume in ""The Handbook of Nanostructured Thin Films and Coatings"" set, this book focuses on functional properties, including optical, electronic, and electrical properties, as well as related devices and applications. It explores the large-scale fabrication of functional thin films with nanoarchitecture via chemical routes, the fabrication and characterization of SiC nanostructured/nanocomposite films, and low-dimensional nanocomposite fabrication and applications. The book also presents the properties of sol-gel-derived nanostructured thin films as well as silicon nanocrystals e

  2. Holistic RBS-PIXE data reanalysis of SBT thin film samples

    International Nuclear Information System (INIS)

    Reis, M.A.; Barradas, N.P.; Pascual-Izarra, C.; Chaves, P.C.; Ramos, A.R.; Alves, E.; Gonzalez-Aguilar, G.; Costa, M.E.V.; Miranda Salvado, I.M.

    2007-01-01

    The growth of SrBi 2 Ta 2 O 9 (SBT) films on top of Pt electrode substrates is an important issue for the fabrication of ferroelectric based memories. In a recent publication, SBT thin films grown using seeded and unseeded procedures were studied by PIXE and RBS. Difficulties and misfits found in the comparison of results from both techniques were, at that time, overcome by physical considerations. These, although not rendering interpretation impossible, left out the possibility of understanding the exact nature of the differences between the interface behavior in each case. In the present work it is shown that the reanalysis of the same data using the recently developed RBS-PIXE simultaneous and self-consistent calculation present in NDF leads to stronger conclusions on the solid state reaction occurring during the deposition stage for both types of samples. Allowing for the occurrence of solid state reactions between the deposited film and the Pt electrode even in the case of seeded samples leads to a full explanation of IBA data, this result showing that in complex systems such as this, the PIXE data are essential and must be integrated with the RBS data in an holistic analysis, in order to properly unfold the depth profile of the samples. Contrary to what is usually supposed PIXE data is therefore shown to contain hidden depth structure information

  3. Intrinsically conductive polymer thin film piezoresistors

    DEFF Research Database (Denmark)

    Lillemose, Michael; Spieser, Martin; Christiansen, N.O.

    2008-01-01

    We report on the piezoresistive effect in the intrinsically conductive polymer, polyaniline. A process recipe for indirect patterning of thin film polyaniline has been developed. Using a specially designed chip, the polyaniline thin films have been characterised with respect to resistivity...

  4. Direct imprinting of indium-tin-oxide precursor gel and simultaneous formation of channel and source/drain in thin-film transistor

    Science.gov (United States)

    Haga, Ken-ichi; Kamiya, Yuusuke; Tokumitsu, Eisuke

    2018-02-01

    We report on a new fabrication process for thin-film transistors (TFTs) with a new structure and a new operation principle. In this process, both the channel and electrode (source/drain) are formed simultaneously, using the same oxide material, using a single nano-rheology printing (n-RP) process, without any conventional lithography process. N-RP is a direct thermal imprint technique and deforms oxide precursor gel. To reduce the source/drain resistance, the material common to the channel and electrode is conductive indium-tin-oxide (ITO). The gate insulator is made of a ferroelectric material, whose high charge density can deplete the channel of the thin ITO film, which realizes the proposed operation principle. First, we have examined the n-RP conditions required for the channel and source/drain patterning, and found that the patterning properties are strongly affected by the cooling rate before separating the mold. Second, we have fabricated the TFTs as proposed and confirmed their TFT operation.

  5. Modification of energy band alignment and electric properties of Pt/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}/Pt thin-film ferroelectric varactors by Ag impurities at interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, S.; Komissinskiy, P., E-mail: komissinskiy@oxide.tu-darmstadt.de; Flege, S.; Li, S.; Rachut, K.; Klein, A.; Alff, L. [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2014-06-28

    We report on the effects of Ag impurities at interfaces of parallel-plate Pt/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}/Pt thin film ferroelectric varactors. Ag impurities occur at the interfaces due to diffusion of Ag from colloidal silver paint used to attach the varactor samples with their back side to the plate heated at 600–750 °C during deposition of Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}. X-ray photoelectron spectroscopy and secondary ion mass spectrometry suggest that amount and distribution of Ag adsorbed at the interfaces depend strongly on the adsorbent surface layer. In particular, Ag preferentially accumulates on top of the Pt bottom electrode. The presence of Ag significantly reduces the barrier height between Pt and Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} leading to an increased leakage current density and, thus, to a severe degradation of the varactor performance.

  6. Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3-(K0.5Na0.5)0.4(Sr 0.6Ba0.4)0.8Nb2O6 thin films

    KAUST Repository

    Yao, Yingbang; Mak, C. L.

    2014-01-01

    were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis

  7. Thermal conductivity model for nanoporous thin films

    Science.gov (United States)

    Huang, Congliang; Zhao, Xinpeng; Regner, Keith; Yang, Ronggui

    2018-03-01

    Nanoporous thin films have attracted great interest because of their extremely low thermal conductivity and potential applications in thin thermal insulators and thermoelectrics. Although there are some numerical and experimental studies about the thermal conductivity of nanoporous thin films, a simplified model is still needed to provide a straightforward prediction. In this paper, by including the phonon scattering lifetimes due to film thickness boundary scattering, nanopore scattering and the frequency-dependent intrinsic phonon-phonon scattering, a fitting-parameter-free model based on the kinetic theory of phonon transport is developed to predict both the in-plane and the cross-plane thermal conductivities of nanoporous thin films. With input parameters such as the lattice constants, thermal conductivity, and the group velocity of acoustic phonons of bulk silicon, our model shows a good agreement with available experimental and numerical results of nanoporous silicon thin films. It illustrates that the size effect of film thickness boundary scattering not only depends on the film thickness but also on the size of nanopores, and a larger nanopore leads to a stronger size effect of the film thickness. Our model also reveals that there are different optimal structures for getting the lowest in-plane and cross-plane thermal conductivities.

  8. Magneto-optic properties and optical parameter of thin MnCo films

    Directory of Open Access Journals (Sweden)

    E Attaran Kakhki

    2009-09-01

    Full Text Available Having precise hysterics loop of thin ferroelectric and ferromagnetic layers for optical switching and optical storages are important. A hysterieses loop can be achieved from a phenomenon call the magneto-optic effect. The magneto-optic effect is the rotation of a linear polarized electromagnetic wave propagated through a ferromagnetic medium. When light is transmitted through a layer of magnetic material the result is called the Faraday effects and in the reflection mode Kerr effect. In the present work we prepared a thin layer of MnxCo3-xO4 (0≤ x ≤ 1 and a binary form of MnO/Co3O4 by the spray pyrolysis method. The films have been characterized by a special set up of magneto-optic hysterics loop plotter containing a polarized He- Ne laser beam and a special electronic circuit. Faraday rotation were measured for these films by hysterics loop plotter and their optical properties were also obtained by spatial software designed for this purpose according to Swane Poel theoretical method. The measurements show that the samples at diluted Mn study has are ferromagnetic and the magneto-optic rotation show a good enhance respect to the single Co layers. Also, the study has shown that the MnCo oxide layer have two different energy gaps and by increasing of Mn this energy decreases and fall to 0.13 eV.

  9. Photoinduced hydrophobic surface of graphene oxide thin films

    International Nuclear Information System (INIS)

    Zhang Xiaoyan; Song Peng; Cui Xiaoli

    2012-01-01

    Graphene oxide (GO) thin films were deposited on transparent conducting oxide substrates and glass slides by spin coating method at room temperature. The wettability of GO thin films before and after ultraviolet (UV) irradiation was characterized with water contact angles, which increased from 27.3° to 57.6° after 3 h of irradiation, indicating a photo-induced hydrophobic surface. The UV–vis absorption spectra, Raman spectroscopy, X-ray photoelectron spectroscopy, and conductivity measurements of GO films before and after UV irradiation were taken to study the mechanism of photoinduced hydrophobic surface of GO thin films. It is demonstrated that the photoinduced hydrophobic surface is ascribed to the elimination of oxygen-containing functional groups on GO molecules. This work provides a simple strategy to control the wettability properties of GO thin films by UV irradiation. - Highlights: ► Photoinduced hydrophobic surface of graphene oxide thin films has been demonstrated. ► Elimination of oxygen-containing functional groups in graphene oxide achieved by UV irradiation. ► We provide novel strategy to control surface wettability of GO thin films by UV irradiation.

  10. Optical thin film deposition

    International Nuclear Information System (INIS)

    Macleod, H.A.

    1979-01-01

    The potential usefulness in the production of optical thin-film coatings of some of the processes for thin film deposition which can be classified under the heading of ion-assisted techniques is examined. Thermal evaporation is the process which is virtually universally used for this purpose and which has been developed to a stage where performance is in almost all respects high. Areas where further improvements would be of value, and the possibility that ion-assisted deposition might lead to such improvements, are discussed. (author)

  11. Optical thin films and coatings from materials to applications

    CERN Document Server

    Flory, Francois

    2013-01-01

    Optical coatings, including mirrors, anti-reflection coatings, beam splitters, and filters, are an integral part of most modern optical systems. This book provides an overview of thin film materials, the properties, design and manufacture of optical coatings and their use across a variety of application areas.$bOptical coatings, including mirrors, anti-reflection coatings, beam splitters, and filters, are an integral part of most modern optical systems. Optical thin films and coatings provides an overview of thin film materials, the properties, design and manufacture of optical coatings and their use across a variety of application areas. Part one explores the design and manufacture of optical coatings. Part two highlights unconventional features of optical thin films including scattering properties of random structures in thin films, optical properties of thin film materials at short wavelengths, thermal properties and colour effects. Part three focusses on novel materials for optical thin films and coatings...

  12. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-01-12

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force.

  13. Sputtering materials for VLSI and thin film devices

    CERN Document Server

    Sarkar, Jaydeep

    2010-01-01

    An important resource for students, engineers and researchers working in the area of thin film deposition using physical vapor deposition (e.g. sputtering) for semiconductor, liquid crystal displays, high density recording media and photovoltaic device (e.g. thin film solar cell) manufacturing. This book also reviews microelectronics industry topics such as history of inventions and technology trends, recent developments in sputtering technologies, manufacturing steps that require sputtering of thin films, the properties of thin films and the role of sputtering target performance on overall p

  14. Influence of Zr/Ti ratio and preferred orientation on polarization switching and domain configuration of Pb(Zr1-xTix)O3 thin films

    International Nuclear Information System (INIS)

    Lee, Young Hyun; Lee, Jung Kun; Hong, Kug Sun

    2003-01-01

    The (100) and (111) oriented Pb(Zr 1-x Ti x )O 3 (PZT) thins films were prepared on Pt/TiO 2 /SiO 2 /Si(100) substrate using sol-gel process. The ferroelectric and dielectric properties were evaluated as a function of Zr/Ti ratio and the origin of their changes were discussed in terms of domain engineering. With increasing Zr/Ti ratio, the remnant polarization of the polar axis decreased from 23.87 to 10.66 μC/cm 2 and the difference of the saturated polarization between polar axis and non-polar axis increased systematically. The fatigue rate of PZT films was disproportional to Zr/Ti ratio. At a composition of x = 0.7, the remnant polarization decreased from 2P r = 30.82 μC/cm 2 to 26.60 μC/cm 2 after 6.9 x 10 10 cycles. The fatigue rate was also related to the direction of polarization reversal and the increased fatigue behavior was observed in polar axis. These results were discussed with the aid of the domain configuration and the switching current, which revealed the role of the internal stress on ferroelectric property of PZT films

  15. Theoretical study of the multiferroic properties in M-doped (M=Co, Cr, Mg) ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bahoosh, S.G. [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Apostolov, A.T. [University of Architecture, Civil Engineering and Geodesy, Faculty of Hydrotechnics, Department of Physics, 1, Hristo Smirnenski Blvd., 1046 Sofia (Bulgaria); Apostolova, I.N. [University of Forestry, Faculty of Forest Industry, 10, Kl. Ohridsky Blvd., 1756 Sofia (Bulgaria); Trimper, S. [Institute of Physics, Martin-Luther-University, D-06099 Halle (Germany); Wesselinowa, Julia M. [University of Sofia, Department of Physics, Blvd. J. Bouchier 5, 1164 Sofia (Bulgaria)

    2015-01-01

    The origin of multiferroism is still an open problem in ZnO. We propose a microscopic model to clarify the occurrence of multiferroism in this material. Using Green's function technique we study the influence of ion doping and size effects on the magnetization and polarization of ZnO thin films. The calculations for magnetic Co- and Cr-ions are based on the s–d model, the transverse Ising model in terms of pseudo-spins and a biquadratic magnetoelectric coupling, whereas in case of nonmagnetic Mg-ions the model takes into account the Coulomb interaction and an indirect coupling between the pseudo-spins via the conduction electrons. We show that the magnetization M exhibits a maximum for a fixed concentration of the doping ions. Furthermore M increases with decreasing film thickness N. The polarization increases with increasing concentration of the dopant and decreasing N. The results are in good agreement with the experimental data. - Highlights: • The paper analyzes the multiferroic properties of doped ZnO thin films by a microscopic model. • The magnetization exhibits a maximum at a fixed doping concentration. • The polarization increases with growing dopant concentration. • The ferroelectric transition temperature is enhanced for increasing dopant concentration.