Resistive Switching

Daniele Ielmini is associate professor in the Department of Electrical Engineering, Information Science and Bioengineering, Politecnico di Milano, Italy. He obtained his Ph.D. in Nuclear Engineering from Politecnico di Milano in 2000. He held visiting positions at Intel and Stanford University in 2006. His research group investigates emerging device technologies, such as phase change memory (PCM) and resistive switching memory (ReRAM) for both memory and computing applications. He has authored six book chapters, more than 200 papers published in international journals and presented at international conferences, and four patents to his name. Professor Ielmini received the Intel Outstanding Research Award in 2013 and the ERC Consolidator Grant in 2014. Rainer Waser is professor at the faculty for Electrical Engineering and Information Technology at the RWTH Aachen University and director at the Peter Grunberg Institute at the Forschungszentrum Julich (FZJ), Germany. His research group is focused on fundamental aspects of electronic materials and on such integrated devices as nonvolatile memories, logic devices, sensors and actuators. Professor Waser has published about 500 technical papers. Since 2003, he has been the coordinator of the research program on nanoelectronic systems within the Germany national research centres in the Helmholtz Association. In 2007, he has been co-founder of the Julich-Aachen Research Alliance, section Fundamentals of Future Information Technology (JARA-FIT). In 2014, he was awarded the Gottfried Wilhelm Leibniz Prize of the Deutsche Forschungsgemeinschaft and the Tsungming Tu Award of the Ministry of Science and Technology of Taiwan.

Preface XIX List of Contributors XXI 1 Introduction to Nanoionic Elements for Information Technology 1 Rainer Waser, Daniele Ielmini, Hiro Akinaga, Hisashi Shima, H.-S. Philip Wong, Joshua J. Yang, and Simon Yu 1.1 Concept of Two-Terminal Memristive Elements 1 1.1.1 Classifications Based on Behavior, Mechanisms, and Operation Modes 1 1.1.2 Scope of the Book 6 1.1.3 History 9 1.2 Memory Applications 12 1.2.1 Performance Requirements and ParameterWindows 12 1.2.2 Device Isolation in Crossbar Arrays 16 1.2.3 3-D Technology 19 1.2.4 Memory Hierarchy 20 1.3 Logic Circuits 21 1.4 Prospects and Challenges 24 Acknowledgments 25 References 25 2 ReRAM Cells in the Framework of Two-Terminal Devices 31 E. Linn, M. Di Ventra, and Y. V. Pershin 2.1 Introduction 31 2.2 Two-Terminal Device Models 32 2.2.1 Lumped Elements 32 2.2.2 Ideal Circuit Element Approach 32 2.2.3 Dynamical Systems Approach 33 2.2.3.1 Memristive Systems 33 2.2.3.2 Memristor 34 2.2.4 Significance of the Initial Memristor and Memristive System Definitions in the Light of Physics 34 2.2.4.1 Limitations of Ideal Memristor Models 35 2.2.5 Memristive, Memcapacitive, and Meminductive Systems 35 2.2.6 ReRAM: Combination of Elements, Combination of Memory Features, and Consideration of Inherent Battery Effects 36 2.3 Fundamental Description of Electronic Devices with Memory 38 2.4 Device Engineer's View on ReRAM Devices as Two-Terminal Elements 40 2.4.1 Modeling of Electrochemical Metallization (ECM) Devices 41 2.4.2 Modeling of Valence Change Mechanism (VCM) Devices 43 2.5 Conclusions 46 Acknowledgment 47 References 47 3 Atomic and Electronic Structure of Oxides 49 Tobias Zacherle, Peter C. Schmidt, and Manfred Martin 3.1 Introduction 49 3.2 Crystal Structures 50 3.3 Electronic Structure 54 3.3.1 From Free Atoms to the Solid State 55 3.3.2 Electrons in Crystals 58 3.3.2.1 Free Electron Model (Sommerfeld Model) 58 3.3.2.2 Band Structure Model 60 3.3.2.3 Density of States (DOS) and Partial DOS 62 3.3.2.4 Crystal Field Splitting 64 3.3.2.5 Exchange and Correlation 65 3.3.2.6 Computational Details 66 3.4 Material Classes and Characterization of the Electronic States 67 3.4.1 Metals 67 3.4.2 Semiconductors 68 3.4.3 Insulators 71 3.4.4 Point Defect States 72 3.4.5 Surface States 73 3.4.6 Amorphous States 75 3.5 Electronic Structure of Selected Oxides 76 3.5.1 Nontransition Metal Oxides 76 3.5.1.1 Al2O3 76 3.5.1.2 SrO 77 3.5.1.3 ZnO 77 3.5.2 Titanates 79 3.5.2.1 TiO 79 3.5.2.2 Ti2O3 79 3.5.2.3 TiO2 81 3.5.2.4 SrTiO3 82 3.5.3 Magnetic Insulators 82 3.5.3.1 NiO 84 3.5.3.2 MnO 85 3.5.4 MVB Metal Oxides 86 3.5.4.1 Metal-Insulator Transitions: NbO2, VO2, and V2O3 86 3.5.4.2 Tantalum Oxides TaOx 87 3.6 Ellingham Diagram for Binary Oxides 90 Acknowledgments 91 References 91 4 Defect Structure of Metal Oxides 95 Giuliano Gregori 4.1 Definition of Defects 95 4.1.1 Zero-Dimensional Defects 95 4.1.2 One-Dimensional Defects 95 4.1.3 Two-Dimensional Defects 97 4.1.4 Three-Dimensional Defects 97 4.2 General Considerations on the EquilibriumThermodynamics of Point Defects 98 4.3 Definition of Point Defects 99 4.3.1 Intrinsic Defects 99 4.3.1.1 Frenkel Defects 99 4.3.1.2 Anti-Frenkel Defects 99 4.3.1.3 Schottky Defects 100 4.3.1.4 Anti-Schottky Defects 100 4.3.1.5 Electron Band-Band Transfer 100 4.3.2 Extrinsic Defects 100 4.3.2.1 Reactions with the Environment 100 4.3.2.2 The Brouwer Diagram 101 4.3.2.3 Impurities and Dopants 102 4.4 Space-Charge Effects 103 4.4.1 Mott-Schottky Situation 104 4.4.2 Gouy-Chapman Situation 105 4.5 Case Studies 106 4.5.1 Titanium Oxide (Rutile) 106 4.5.1.1 Nominally Pure TiO2 107 4.5.1.2 Acceptor-Doped TiO2 108 4.5.1.3 Donor-Doped TiO2 108 4.5.1.4 The Role of Dislocations 109 4.5.2 Strontium Titanate 110 4.5.2.1 Acceptor-Doped SrTiO3 110 4.5.2.2 Donor-Doped SrTiO3 111