Introduction to Electronic Devices

T​his textbook offers a comprehensive introduction to the basic principles ruling the working mechanism of the most common solid-state electronic devices. It covers the physics of semiconductors and the properties of junctions of semiconductors with semiconductors, metals, and insulators. The exposition makes a minimal use of quantum mechanics concepts and methods. On the other hand, it avoids the pure phenomenological description of the properties of electronic devices. Thus, using a semi-classical approach the book provides a rigorous treatment of the subject. The book is addressed to undergraduate students of scientific and technological faculties as well to professionals who wish to be introduced to the basic principles of electronic devices. Preface Contents 1 The Physical Background 1.1 Introduction 1.2 The Phenomenology of Semiconductors 1.3 Electrons in Solids 1.3.1 Orbitals Splitting and Coupled Oscillators 1.3.2 Crystals, Periodic Potentials and Energy Gaps 1.3.3 Electron Distributions in Energy Levels 1.3.4 The Band Diagram 1.4 The Statistics of Electrons and Holes 1.4.1 The Density of States 1.4.2 The Intrinsic Fermi Level 1.4.3 Doping 1.5 Charge Transport: The Drift-Diffusion Model 1.5.1 Thermal Velocity 1.5.2 Drift Current 1.5.3 Diffusion Current 1.6 Non-uniform Distribution of Dopant Atoms and Built-in Potential 1.6.1 Quasi-neutrality Condition 1.7 Summary Further Reading 2 The Metal-Semiconductor Junction 2.1 Introduction 2.1.1 The General Rule of Junctions at the Equilibrium 2.2 The Metal-Semiconductor Junction at the Equilibrium 2.3 Biased Metal-Semiconductor Junction 2.3.1 The Capacitance of the Junction 2.3.2 The I/V Characteristics 2.3.3 Barrier Height Lowering 2.4 Non-rectifying Metal-Semiconductor Contact 2.4.1 Ohmic Contact 2.4.2 Tunnel Ohmic Contacts 2.4.3 Space Charge Limited Current 2.5 Surface States 2.6 Summary Further Reading 3 Generation and Recombination Processes 3.1 Introduction 3.2 The Continuity Equation 3.3 Generation and Recombination Phenomena 3.3.1 Generation and Recombination Rates 3.3.2 Traps and Recombination Centers 3.4 The Shockley-Hall-Read Generation-Recombination Model 3.4.1 Example of Application of the SHR Model: The Dynamics of Generation-Recombination Phenomena 3.4.2 The Generation-Recombination Function for Direct Band Gap Materials 3.5 Summary Further Reading 4 PN Junction 4.1 Introduction 4.2 PN Junction at the Equilibrium 4.2.1 Removal of Charge Discontinuity at the Depletion Layer Border 4.2.2 Physical Configurations 4.3 The Current in the PN Junction 4.3.1 Ideal Current 4.3.2 Generation and Recombination Current 4.4 Capacitive Effects 4.4.1 Minority Charge Storage and Diffusion Capacitance Density 4.5 Breakdown Phenomena 4.5.1 Avalanche Effect 4.5.2 Zener Effect 4.6 Summary Further Reading 5 Negative Differential Resistance Effects 5.1 Introduction 5.2 Tunnel Diode 5.3 NDR Behavior in GaAs 5.4 Gunn Oscillations 5.5 Summary Further Reading 6 Bipolar Junction Transistor 6.1 Introduction 6.2 The Ideal Transistor 6.2.1 Electron Current in the Active Zone 6.3 Current Gain 6.3.1 Base Recombination Current 6.3.2 Forward Hole Current in the Emitter 6.3.3 Numerical Comparison of αT and γ 6.3.4 Total Current Gain 6.4 BJT Operative Conditions 6.5 Non Ideal Effects 6.5.1 Early Effect 6.5.2 Emitter Band-Gap Narrowing 6.5.3 Small Base Current 6.5.4 High Injection Effects 6.6 Physical Effects in Real BJT 6.7 Dynamic Response 6.7.1 Junction and Diffusion Capacitances 6.8 Summary Further Reading 7 Heterojunctions 7.1 Introduction 7.2 Band Diagram 7.2.1 Staggered Bandgaps 7.2.2 Straddled Bandgaps 7.3 Electric Field and Built-In Potential 7.4 The Quasi-electric Field 7.5 Current-Voltage Relationship 7.5.1 Thermionic Current 7.6 Heterojunction Bipolar Transistor 7.6.1 Graded Band Gap 7.7 Summary Further Reading 8 Metal-Oxide-Semiconductor Junction 8.1 Introduction 8.2 Band Diagram and Electrostatic Quantities at the Equilibrium 8.2.1 Relation Between Potential and Charge Carrier Concentrations 8.3 The MOS Under Bias 8.4 The C/V Curve 8.4.1 Minority Charges Generation in the Depletion Layer 8.5 Summary Further Reading 9 Field Effect Transistors 9.1 Introduction 9.2 Channel Charge Modulation and the Threshold Voltage 9.3 Metal Oxide Semiconductor Field Effect Transistor 9.3.1 Channel Length Modulation 9.3.2 Body Effect 9.3.3 Subthreshold Current 9.3.4 Transit Time 9.4 Short Channel MOSFET 9.4.1 Threshold Voltage Modulation 9.4.2 Drain Induced Barrier Lowering 9.4.3 Velocity Saturation 9.4.4 Transit Time 9.4.5 Scaling 9.5 CMOS Configuration 9.6 Metal Semiconductor Field Effect Transistor (MESFET) 9.7 High Electron Mobility Transistor: HEMT 9.8 Summary Further Reading Appendix A Elements of Classic Physics A.1 Newtonian Mechanics A.2 Electromagnetism Appendix B Basic Principles of Quantum Mechanics B.1 Waves and Particles B.2 Operators and State Functions B.3 The Schrödinger Equation B.3.1 Potential Well and Discrete Energy Levels Appendix C The Chua Formalism of Electric Network Elements Appendix D The SHR Generation-Recombination Function Appendix E Numerical Examples of Rectifying Junctions E.1 Metal-Semconductor Junction E.2 PN Junction Appendix F Majority Current in a BJT with a Linearly Doped Base Further Reading