Resistive Switching: Oxide Materials, Mechanisms, Devices and Operations

Description

This book provides a broad examination of redox-based resistive switching memories (ReRAM), a promising technology for novel types of nanoelectronic devices, according to the International Technology Roadmap for Semiconductors, and the materials and physical processes used in these ionic transport-based switching devices. It covers defect kinetic models for switching, ReRAM deposition/fabrication methods, tuning thin film microstructures, and material/device characterization and modeling.  A slate of world-renowned authors address the influence of type of ionic carriers, their mobility, the role of the local and chemical composition and environment, and facilitate readers’ understanding of the effects of composition and structure at different length scales (e.g., crystalline vs amorphous phases, impact of extended defects such as dislocations and grain boundaries). ReRAMs show outstanding potential for scaling down to the atomic level, fast operation in the nanosecond range, low power consumption, and non-volatile storage.  The book is ideal for materials scientists and engineers concerned with novel types of nanoelectronic devices such as memories, memristors, and switches for logic and neuromorphic computing circuits beyond the von Neumann concept. Contents Preface References Memristive Computing Devices and Applications 1 Introduction 2 Memristive Devices Based on Redox Processes 2.1 Metal-Ion-Based Devices 2.2 Oxygen-Ion-Based Devices 3 Phase Change Devices 4 Memristive Device Applications: Classical Computing Systems 4.1 Memory and Storage 4.2 Digital Logic Circuitry 5 Applications in Emerging Computing Architectures 5.1 Neuromorphic Computing 5.2 Analog Computing 5.3 Stochastic Computing and Security Applications 6 Discussions 7 Conclusion References Resistive Random Access Memory (RRAM) Technology: From Material, Device, Selector, 3D Integration to Bottom-Up Fabrication 1 resistive Memories: OxRAM and CBRAM 2 Selector Candidates 2.1 General Requirements 2.2 Unipolar Selectors 2.3 Bipolar Selectors 2.4 Self-Selecting Cells 3 RRAM Switching Materials Engineering 3.1 Valence Change Mechanism (VCM) 3.1.1 Switching Layers 3.1.2 Electrode Material 3.1.3 Doping 3.2 Electrochemical Metallization 3.2.1 Metal Alloy 3.2.2 Buffer Layer Insertion 3.3 Non-Filamentary RRAM 4 RRAM Three-Dimensional (3D) Integration 5 Bottom-Up Fabrication of RRAM 6 Conclusion References Review of Mechanisms Proposed for Redox Based Resistive Switching Structures 1 Introduction 2 Electroforming 3 Filament 4 Bulk Reduction 5 Filament Electrode Contact 6 Variations in the Filament Length 7 Switching 8 Unipolar Switching 9 Memory 10 Necessary Condition for Memory 11 Hysteresis 12 I-V Curve Crossing 13 Low Current and Compliance Current 14 Electrodes 15 Effect of Humidity References Probing Electrochemistry at the Nanoscale: In Situ TEM and STM Characterizations of Conducting Filaments in Memristive Devices 1 In Situ TEM Characterization of Metal Filament-Based ReRAM 1.1 Sample Structures Enabling In Situ TEM Observations 1.2 Classification of Dynamic Metal Filament Growth Modes 1.2.1 Growth Mode a: High Ion Mobility, High Redox Rate Case 1.2.2 Growth Mode b: Low Ion Mobility, Low Redox Rate Case 1.2.3 Growth Mode c: Low Ion Mobility, High Redox Rate Case 1.2.4 Growth Mode d: High Ion Mobility, Low Redox Rate Case 2 In Situ TEM Observations of Individual Metal Clusters 3 In Situ TEM Observation of Cyclic Switching of ReRAM 3.1 SET/RESET Cycling in CBRAM 3.2 Multiple Switching Cycles 3.3 Device Characterization & Reliability Issues Analyzable by In Situ TEM 4 In-Situ TEM of Filamentary ReRAM Based on Oxides 5 Scanning Tunneling Microscopy for the Investigation of Resistance Switching Phenomena 6 Concluding Remarks References Nanoscale Characterization of Resistive Switching Using Advanced Conductive Atomic Force Microscopy –Based Setups 1 Introduction 2 RS Observation Using Standard CAFM 2.1 Tip-Induced RS 2.2 Device-Level RS Plus CAFM Read Scans 3 Filaments Observation in Three Dimensions by Scalpel SPM 3.1 Scalpel SPM and Data Acquisition 3.2 Filament Observation by Scalpel SPM 3.3 Scalpel SPM for Site-Specific and Failure Analysis 4 Pressure Modulated Conductance Microscopy 5 Conclusion References SiO2-Based Conductive-Bridging Random Access Memory 1 Introduction 2 Physicochemical Principles and Materials 2.1 Filament Growth in SiO2 CBRAM 2.2 Cation Conduction in SiO2 Thin Films 2.3 Electrochemical Reactions and the Role of Counter Charge 3 Device Characterization 3.1 Recent Advances and Challenges in In Situ Electron Microscopy 3.2 In Situ Spectroscopy 3.3 Impedance Spectroscopy 4 Device Performance 4.1 Technology Comparison 4.2 Multilevel Cell (MLC) Operation 4.3 Retention 4.4 Endurance 5 Circuits and Applications 5.1 Memory Arrays 5.2 Active Arrays 5.3 Passive Arrays 5.4 Neuromorphic Systems 5.5 Radiation-Tolerant Memory 6 Challenges and Perspectives 7 Conclusions References Reset Switching Statistics of TaOx-Based Memristor 1 Introduction 2 Experiments and Results 3 Conclusion References Effect of O2- Migration in Pt/HfO2/Ti/Pt Structure 1 Introduction 2 Process Development 2.1 Device Fabrication Methodology 2.2 Electrical Measurement Setup 3 Results and Discussion 3.1 Switching Mechanism and Post-fabrication Aging Effect 3.2 Effect of Ti Layer Thickness and Tuning of the Oxidation Rate 3.3 Introduction of an ALD-Deposited Oxygen Barrier Layer 4 Conclusion References Operating Mechanism and Resistive Switching Characteristics of Two- and Three-Terminal Atomic Switches Using a Thin Metal Oxide Layer 1 Introduction 2 Operating Mechanism of Two-Terminal Atomic Switches 3 Effect of Moisture Absorption in the Oxide Matrix 4 Development of Three-Terminal Atomic Switches 5 Conclusion Supplementary Information References Interface-Type Resistive Switching in Perovskite Materials 1 Introduction 2 Perovskites 2.1 Crystal Structure 2.2 Accommodation of Crystal Defects 2.3 Conduction Mechanisms 3 Perovskites Properties as a Playground for Resistive Switching 3.1 Mechanisms Contributing to Interface-Type Resistive Switching 3.1.1 Valence Change Mechanism 3.1.2 Electronic and Electrostatic Mechanisms 3.1.3 Ferroelectric Polarization Controlled Mechanisms 3.2 Studies of Conduction Mechanisms in Resistive Switching Perovskites 3.3 Memristive Devices Based on Perovskites 4 Material Aspects of Valence-Change Interface-Type Resistive Switching 4.1 Role of Doping 4.1.1 Role of Cation Doping 4.1.2 Role of Oxygen Stoichiometry 4.2 Role of Additional Layers (Multilayers) 4.3 Role of the Electrode 4.3.1 Work Function (WF) 4.3.2 Oxygen Affinity 4.4 Effect of the Atmosphere 5 Conclusions and Future Prospects References Volume Resistive Switching in Metallic Perovskite Oxides Driven by the Metal-Insulator Transition 1 Introduction 2 Experimental Section 3 Results and Discussion 3.1 Metal-Insulator Transition in Metallic Perovskite Oxides 3.2 IV Characteristics in LSMO, NNO, and YBCO Thin Films 3.3 Micrometric Scale HRS Areas Induced by C-AFM 3.4 Volume Resistive Switching in Metallic Perovskite Oxides 3.5 Transport Properties of HRS Areas 3.6 Probe Station Measurement for Potential Device Integration 3.7 A Three-Terminal Configuration Proof-of-Principle in LSMO Films 4 Conclusions References Resistive States in Strontium Titanate Thin Films: Bias Effects and Mechanisms at High and Low Temperatures 1 Introduction 2 Materials and Methods 3 Results and Discussion 3.1 Thin Film Characterization 3.2 Electrical Conductivity of Thin Films 3.3 Ionic Conductivity of Thin Films from Isotope Exchange Depth Profile 3.4 DC Voltage in the High Temperature Regime—Migration of Oxygen Vacancies Enforces a Redistribution of Electronic Charge Carriers 3.5 DC Voltage in the Intermediate Temperature Regime—Addressing Resistive States of Fe:SrTiO3 by Affecting the Defect Chemistry 3.6 DC Voltage at Room Temperature—Resistive Switching 4 Conclusions References Single-Crystalline SrTiO3 as Memristive Model System: From Materials Science to Neurological and Psychological Functions 1 Introduction 2 Defect Chemistry Consideration 3 Resistive Switching 3.1 Role of Oxygen Vacancies 3.2 Role of Schottky Barrier 4 Neurological Functions 5 Psychological Functions 5.1 Learning and Forgetting 5.2 Associative Learning 6 Conclusions References Optical Memristive Switches 1 Introduction 2 Optical and Electrical Concepts 2.1 Plasmonics 2.2 Resistive Switching 2.3 Electro-Optical Interaction 3 Optical Memristive Switches 3.1 State-of-the-Art 3.2 Phase Transition Effect 3.3 Valency Change Effect 3.4 Electrochemical Metallization 4 From the Micro- to the Atomic Scale 4.1 Atomic Scale Resistance Switching 4.2 Atomic Scale Plasmonic Switching 5 Summary References Index