Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session A33: Focus Session: Dielectric, Ferroelectric, and Piezoelectric Oxides: Piezoelectrics, Oxides on Semiconductors, and Applications |
Hide Abstracts |
Sponsoring Units: DMP DCOMP Chair: Valentino Cooper, Oak Ridge National Laboratory Room: C143/149 |
Monday, March 21, 2011 8:00AM - 8:12AM |
A33.00001: High-Throughput Density Functional Theory Categorization of Ferroelectric Ternary Perovskite Oxides for Use as High-Performance Piezoelectrics Rickard Armiento, Boris Kozinsky, Marco Fornari, Gerbrand Ceder We present a nearly exhaustive density functional theory (DFT) survey over the chemical space of perovskite compounds on ABO3 form, with the aim of identifying alloy end points for new piezoelectric materials. Our screening criteria on the DFT results selects 85 relevant compounds, among which all well known alloy end points for high performance piezoelectrics are present. We analyze the compounds with respect to macroscopic polarization, born effective charges, and energy differences between different structure distortions. We discuss the energy features that cause the high piezoelectric performance of the well known piezoelectric lead zirconate titanate (PZT), and to what extent these features are rare among the found compounds. The results are used to discuss relevant isovalent alloys of the selected compounds. [Preview Abstract] |
Monday, March 21, 2011 8:12AM - 8:24AM |
A33.00002: Searching for ferroelectricity and piezoelectricity in Heusler compounds using first-principles calculations Anindya Roy, Joseph Bennett, Karin M. Rabe, David Vanderbilt Hundreds of half Heusler (HH) and full Heusler (FH) compounds have been synthesized, and they exhibit a multitude of properties. However, we are unaware of any Heusler compounds showing ferroelectricity (FE), or for which the piezoelectricity (PzE) has been measured. Determining these polar properties would be of theoretical interest as well as having practical importance for the design of new functional materials. In this {\it ab initio} study, we search a large set of HH and FH compounds, both known and hypothetical, for FE/PzE. We screen the zone-center phonons, computed with first-principles density-functional-theory methods, for unstable polar modes that would drive a distortion to a ferroelectric phase, and calculate PzE coefficients of compounds in the $F\bar{4}3m$ space group, which includes all HH and many FH, using density-functional perturbation theory. Preliminary results from our calculations confirm that the Heusler compounds are very robust against FE instabilities. However, we found several HH compounds having $e_{14}$ coefficients in the range of 0.5-1.0 C/m$^2$, comparable to that of some well-known piezoelectric materials such as ZnO. We also investigate the effects of epitaxial constraints on these properties, both for bulk materials and for superlattices built of Heusler materials. [Preview Abstract] |
Monday, March 21, 2011 8:24AM - 8:36AM |
A33.00003: Origin of the anomalous piezoelectric response in wurtzite Sc$_{x}$Al$_{1-x}$N alloys Ferenc Tasnadi, Bjorn Alling, Carina Hoglund, Gunilla Wingqvist, Jens Birch, Lars Hultman, Igor A. Abrikosov We present the theory that reveals the origin of the observed anomalous enhancement of piezoelectric response in wurtzite Sc$_{x}$Al$_{1-x}$N alloys [1]. Our first-principles calculations confirm that the 400{\%} increase of the piezoelectric constant is an intrinsic alloying effect. The energy surface topology is found to be strongly influenced by the alloying, being elongated around the global minimum along c=a direction. This leads to the large elastic softening along the crystal parameter c, and raises significantly the intrinsic sensitivity to axial strain resulting in the highly increased piezoelectric constant. The effect is particularly accentuated at intermediate compositions where the elongated double-minimum energy landscape is flattened due to the energy proximity of the wurtzite and so far experimentally unknown hexagonal phases of these alloys. Our observation provides a route for the design of materials with high piezoelectric response. \\[4pt] [1] F. Tasnadi, \textit{et al., }Phys. Rev. Lett. \textbf{104}, 137601 (2010). [Preview Abstract] |
Monday, March 21, 2011 8:36AM - 9:12AM |
A33.00004: Giant piezoelectricity on Si for hyper-active MEMS Invited Speaker: Smart materials that can sense, manipulate, and position are crucial to the functionality of micro- and nano-machines. Integration of single crystal piezoelectric films on silicon offers the opportunity of high performance piezoelectric microelectromechanical systems (MEMS) incorporating all the advantages of large scale integration on silicon substrates with on-board electronic circuits, improving performance and eliminating common failure points associated with heterogeneous integration. We have fabricated oxide heterostructures with the highest piezoelectric coefficients and figure of merit for piezoelectric energy harvesting system ever realized on silicon substrates by synthesizing epitaxial thin films of Pb(Mg$_{1/3}$Nb$_{2/3})$O$_{3}$-PbTiO$_{3}$(PMN-PT) on vicinal (001) Si wafers using an epitaxial (001) SrTiO$_{3}$ template layer. We have also demonstrated fabrication of PMN-PT cantilevers, whose mechanical behavior is consistent with theoretical calculations using the material constants of a bulk PMN-PT single crystal. These epitaxial heterostructures with giant piezoelectricity can be used for MEMS or NEMS devices that function with low drive voltage such as transducers for ultrasound medical imaging, micro-fluidic control and energy harvesting. Beyond electromechanical devices, our approach will open a new avenue to tune and modulate the properties of other multifunctional materials by dynamic strain control. This work was done in collaboration with S. H. Baek, J. Park, D. M. Kim, V. Aksyuk, R. R. Das, S. D. Bu, D. A. Felker, J. Lettieri, V. Vaithyanathan, S. S. N. Bharadwaja, N. Bassiri-Gharb, Y. B. Chen, H. P. Sun, H. W. Jang, D. J. Kreft, S. K. Streiffer, R. Ramesh, X. Q. Pan, S. Trolier-McKinstry, D. G. Schlom, M. S. Rzchowski, R. Blick. This work was supported by the National Science Foundation through grants ECCS-0708759. [Preview Abstract] |
Monday, March 21, 2011 9:12AM - 9:24AM |
A33.00005: Monolayer modification of interface dipoles between a-Al$_{2}$O$_{3}$ and silicon Stephanie Fernandez-Pe\~{n}a, A.M. Kolpak, S. Ismail-Beigi, C.H. Ahn, F.J. Walker Interface dipoles occurring at high-k oxide-silicon interfaces play an important role in the function of electronic devices. The magnitude and sign of the dipole depend sensitively on the chemistry of the first few atomic planes around the interface. In this work, we control the dipole between a-Al$_{2}$O$_{3}$ and silicon by monolayer modifications of interface chemistry. The interface composition ranges from a clean 2$\times$1 Si (001) surface prepared by SiO desorption in ultra high vacuum to surfaces having thicknesses of SiO$_{x}$ as thin as 1 monolayer. In these materials, we observe using x-ray photoelectron spectroscopy band-offset changes induced by a modified interface dipole as large as 0.4 eV. From the capacitance-voltage behavior of metal oxide semiconductor (MOS) devices, we find that this dipole responds to an applied electric field in a non-linear way. We understand this non- linear behavior using first principles theory of complex oxide- electrode interfaces. [Preview Abstract] |
Monday, March 21, 2011 9:24AM - 9:36AM |
A33.00006: Alloyed Hf-La High-k Oxide Film Grown by Remote Plasma Atomic Layer Deposition Fu Tang, Chiyu Zhu, Robert Nemanich The growth of alloyed Hf-La oxide was investigated using remote plasma atomic layer deposition (RPALD) at low temperatures ranging from 80 to 250C. The low temperature process is particularly important for the applications in thin film transistors, where the device is very often fabricated on flexible plastic substrate. Alloyed oxide films were deposited with 1-3 cycles of La oxide between two adjacent Hf oxide cycles. The atomic bonding structure was determined by in situ XPS. AFM and TEM were used to characterize the morphology and crystalline structure. The XPS results indicated that the percentages of Hf and La components in the alloyed films can be controlled by the ratio of the number of Hf and La cycles. In addition, carbon residue in the alloyed film is reduced compared with that of a pure La oxide film. This is attributed to the role of Hf in preventing formation of La carbonate. The AFM and TEM images indicated that the periodic alloying has suppressed the crystallization of HfO2 and led to improvement of the morphology compared with the roughness of the pure Hf oxide film. The IV curves show that the alloyed Hf-La oxide film has a break down voltage of 3 MV/cm. [Preview Abstract] |
Monday, March 21, 2011 9:36AM - 9:48AM |
A33.00007: Linking the Electronic and Atomic Structure of Epitaxial Complex Oxides on Semiconductors Divine Kumah, James Reiner, Joseph Ngai, Yaron Segal, Alexie Kolpak, Diana Qiu, Sohrab Ismail-Beigi, Charles Ahn, Fred Walker, Dong Su, Yi Zhu, Zhan Zhang Understanding the interfacial coupling between materials with different electronic properties is critical to achieve the integration of epitaxial complex oxides with semiconductors. Using a combination of synchrotron x-ray diffraction and first principles calculations, we show that the electronic properties and atomic structure of epitaxial SrTiO$_{3}$ films on Si, and BaTiO$_{3}$ films on Ge are directly linked to the chemical composition at their respective interfaces. Sub-angstrom [001] cation-anion displacements observed in the SrTiO$_{3}$/Si system, lead to a positively polarized film. The polar distortions are found to arise from an interplay between compressive strain and localized interface states. In contrast to SrTiO$_{3}$/Si, we find that the BaTiO$_{3}$/Ge interface has a 2x1 structure that drives an in-plane polarization. [Preview Abstract] |
Monday, March 21, 2011 9:48AM - 10:00AM |
A33.00008: Piezoelectric force microscopy of crystalline oxide-semiconductor heterostructures Matthew S.J. Marshall, James W. Reiner, Divine Kumah, Peter Maksymovych, Art P. Baddorf, Charles Ahn, Fred J. Walker Coupling the properties of a ferroelectric material to a semiconductor has been pursued for decades. Epitaxial, coherently strained thin films of ferroelectric BaTiO3 can be grown on germanium with out-of-plane polarization using molecular beam epitaxy (MBE). Similarly, epitaxial thin films of SrTiO3 can be grown on Si with some indication that these films can be ferroelectric. In this work, we use oxide MBE to grow epitaxial films of SrTiO3 and BaTiO3 on Si and Ge, respectively, and we use both ambient and ultrahigh vacuum (UHV) piezoelectric force microscopy (PFM) to study the question of ferroelectricity in these systems. We find that the modulation of the PFM amplitude for thin films of SrTiO3 (6 uc. and 25 uc) on Si is the result of an electrostatic mechanism that can be traced back to tip-induced or as-grown defects in the film. These results are compared to results on thin films of BaTiO3 on Ge. [Preview Abstract] |
Monday, March 21, 2011 10:00AM - 10:12AM |
A33.00009: Molecular Beam Epitaxy of YInO3 on GaN Cameron Keenan, Felio Perez, David Lederman Novel non-volatile ferroelectric materials are of significant interest in the field of materials science as devices and integrated circuits approach smaller dimensions and broader use. Materials and device structures incorporating GaN are also of particular interest as devices transition away from relying solely on silicon. Oxide materials, such as YMnO3 on GaN, have been researched in an effort to fill this niche, but problems associated with lattice mismatch and interfacial degradation have limited sample quality and utility. YInO3 is another material that may provide an avenue for oxide device integration with GaN. YInO3 thin films were prepared on metal organic chemical vapor deposition GaN templates via molecular beam epitaxy. Atomic force microscopy was used to determine surface roughness and morphology. X-ray reflectivity and x-ray diffraction were implemented in order to determine the thickness, crystallinity, and crystal structure of the films. Results for structural analysis, as well as, ferroelectric measurements will be presented and discussed. [Preview Abstract] |
Monday, March 21, 2011 10:12AM - 10:24AM |
A33.00010: Electrocaloric and Pyroelectric Properties of Ferroelectric Films Jialan Zhang, George Rossetti, Pamir Alpay We use a non-linear thermodynamic model to investigate the electrocaloric and pyroelectric response of thin film perovskite ferroelectrics under the influence of differing electrical, thermal and mechanical boundary conditions including bias and driving field, temperature, lateral clamping, and misfit strain. A comparison of ferroelectric solid solutions comprised of BaTiO$_{3}$, PbTiO$_{3}$ and/or SrTiO$_{3}$ illustrates the influence of composition and lateral clamping effect on the electrocaloric properties. The theoretical analysis of a variety of ferroelectric thin films on IC-friendly substrates such as Si and sapphire shows that the room temperature dielectric and electrothermal responses of these films depend strongly on the synthesis/processing temperature$.$ These combined results provide insights concerning how the deposition temperature, substrate material and composition can be adjusted to obtain desired electrothermal properties. [Preview Abstract] |
Monday, March 21, 2011 10:24AM - 10:36AM |
A33.00011: Polarization switching in Ferroelectric capacitors Asif Khan, Ramamoorthy Ramesh, Salahuddin Sayeef A capacitor is an electrical circuit element that stores energy in the form of electric field. A ferroelectric is essentially analogous to an ordinary capacitor with an electrically switchable built-in polarization. The properties of ferroelectrics had been well described by Landau's phenomenological framework. However, during polarization switching in realistic ferroelectrics, switching occurs via ``non-ideal'' defect mediated domain nucleation and domain wall movement. It can be argued that, within the framework of nucleation based models of FE switching, energy injected into the FE is not stored in the form of electric field, which makes capacitor like description of FE during switching ``unclear.'' In this talk, we will revisit the different switching based models of ferroelectrics and discus the properties of FE as a circuit element during switching. [Preview Abstract] |
Monday, March 21, 2011 10:36AM - 10:48AM |
A33.00012: Synthesis and characterization of novel high energy density capacitors for green energy Venkata S. Puli, Ashok Kumar, Ram S. Katiyar We have developed lead free high energy density capacitor materials, {\{}Ba(Zr$_{0.2}$Ti$_{0.8})$O$_{3}${\}}$_{(1-x)}$ {\{}(Ba$_{0.7}$Ca$_{0.3})$TiO$_{3}${\}}x [x = 0.10,0.15,0.20 (BZT$_{(1-x) }$BCT$_{x}$ ] with high dielectric constant and moderate breakdown voltage. The ceramic materials were prepared using high energy ball milling for 4 hours at 400 rpm. The ball milled powders were calcined at 1250$^{o}$C for 10hrs. Ceramic pellets having 13mm diameter were prepared using hydraulic press (2 ton) and sintered at 1400$^{o}$C-1500$^{o}$C for 4 hrs. X-ray diffraction studies of the sintered pellets revealed the rhombohedral/pseudo cubic crystal structure. The crystal structure was further confirmed by Raman spectra and TEM analysis. High dielectric constant and moderate polarization ($\sim $P$_{s}\sim $ 15-25 $\mu $C/cm$^{2})$ were obtained in the sintered pellets. The SEM images revealed monolithic grain growth in samples sintered at 1500$^{o}$C. Preliminary data show moderate breakdown field $\sim $ 15-20 kV/cm and energy density of 0.12-0.3 J/cm$^{3}$ for all compositions. Details of the results will be presented. [Preview Abstract] |
Monday, March 21, 2011 10:48AM - 11:00AM |
A33.00013: Capacitance response and strain sensing properties of barium titanate thin film Satreerat Hodak, Pavarit Promsena, Anurat Wisittsoraat, Jose Hodak Strain gauges are devices that convert mechanical stress into an electronic signal. In this research, barium titanate (BaTiO$_{3})$ films were deposited on flexible borosilicate glasses using a sol-gel method. Interdigitated electrodes were patterned on the films to fabricate a strain gauge. The strain gauge comprised of an array of individual coplanar capacitors on a 1.2x0.4 cm rectangular borosilicate glass of 0.16 mm thickness. A parallelogram clamp and a mechanically amplified piezoelectric actuator were used for supporting the device under test and for the application of the strain, respectively. Measurements of the strain were carried out on a cantilever beam by monitoring the changes in device capacitance and the frequency shift of an oscillator circuit. We obtained the frequency change per unit stress equal to 0.00163 MHz/MPa and the frequency change per unit strain equal to 1.038x10$^{-4}$ MHz/unit strain, respectively. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700