Thin Film Metal-Oxides (eBook)

Thin Film Metal-Oxides 1
Stoichiometry in Thin Film Oxides –A Foreword 4
1 In Situ Synchrotron Characterization of Complex Oxide Heterostructures 14
1.1 Introduction 14
1.2 Background 15
1.2.1 Perovskites 15
1.2.2 Scattering 18
1.2.3 Spectroscopy 22
1.2.4 X-ray Absorption 24
1.2.4.1 Extended X-ray Absorption Fine Structure (EXAFS) 25
1.2.4.2 X-ray Absorption Near Edge Structure (XANES) 26
1.2.4.3 Dichroism in X-ray Spectroscopy 27
1.2.5 In Situ Surface Spectroscopy 28
1.3 In Situ Monitoring of Complex Oxide Film Growth 29
1.3.1 Substrate 29
1.3.2 Growth Oscillations 31
1.3.3 Case Studies of Oxide Growth 32
1.3.3.1 PLD of SrTiO3 on SrTiO3(001) 33
1.3.3.2 PLD of La1-xSrxMnO3 on SrTiO3(001) 34
1.3.3.3 MOCVD of PbZrxTi1-xO3 on SrTiO3(001) 36
1.4 Complex Oxide Film Structure 40
1.4.1 Interfaces 40
1.4.1.1 The SrTiO3(001) Surface 41
1.4.1.2 The LaAlO3/SrTiO3(001) Buried Interface 42
1.4.1.3 The PbTiO3(001) Surface 44
1.4.1.4 The PbTiO3/SrTiO3(001) Buried Interface 44
1.4.1.5 The La0.7Sr0.3MnO3(001)p Surface 45
1.4.2 Internal Structure: Non-Cubic Films on SrTiO3(001) 47
1.4.2.1 Polydomain Structures 48
1.4.2.2 Monodomain Structures 51
1.4.3 Spectroscopic Studies of Complex Oxides 53
1.4.3.1 A-Site Clustering in La1-xSrxMnO3 53
1.4.3.2 B-Site Electronic Structure in La1-xCaxMnO3 55
1.4.3.3 Polarization Sensitive Near-Edge Structure in Bi4-xNdxTi3O12 and La0.7Sr0.3MnO3 57
1.5 Outlook 58
References 58
2 Metal-Insulator Transition in Thin Film Vanadium Dioxide 63
2.1 Introduction 63
2.2 Material Synthesis 65
2.3 Crystal Structure 69
2.4 The Relationship between Electron Transport and Material Morphology 71
2.5 The Nature of the Insulating State 80
2.6 Energy Band Structure 83
2.7 Optical Properties 90
2.8 Magneto-Transport 94
2.9 Devices 97
References 102
3 Novel Magnetic Oxide Thin Films 107
3.1 Preview 107
3.2 Half Metallic Oxide Thin Films 108
3.2.1 Introduction 108
3.2.2 Chromium Dioxide 110
3.2.3 La1-xSrxMnO3 114
3.2.4 Magnetite 121
3.3 Diluted Magnetic Oxide Semiconductors 123
3.4 Room-Temperature Multiferroic Oxide Thin Films 129
3.4.1 Introduction 129
3.4.2 BiFeO3 129
3.4.3 Multiferroic Composites -- Metamultiferroics 135
3.5 Summary 136
References 137
4 Bipolar Resistive Switching in Oxides for Memory Applications 142
4.1 Introduction and Motivation 142
4.2 Classification of Bipolar Switching Effects 145
4.2.1 Geometrical Localization of the Switching Event 145
4.2.2 Memory Window Considerations 146
4.2.3 Observed Area Dependencies of the Resistive Switching Effect 148
4.3 Distributed Bipolar Switching Effects in Transition Metal Oxides 149
4.3.1 Oxide Dual Layer Memory Element 149
4.3.2 Distributed Bipolar Switching in Complex Perovskites 151
4.4 Localized Bipolar Switching Effects in Transition Metal Oxides 156
4.4.1 Filamentary Switching in Cr-Doped SrTiO3 Single Crystals 156
4.4.2 Filament Fine Structure Analysis with Conductive-Tip AFM 158
4.4.3 Filament Fine Structure Analysis on Thin Film Samples 159
4.4.4 Bipolar Switching Effects in Binary Transition Metal Oxides 163
4.5 Impact of Electrode Materials on Bipolar Switching 168
4.5.1 Workfunction of the Metal 169
4.5.2 Metallic Filament Formation with Cu- and Ag-Electrode 170
4.5.3 Bipolar and Unipolar Switching in One Sample 170
4.6 Device Performance 172
4.7 Summary, Conclusions, and Outlook 174
References 175
5 Complex Oxide Schottky Junctions 179
5.1 Introduction 179
5.2 Schottky Junctions 183
5.2.1 Basic Concepts 183
5.2.2 Current Transport Processes 185
5.2.3 Barrier Height Characterization Techniques 188
5.3 Physics of Complex Oxide Schottky Junctions 189
5.3.1 Dielectric Properties of SrTiO3 189
5.3.2 SrRuO3/Nb:SrTiO3 Junction -- The Canonical Complex Oxide Heterojunction 193
5.3.3 Schottky Barrier Height Dependence on the Chemical Composition in La1-xSrxMO3/Nb:SrTiO3 Junctions 197
5.3.4 Termination Control of the Schottky Barrier Height 197
5.4 Applications of Complex Oxide Schottky Junctions 200
5.4.1 Magnetoresistance at Manganite/Nb:SrTiO3 Junctions 200
5.4.2 Carrier Density Tuning by Photocarrier Injection 207
5.4.3 Resonant Tunneling Through Metal-Induced Interface States 209
5.4.4 Resistive Switching at Complex Oxide Schottky Junctions 211
5.5 Summary 211
References 212
6 Theory of Ferroelectricity and Size Effects in Thin Films 215
6.1 Introduction 216
6.2 Methodology 219
6.2.1 First-Principles Theoretical Methodology 219
6.2.2 Effective Hamiltonian Methodology 221
6.2.3 Effective Hamiltonian for Thin Films 222
6.2.4 Phenomenology 224
6.2.5 Results of Theoretical Analysis 225
6.2.5.1 Free-Standing Slabs of ABO3 225
6.2.5.2 Interfaces and Superlattices 230
6.2.5.3 Ferroelectricity in Nano-Thin Films of BaTiO3 232
6.2.5.4 Domains and Inhomogeneities in Ferroelectric Thin Films 238
6.3 Summary 239
References 240
7 High-Tc Superconducting Thin- and Thick-Film--Based Coated Conductors for Energy Applications 242
7.1 Introduction 242
7.1.1 Second-Generation Superconducting Wire Architectures 244
7.2 Role of Low Angle Grain Boundaries 246
7.3 Crystal Defects and Flux Pinning 247
7.4 Enhancement of Self-Field Jc 250
7.5 Introduction of Artificial Flux Pinning Nanostructures for Enhancement of In-Field Jc 253
7.5.1 Self-Assembled Nanostructures 254
7.6 Concluding Remarks 259
References 259
8 Mesostructured Thin Film Oxides 263
8.1 Introduction 263
8.2 Synthesis and Characteristics of Mesostructured Oxides 265
8.2.1 Sol--Gel Cooperative Assembly Chemistry 265
8.2.2 Mesostructured Thin Films: Fabrication and Characteristics 267
8.3 Nanoscale Phenomena in Functional Mesostructured Thin Films 269
8.3.1 Nanocrystalline Transition Metal Oxide Mesoporous Frameworks 269
8.3.2 Assembly and Nanocrystallization of Titania Mesoporous Thin Films 272
8.4 Multi-Compositional Mesostructured Thin Film Oxides 274
8.4.1 Optical, Electrical, and Electrochemical Applications 274
8.4.2 Photocatalytic and Electrochromic Applications 277
8.4.3 Photovoltaic/Solar Cell Applications 281
8.5 Conclusions 283
References 283
9 Applications of Thin Film Oxides in Catalysis 288
9.1 Introduction 288
9.2 Tuning Electronic Properties of Novel Metal Oxide Nanocrystals Using Interface Interactions: MoO3 Monolayers on Au(111) 290
9.2.1 Background and Introduction 290
9.2.2 Computational Details 291
9.2.3 Results and Discussion 292
9.2.4 Concluding Remarks 298
9.3 Ultrathin Titania Films as Active Supports for Supported Au Catalysts 298
9.3.1 Background and Introduction 298
9.3.2 Motivation 299
9.3.3 Choice of Model 300
9.3.4 Computational Details 300
9.3.5 Results and Discussion 302
9.3.6 Concluding Remarks 306
References 307
10 Design of Heterogeneous Catalysts and the Application to the Oxygen Reduction Reaction 309
10.1 Introduction 310
10.2 Theory 311
10.3 Details of Calculations 312
10.3.1 Cluster Model 312
10.3.2 Slab Model 313
10.4 Details of Experiments 314
10.5 Results 315
10.5.1 Cluster Model 315
10.5.1.1 Cluster Size 317
10.5.1.2 Cluster Composition 322
10.5.2 Slab Model 323
10.5.2.1 Electronic Structure 324
10.5.2.2 Oxygen Adsorption 326
10.5.3 Experiments 328
10.5.3.1 Stress 329
10.5.3.2 Electron Structure 330
10.5.3.3 Catalytic Performance 332
10.6 Discussion 332
10.7 Conclusions 333
References 334
Index 335