Table of Contents
Preface xiii
Acknowledgments xv
Chapter 1 Introduction to LEDs 1
1.1 Basic Operation 1
1.1.1 The p-n Junction 1
1.1.1.1 No Applied Voltage 2
1.1.1.2 Applying Forward-Bias 2
1.1.1.3 Applying Reverse-Bias 3
1.1.2 LED Operation 4
1.1.2.1 Similarity to a Diode 4
1.1.2.2 Crossing the Barrier 4
1.1.3 LED Evolution 4
1.1.3.1 The First LED 5
1.1.3.2 Doping Materials 5
1.1.4 Voltage and Current Requirements 8
1.1.4.1 Manufacture of LEDs 8
1.1.4.2 Parallel and Series Operations 10
1.1.4.3 Current Limitation Considerations 12
1.2 Types, Functions, and Applications 18
1.2.1 Types of LEDs 18
1.2.1.1 Physical Characteristics 18
1.2.1.2 Colors 20
1.2.1.3 Flashing LEDs 21
1.2.1.4 LED Displays 22
1.2.2 Applications 23
1.2.2.1 Lighting 23
1.2.2.2 Other Applications 24
Chapter 2 Fundamentals of Light 27
2.1 Properties of Light 27
2.1.1 Speed of Light 27
2.1.2 Photons 28
2.1.3 Planck's Constant 28
2.1.4 Frequency, Energy, and Light 29
2.1.5 Frequency and Wavelength 29
2.1.5.1 Frequency 30
2.1.5.2 Frequency of Waves 30
2.1.5.3 The Electromagnetic Spectrum 30
2.1.6 Spectral Power Distribution 31
2.1.6.1 Incandescent Light 32
2.1.6.2 Fluorescent Light 32
2.2 The CIE Color System 33
2.2.1 The Maxwell Triangle 33
2.2.1.1 Overview 33
2.2.1.2 Limitations 34
2.2.1.3 The Spectral Locus 34
2.2.2 CIE Theoretical Primaries 35
2.2.3 CIE Chromaticity Chart 35
2.3 LED Light 36
2.3.1 Comparing LEDs 37
2.3.2 White Light Creation Using LEDs 37
2.3.2.1 White Light Creation by Mixing Colors 37
2.3.2.2 White Light Creation Using Phosphor 37
2.3.3 Intensity of an LED 40
2.3.3.1 Candlepower 40
2.3.3.2 The Candela 41
2.3.4 On-Axis Measurement 41
2.3.5 Theta One-Half Point 42
2.3.6 Current and Voltage Considerations 43
2.3.7 Lumens, Candelas, Millicandelas, and Other Terms 43
2.3.7.1 Lumens 44
2.3.7.2 Lumens per Watt and Lux 45
2.3.7.3 Watt Dissipation 45
2.3.7.4 Steradian 46
2.3.7.5 Luminous Energy 47
2.3.7.6 Illuminance 48
2.3.7.7 Lighting Efficiency 48
2.3.7.8 Color Temperature 49
2.3.7.9 Representative Lighting Color Temperature 49
2.3.8 LED White Light Creation 50
2.3.8.1 Wavelength Conversion 50
2.3.8.2 Color Mixing 51
2.3.8.3 Homoepitaxial ZnSe 51
Chapter 3 LEDs Examined 53
3.1 P-N Junction Operation 53
3.1.1 Semiconductor Material 54
3.1.2 Basic Concepts of Atoms 54
3.1.2.1 Electrical Charge 55
3.1.2.2 Band Theory 55
3.1.3 Energy Bands 55
3.1.4 Conduction and Valence Bands of Conductors, Semiconductors, and Insulators 56
3.1.5 Equilibrium 57
3.1.5.1 Depletion Region Operation 58
3.1.5.2 Bias Effect 59
3.2 Diodes and LEDs 60
3.2.1 LED Operation 60
3.2.2 Color of the Light Emitted by an LED 61
3.2.3 Light Production 62
3.3 Organic Light-Emitting Diodes 63
3.3.1 Overview 63
3.3.2 Comparing Technologies 64
3.3.2.1 LCDs versus OLEDs 64
3.3.3 Types of Displays 65
3.3.3.1 PMOLED 65
3.3.3.2 AMOLED 66
3.3.4 Limitations of OLEDs 68
3.3.4.1 Lifetime of OLEDs 68
3.3.4.2 Fabrication and Ramp-Up Cost 69
3.3.5 OLED TV 69
3.3.6 Other Markets 71
3.4 LED Drivers 72
3.4.1 Rationale for Use 73
3.4.2 Using PWM 74
3.4.3 Driver Definition 75
3.4.4 Driver Connection 75
3.4.5 Types of Drivers 75
3.4.5.1 Boost LED Drivers 76
3.4.5.2 Step-Down LED Drivers 76
3.4.5.3 Buck-Boost LED Drivers 77
3.4.5.4 Multitopology Driver 77
3.4.5.5 Pump LED Driver 77
3.5 Summary 78
Chapter 4 LEDs and Lighting 79
4.1 Rationale 80
4.1.1 Incandescent Lightbulbs 80
4.1.1.1 Economics of Use 81
4.1.2 Compact Fluorescent Lightbulbs 82
4.1.2.1 Cost Reduction 82
4.1.2.2 Utility Subsidization 83
4.1.2.3 The Federal 2007 Energy Bill 84
4.1.2.4 Economics of Use 84
4.1.2.5 Disposal Problems 85
4.1.3 LED Lightbulbs 86
4.1.3.1 Purchase Considerations 86
4.1.3.2 Quality of Light 88
4.2 High-Brightness (HB) LEDs 90
4.2.1 Overview 91
4.2.1.1 Metal-Organic Chemical-Vapor Deposition System 91
4.2.1.2 Initially Developed HB LEDs 92
4.2.1.3 Utilization 92
4.2.2 Fabrication Forms 93
4.2.3 ac versus dc Power 93
4.2.3.1 Seoul Semiconductors 94
4.2.3.2 Lynk Labs 95
4.2.4 HB-LED Output 96
4.2.5 Energy Star Program Developments 97
4.2.6 Outdoor Lighting Developments 98
4.2.7 Cities Discovering LEDs 99
4.2.8 Lighting Science Group 100
4.2.9 OSRAM Opto Semiconductors 101
Chapter 5 LEDs in Communications 103
5.1 Remote Control and Infrared LEDs 103
5.1.1 Overview 104
5.1.2 The Infrared Region 104
5.1.2.1 Rationale for Use 104
5.1.2.2 Frequency and Wavelength 104
5.1.3 Evolution in the Use of IR 106
5.1.4 IR Remote Operation: IR Port 106
5.1.5 Types of IR Devices 107
5.1.5.1 Emitters 107
5.1.5.2 Detector 107
5.1.5.3 Photo Interrupter 107
5.1.5.4 Photo Reflector 108
5.1.5.5 IR Transceiver 108
5.1.6 TV Remote Control 109
5.1.7 The IR Signal 109
5.1.7.1 ASK Modulation 109
5.1.7.2 FSK Modulation 110
5.1.8 Interference 110
5.1.9 Inside a TV Remote Control 111
5.1.9.1 Operation 111
5.1.9.2 Printed Circuit Board 112
5.1.10 Remote Control LEDs 113
5.1.10.1 Wavelengths and Fabrication 113
5.1.10.2 Technical Details 113
5.1.10.3 Cost 114
5.1.11 IR Detection with IR Photodiode 114
5.1.11.1 Overview 114
5.1.11.2 Modes 115
5.1.11.3 Composition 116
5.1.11.4 Packaging 116
5.1.11.5 Operation 117
5.1.12 Selecting a Resistor 117
5.1.12.1 Limiting the Value of the Resistor 118
5.1.12.2 Maximum Resistance 118
5.2 Ethernet Networking 119
5.2.1 Fiber-Optic Cable 120
5.2.1.1 Decibels Power Measurements 120
5.2.1.2 Single versus Dual Cables 121
5.2.1.3 Cable Composition 122
5.2.1.4 Types of Fiber Cable 122
5.2.1.5 Fiber and Wavelength 123
5.2.2 FOIRL and 10BASE-F 124
5.2.2.1 Overview 125
5.2.2.2 Optical Transceiver 125
5.2.2.3 The Fiber Hub 125
5.2.2.4 Fiber Adapter 126
5.2.2.5 Wire and Fiber Distance Limitations 126
5.2.3 10BASE-F 127
5.2.3.1 10BASE-FL 127
5.2.3.2 10BASE-FB 129
5.2.3.3 10BASE-FP 129
5.2.4 Optical Media Support 129
5.2.5 Fast Ethernet 130
5.2.5.1 100BASE-FX 130
5.2.5.2 100BASE-SX 130
5.2.6 Gigabit Ethernet 131
Chapter 6 Comparing LEDs and Laser Diodes 133
6.1 The Laser Diode 133
6.1.1 Emission of Coherent Light by Laser Diodes 134
6.1.1.1 The Quantum Process 134
6.1.1.2 Use of Mirrors 136
6.1.2 Reviewing LED and Laser Diode Operations 137
6.1.3 Evolution of Laser Diodes 137
6.1.4 Types of Laser Diodes 138
6.1.4.1 Edge-Emitting Laser Diode 138
6.1.4.2 Double Heterostructure Laser 140
6.1.4.3 Quantum Well Laser 140
6.1.4.4 Vertical-Cavity Surface-Emitting Laser (VCSEL) 141
6.1.4.5 Trade-offs between Various Laser Diodes 143
6.1.4.6 Vertical External Cavity Surface-Emitting Laser 143
6.2 Comparing Laser Diodes and LEDs 143
6.2.1 Comparing Operational Characteristics 143
6.2.2 Performance Characteristics 144
6.2.2.1 Speed 144
6.2.2.2 Peak Wavelength 145
6.2.2.3 Power Coupling 145
6.2.2.4 Spectral Width 145
6.2.2.5 Emission Pattern 145
6.2.2.6 Linearity 146
6.2.2.7 Luminous Efficacy 147
6.2.2.8 Drivers 147
6.2.3 Safety 148
6.2.4 Applications 148
6.2.4.1 Commercial Applications 149
6.2.4.2 Data Communications 150
6.2.4.3 Dental Applications 151
6.2.4.4 Illumination Application 151
6.2.4.5 Medical Application 151
6.2.4.6 Military Applications 151
Chapter 7 The Evolving LED 153
7.1 Lighting 153
7.1.1 Increasing LED Density 154
7.1.2 Light Output per LED 154
7.2 Communications 157
7.3 Organic LEDs 158
7.3.1 Display Utilization 158
7.3.2 Advantages 158
7.3.3 Current Deficiencies 159
7.3.4 Lighting 160
Index 161
