NANOSCALE PHENOMENA FERROELECTRIC THIN FILMS NANOSCALEPHENOMENAIN FERROELECTRIC THIN FILMS edited by Seungbum Hong Samsung Advanced Institute ofTechnology, Korea SPRINGER-SCIENCE+BUSINESS MEDIA, LLC Library of Congress Cataloging-in-Publication Nanoscale phenomena in ferroelectric thin films 1 edited by Seungbum Hong. p.cm. Includes bibliographical references and index. ISBN 978-1-4020-7630-5 ISBN 978-1-4419-9044-0 (eBook) DOI 10.1007/978-1-4419-9044-0 1. Ferroelectric thin films. 2. Nanostructure materials. 1. Hong, Seungbum TA418.9.T45N35 2003 621.3815'2-dc22 Copyright ©2004 Springer Science+Business Media New York Originally published by Kluwer Academic Publishers in 2004 Softcover reprint of the hardcover 1 st edition 2004 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transrnitted in any form or by any means, electronic, mechanical, photo-copying, rnicrofilrning, recording, or otherwise, without the prior written perrnission ofthe publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Perrnissions for books published in the USA: [email protected] Perrnissions for books published in Europe: perrnissions @wkap.nl Printed on acid-free paper. Table of Contents ListofContributors ix Preface xi Acknowledgment xiv Part I.Electrical Characterization inNanoscale Ferroelectric Capacitor I. Testing and characterization offerroelectric thinfilm capacitors In Kyeong. Yoo 1. TestCircuits 3 2. HystereticProperty 5 3. Capacitance andCurrent. : 9 4. Stored Energy 9 5. Ageing 11 6. Fatigue 13 7. Imprint 14 8. Leakage Current 16 9. ElectricalDegradation 21 10.Breakdown 22 11.Pyroelectric Effect 26 12.Additional tests for commercial memory cells 29 References 37 II. Size effects in ferroelectric film capacitors: role of the film thickness and capacitorsize IgorStolichnov 1. Introduction 39 2. Size effects: role of the ferroelectric film thickness, impact of thepassive layer andlocalcharge injection .40 3. Size effects: role of the capacitor size and impact of nonhomogeneousstress 48 4. Conclusions and outlook 54 Acknowledgements 55 References 55 vi III.Ferroelectric thin films for memory applications: nanoscale characterization byscanning force microscopy Alexei Gruverman 1. Introduction 57 2. Experimental Approach 59 3. VariationsinFerroelectricPropertiesatthe nanoscale 65 4. PPM studies of retention behavior 74 5. Nanoscale Leakage Current Mapping 81 6. Conclusion 83 Acknowledgment 84 References 84 IV. Nanoscale domain dynamics inferroelectric thinfilms V.Nagarajan andR.Ramesh 1. Introduction 88 2. Thin Film MaterialsandCharacterization 89 3. PolarizationRelaxation atthe Nanoscale 92 4. Nanoscale Piezoelectric and Ferroelectric Behavior 97 5. Conclusions 106 Acknowledgements 107 References 108 V. Polarization switching and fatigue of ferroelectric thin films studied byPFM Seungbum Hong 1. Introduction 111 2. Polarization switching 114 3. Fatigue:suppression ofswitchable polarization 126 4. Summary and Conclusion 130 Acknowledgments 131 References 131 Vll Part II. Nano Domain Manipulation and Visualization in Ferroelectric Materials VI. Domainswitching andself-polarizationin perovskitethinfilms A. Roelofs, K. SzotandR. Waser 1. Introduction 135 2. PTO polycrystallinethin films onplatinized silicon wafers 136 3. PTO single grains 140 4. Epitaxial PZT thin films onSTO/LSCO 142 5. The origin of self-polarization 146 References 153 VII. Dynamic-contact electrostatic force microscopy and its application toferroelectric domain Z.G.Khim andJ.Hong 1. Introduction 157 2. DetectionMechanismofDC-EFM 160 3. Observation ofFerroelectric Domains 165 4. Control offerroelectric domains 174 5. Conclusion 179 Acknowledgements 181 References 181 VIIl Polarization and charge dynamics in ferroelectric materials with SPM S.Kalinin andD.A. Bonnell 1. Introduction 183 2. Principles of Non-contactElectrostaticSPMs 185 3. Domain Structure Reconstruction from SPM 186 4. Origins ofDomain Contrast in EFM and SSPM 189 5. Polarization and Charge Dynamics on the BaTi0 (100) 3 Surface 196 6. Screening and Thermodynamics of Adsorption on BaTi0 3 (100) Surfaces 204 7. Domain Selective Photochemical Activity on Ferroelectric Surfaces 209 8. Conclusions 214 V111 Acknowledgements 215 References 215 IX. Nanoscale investigation of MOCVD-Pb(Zr,Ti)03 thin films using scanningprobe microscopy HironoriFujisawa andMasaru Shimizu 1. Introduction 219 2. Experimentalprocedure 22() 3. Local Current Flowof PZTThin Films 222 4. Crystalline Structure and Ferroelectric Properties of Nanosized PZT Islands 225 5. Polarization SwitchingProcesses inEpitaxial PZTThin Films 228 6. Conclusions 234 Acknowledgements 235 References 235 X. SPM measurements offerroelectrics at MHz frequencies Bryan. D.Huey 1. Introduction 239 2. Sensitivity tocantilever Loading 240 3. Periodic excitation and detection 248 4. MHz measurement Techniques at theNanoscale 252 Acknowledgements 261 References 261 XI. Application of ferroelectric domains in nanometer scale for high density storagedevices HyunjungShin 1. Introduction 263 2. MEMS technology and Probe-based storage systems 265 3. FerroelectricDomain writing andreading innanometer scale 270 4. Research Issues and perspective of ferroelectric domains for storage applications 275 5. Summary andconclusions 276 Acknowledgments 276 References 277 List of Contributors Chapter 1 IN KYEONGYOO Samsung Fellow,SamsungAdvanced Institute ofTechnology,Suwon, Korea Chapter 2 IGOR STOLICHNOV Laboratory of Ceramics, Swiss Federal Institute of Technology, Lausanne, Switzerland Chapter 3 ALEXEI GRUVERMAN North Carolina State University, Raleigh,NC, U. S. Chapter 4 V.NAGARAJAN and R.RAMESH Materials Research Science and Engineering Center, Universityof Maryland, College Park,MD,U.S. Chapter 5 SEUNGBUM HONG Storage Laboratory, Samsung Advanced Institute of Technology, Suwon, Korea Chapter 6 A. ROELOFS,K. SZOTand R.WASER Center of Nanoelectronic Systems for Information Technology (CNI),IFF, Research CenterJulich,D-52425 Julich,Germany Chapter7 ZHEONG G. KHIM and JAEWAN HONG School of Physics and Nano-Science and Technology Interdisciplinary Program,Seoul National University, Seoul, Korea Chapter 8 SERGEIV.KALININ*and DAWNA. BONNELL Oak Ridge National Laboratory,Oak Ridge,TN,U. S. Universityof Pennsylvania, Philadelphia, PA,U. S. x Chapter9 HIRONORIFUJISAWAand MASARU SHIMIZU Department of Electrical Engineering and Computer Sciences, Himeji InstituteofTechnology, Hyogo, Japan Chapter 10 BRYAND.HUEY National Institute of Standards andTechnology, MD, U. S. Chapter 11 HYUNJUNGSHIN School of Advanced Materials Engineering, Kookmin University, Seoul, Korea Preface This book presents the recent advances in the field of nanoscale science and engineering of ferroelectric thin films. It comprises two main parts, i.e. electrical characterization in nanoscale ferroelectric capacitor, and nano domain manipulation and visualization in ferroelectric materials. Well known le'adingexperts both in relevant academia and industry over theworld (U.S., Japan, Germany, Switzerland, Korea) were invited to contribute to each chapter. The first part under the title of electrical characterization in nanoscale ferroelectric capacitors starts with Chapter 1, "Testing and characterization of ferroelectric thin film capacitors," written by Dr. I. K. Yoo. The author provides a comprehensive review on basic concepts and terminologies of ferroelectric properties and their testing methods. This chapter also covers reliability issues in FeRAMs that are crucial for commercialization of high density memory products. In Chapter 2, "Size effects in ferroelectric film capacitors: role ofthe film thickness and capacitorsize," Dr.I. Stolichnov discusses thesize effects both in in-plane and out-of-plane dimensions of the ferroelectric thin film. The author successfully relates the electric performance and domain dynamics with proposed models of charge injection and stress induced phase transition. The author's findings present both a challenging problem and the clue to its solution of reliably predicting the switching properties for ultra-thin ferroelectric capacitors. In Chapter 3, "Ferroelectric thin films for memory applications: nanoscale characterization by scanning force microscopy," Prof. A. Gruverman focuses on the reliability issues of ferroelectric thinfilms such as spatial variations of imprint or local hysteresisloops,which leads todifferent switching behaviors from capacitor to capacitor when the capacitor scales down to the size comparable to the grain size. The author discusses another important reliability issues of retention loss and dielectric breakdown, and provides a model of nucleation triggered by built-in field at film/electrode interface and growth enhanced by polarization-dependentspace charge field, which explains the stability enhancement of both positive and negative domains byselectingproper electrode materials. In Chapter 4, "Nanoscale dynamics in ferroelectric thin films," Dr. V. Nagarajan and Prof. R. Ramesh covers two seemingly independent but closely related topics of domain dynamics in model thin films and piezoelectric behavior in nanostructures. The authors have shown the important role of 90°domains and domain wall in time dependent relaxation of the remnant polarization and in gigantic piezoelectric strain at saturation