Transparent Oxide Electronics – From Materials to Devices

Transparent electronics is emerging as one of the most promising technologies for the next generation of electronic products, away from the traditional silicon technology. It is essential for touch display panels, solar cells, LEDs and antistatic coatings. The book describes the concept of transparent electronics, passive and active oxide semiconductors, multicomponent dielectrics and their importance for a new era of novel electronic materials and products. This is followed by a short history of transistors, and how oxides have revolutionized this field. It concludes with a glance at low-cost, disposable and lightweight devices for the next generation of ergonomic and functional discrete devices. Chapters cover: * Properties and applications of n-type oxide semiconductors * P-type conductors and semiconductors, including copper oxide and tin monoxide * Low-temperature processed dielectrics * n and p-type thin film transistors (TFTs) structure, physics and brief history * Paper electronics Paper transistors, paper memories and paper batteries * Applications of oxide TFTs transparent circuits, active matrices for displays and biosensors Written by a team of renowned world experts, Transparent Oxide Electronics: From Materials to Devices gives an overview of the world of transparent electronics, and showcases groundbreaking work on paper transistors

Table of Contents:
Preface xiii Acknowledgments xv 1 Introduction 1 1.1 Oxides and Transparent Electronics: Fundamental Research or Heading Towards Commercial Products? 1 1.2 The Need for Transparent (Semi) Conductors 3 1.3 Reaching Full Transparency: Dielectrics and Substrates 5 2 N-type Transparent Semiconducting Oxides 9 2.1 Introduction: Binary and Multicomponent Oxides 9 2.1.1 Binary Compounds: the Examples of Zinc Oxide and Indium Oxide 9 2.1.2 Ternary and Quaternary Compounds: the Examples of Indium-Zinc Oxide and Gallium-Indium-Zinc Oxide 12 2.2 Sputtered n-TSOs: Gallium-Indium-Zinc Oxide System 16 2.2.1 Dependence of the Growth Rate on Oxygen Content in the Ar+O2 Mixture and Target Composition 16 2.2.2 Structural and Morphological Properties 18 2.2.3 Electrical Properties 22 2.2.3.1 Effect of oxygen content in the Ar + O2 mixture 22 2.2.3.2 Effect of composition (binary, ternary and quaternary compounds) 24 2.2.3.3 Effect of annealing temperature 27 2.2.3.4 Additional considerations about the conduction mechanisms in oxide semiconductors 30 2.2.3.5 Effect of thickness (ds) 39 2.2.3.6 Electrical stability measurements 39 2.2.4 Optical Properties 41 2.2.4.1 General considerations about the optical measurements 41 2.2.4.2 Effect of oxygen content in the Ar + O2 mixture 43 2.2.4.3 Effect of composition (binary and multicomponent oxides) 44 2.2.4.4 Effect of annealing temperature 46 2.3 Sputtered n-TSOs: Gallium-Zinc-Tin Oxide System 49 2.4 Solution-processed n-TSOs 51 2.4.1 ZTO by Spray-pyrolysis 51 2.4.2 ZTO by Sol-gel Spin-coating 52 2.4.3 GIZO Sol-gel by Spin-coating 52 3 P-type Transparent Conductors and Semiconductors 63 3.1 Introduction 63 3.2 P-type Transparent Conductive Oxides 64 3.3 Thin Film Copper Oxide Semiconductors 66 3.3.1 Role of Oxygen in the Structure, Electrical and Optical Performance 70 3.3.1.1 Structure evaluation 70 3.3.1.2 Electrical properties evaluation 71 3.3.1.3 Optical properties evaluation 74 3.4 Thin Film Tin Oxide Semiconductors 75 3.4.1 Structure, Composition and Morphology of Tin Oxide Films 79 3.4.1.1 Structure evaluation 79 3.4.1.2 Morphology evaluation 84 3.4.2 Electrical and Optical Properties of Tin Oxide Films 84 3.4.2.1 Electrical properties evaluation 84 3.4.2.2 Capacitance measurements 89 3.4.2.3 Optical properties evaluation 92 4 Gate Dielectrics in Oxide Electronics 101 4.1 Introduction 101 4.2 High-k Dielectrics: Why Not? 102 4.3 Requirements 103 4.4 High-k Dielectrics Deposition 106 4.5 Sputtered High-k Dielectrics in Oxide TFTs 106 4.6 Hafnium Oxide 107 4.6.1 Multicomponent Co-sputtered HfO2 Based Dielectrics 117 4.6.2 Multicomponent Dielectrics from Single Target 126 4.7 Tantalum Oxide (Ta2O5) 130 4.7.1 Multicomponent Ta2O5 Based Dielectrics 133 4.8 Multilayer Dielectrics 138 4.9 High-k Dielectrics/Oxide Semiconductors Interface 141 4.10 Summary 146 5 The (R)evolution of Thin-Film Transistors (TFTs) 155 5.1 Introduction: Device Operation, History and Main Semiconductor Technologies 155 5.1.1 Device Structure and Operation 155 5.1.2 Brief History of TFTs 161 5.1.3 Comparative Overview of Dominant TFT Technologies 168 5.2 Fabrication and Characterization of Oxide TFTs 170 5.2.1 N-type GIZO TFTs by Physical Vapor Deposition 171 5.2.1.1 Effect of oxygen content in the Ar + O2 mixture 172 5.2.1.2 Effect of composition (binary, ternary and quaternary compounds) 173 5.2.1.3 Effect of annealing temperature 179 5.2.1.4 Influence of source-drain electrodes material 181 5.2.1.5 Influence of passivation layer 185 5.2.2 N-type GZTO TFTs by Physical Vapor Deposition 187 5.2.3 N-type Oxide TFTs by Solution Processing 189 5.2.3.1 ZTO TFTs by spray-pyrolysis 189 5.2.3.2 ZTO TFTs by sol-gel spin-coating 189 5.2.3.3 GIZO TFTs by sol-gel spin-coating 192 5.2.4 P-type Oxide TFTs by Physical Vapor Deposition 193 5.2.4.1 Cu2O TFTs by sputtering 193 5.2.4.2 SnO TFTs by sputtering 195 5.2.5 N-type GIZO TFTs with Sputtered Dielectrics 196 5.2.5.1 Tantalum-based dielectrics 198 5.2.5.2 Hafnium-based dielectrics 201 6 Electronics With and On Paper 211 6.1 Introduction 211 6.2 Paper in Electronics 212 6.3 Paper Properties 214 6.3.1 Structure, Morphology and Thermal Properties 214 6.3.2 Electrical Properties of the Paper 218 6.3.2.1 The electrical resistivity 218 6.3.2.2 Electrical capacitance 219 6.3.2.3 Paper capacitance in less compact and porous paper structures 220 6.4 Resistivity Behaviour of Transparent Conductive Oxides Deposited on Paper 223 6.5 Paper Transistors 225 6.5.1 Current Transport in Paper Transistors 228 6.6 Floating Gate Non-volatile Paper Memory Transistor 230 6.6.1 Memory Paper Device Feasibility and Stability 233 6.6.2 Memory Selective and Charge Retention Time Behaviors 234 6.7 Complementary Metal Oxide Semiconductor Circuits With and On Paper Paper CMOS 237 6.7.1 Capacitance-Voltage and Current-Voltage Characteristics of n/p-type Paper Transistors 240 6.7.2 N- and P-channel Paper FET Operation 243 6.7.3 CMOS Inverter Working Principles 244 6.7.4 Paper CMOS Performance 246 6.8 Solid State Paper Batteries 249 6.9 Electrochromic Paper Transistors 252 6.10 Paper UV Light Sensors 255 7 A Glance at Current and Upcoming Applications 267 7.1 Introduction: Emerging Areas For (Non-)transparent Electronics Based On Oxide Semiconductors 267 7.2 Active Matrices for Displays 268 7.2.1 Display Market Overview and Future Trends 268 7.2.2 Driving Schemes and TFT Requirements for LCD and OLED Displays 269 7.2.3 Displays With Oxide-based Backplanes 271 7.3 Transparent Circuits 273 7.3.1 Inverters and Ring Oscillators 273 7.3.2 The Introduction of Oxide CMOS 275 7.4 Oxide Semiconductor Heterojunctions 278 7.4.1 Oxide Semiconductor Heterojunctions In the Literature 278 7.4.2 GIZO Heterojunctions Fabricated at CENIMAT 279 7.5 Field effect Biosensors 280 7.5.1 Device Types and Working Principles 280 7.5.2 Oxide-based Biosensors Fabricated at CENIMAT 281 Index

About the Author :
Elvira Fortunato is Associate Professor and Director of Institute for Nanotechnologies, Nanomaterials and Nanosciences at the New University of Lisbon. She is one of the inventors of paper transistors and paper memory and was one of the pioneers of European research on thin-film transistors based on oxide semiconductors. She has been Associate Editor of Rapid Research Letters Physica Status Solidi since November 2006 and is the recipient of several awards, including the award for Scientific Excellence from the Portuguese Science Foundation (2005). She is the author of more than 200 papers and has been an invited speaker at MRS, E-MRS and NAIST. Coauthors at CENIMAT, New University of Lisbon: Rodrigo Ferrão de Paiva Martins, Luís Pereira, Pedro Barquinha.