FOR ENGINEERS AND
ELECTRONIC DESIGNERS
Emanuel Eduardo Pires Vaz.
DEDICATORY
IN NOMINE PATRI:
Professor Emanuel Vaz, a prominent scholar in Europe, is the author of this book and worked as a physicist in the Centre for Nuclear Physics and Electronics of the Faculty of Science of University of Porto; now he is a professional engineer and has been actively involved in the promotion and enhancement of quality and productivity in Portugal since 1981. Now he is professor of applied mathematics at Porto and individual member of the New York Academy of Sciences.
This course has for ground a post-graduation of his son João Pedro B. Vaz in Cambridge University continuing with the lessons at Colorado State University, University of Pennsylvania, Instituto Superior de Engenharia do Porto, and developing practical works with the students at the Faculty of Engineering of the University of Porto.
It is a serious work on semiconductors for engineering, technicians and electronic designers.
The mathematics used here are only those necessary to understand the phenomena, and the multitude of graphs clearly illustrates the theory and practice of semiconductors.
This book is devoted to electronic theory of semiconductors and power electronics; some important applications of theories are presented. The author and his entire team would like to express its gratitude to all institutions, some colleagues and students, who encouraged him to adapting their lessons for publication.
Maria Irene J. Pires
Chapter 1
1.1. Effects of Static Electricity. Static electricity has long been a problem in many industrial and commercial operations and is a serious hazard especially in explosive atmospheres and in areas where flammable solvents or materials are present.
Not only is the sudden discharge, or arcing, of static electricity responsible for fires and explosions, but it also causes losses in the millions of dollars to manufacturers in machinery downtime and lost man-hours, and in product loss particularly in the semiconductor and electronics industries where static sensitive components are degraded or destroyed by only a few volts of static electricity. For the user of sophisticated electronics, static causes loss of memory, false inputs, etc., to electronic memory equipment such as computers, data terminals and word processors.
Chapter 2.
2.1. Semiconducting materials. A semiconductor is a solid material that has electrical conductivity in between that of a conductor and that of an insulator; it can vary over that wide range either permanently or dynamically. Semiconductors are tremendously important in technology. Semiconductor devices, electronic components made of semiconductor materials, are essential in modern electrical devices. Examples range from computers to cellular phones to digital audio players. Silicon is used to create most semiconductors commercially, but dozens of other materials are used as well.
CHAPTER 4.
4.1. P-N Junction. One of the crucial keys to solid state electronics is the nature of the P-N junction. When p-type and n-type materials are placed in contact with each other, the junction behaves very differently than either type of material alone. Specifically, current will flow readily in one direction (forward biased) but not in the other (reverse biased), creating the basic diode. This non-reversing behaviour arises from the nature of the charge transport process in the two types of materials.
The open circles on the left side of the junction above represent "holes" or deficiencies of electrons in the lattice which can act like positive charge carriers. The solid circles on the right of the junction represent the available electrons from the n-type dopant. Near the junction, electrons diffuse across to combine with holes, creating a "depletion region". The energy level sketch above right is a way to visualize the equilibrium condition of the P-N junction. The upward direction in the diagram represents increasing electron energy.
10.22. LDMOS transistors rise to occasion[1].
More than ten years ago LDMOS transistors were introduced as a replacement of bipolar transistors for RF power applications. One of the last rich application areas in which bipolar devices were used was the 3-4 GHz microwave area, such as S- band radar. Main reason for this was that earlier generations of LDMOS showed a similar performance at 3 GHz
33.11.5. Time Domain Analysis.
The time domain analysis of the steady state current waveform for an R-L load has been presented here. Under steady state the load current waveform in a particular output cycle will repeat in successive cycles and hence only one square wave period has been considered. Let t = 0 be the instant when the positive half cycle of the square wave starts and let I0 be the load current at this instant. The negative half cycle of square wave starts at t = 0.5T and extends up to T. The circuit differential equation valid during the positive half cycle of voltage can be written as below:
INDEX
CHAPTER 1.
- Effects of Static Electricity.
- 1.2. Theory.
- Insulators and conductors.
- Two Basic Methods for Neutralizing Static.
- Conductivity Method.
- Replacement Method –Ionization.
- Methods of Ionization.
- An electrically powered static neutralizer.
- Nuclear powered static eliminators.
- Induction type equipment.
- Methods of Ionization.
- Guidelines for selecting equipment.
- Ionizing air blowers.
- Static bars
- Ionizing air guns and nozzles
- Ionizing air blowers.
- Static removal dust systems.
- Static charge meters.
- Conductive wrist straps.
- Conductive and antistatic materials.
- 1.6.4. Antistatic garments.
- Electrostatic discharge (ESD).
- Causes of ESD.
- Sparks.
- Prevention.
- Simulation and testing.
CHAPTER 2
2.1. Semi conducting materials.
2.2. Nuclear structure.
2.3. Energy –momentum dispersion.
2.4. Carrier generation and recombination.
2.5. Doping
2.5.1. Dopants.
2.5.2. Carrier concentration.
2.6. Effect on band structure.
2.6.1. Free electron model.
2.6.1.1. The free electron model of a metal.
2.7. The Kronig-Penney model.
2.8. Energy bands of semiconductors.
2.8.1. Energy band diagrams of common semiconductors.
2.8.2. Simple energy band diagram of a semiconductor.
2.9. Temperature dependence of the energy band gap.
2.10. Doping dependence of the energy band gap.
2.11. Electrons and holes in semiconductors.
2.11.1. Holes are missing electrons.
2.12. The effective mass concept.
2.12.1. Detailed description of the effective mass concept.
2.13. Band structure of silicon.
2.13.1. Simplified E-K diagram of silicon.
2.13.2. Effective mass and energy band minima and maxima of Ge, Si, and GaAs.
2.13.3. Effective mass for conductivity calculations.
2.14. Derivation of the Kronig-Penney model.
CHAPTER 3
- Atomic Structure.
3.1.1. Crystal Structure.
3.1.1.1. Unit cell.
3.1.1.2. Classification of crystals by symmetry.
3.1.1.3. Angles of the 7 basic crystalline structure.
3.1.1.4. The Bravais lattices.
3.1.1.5. Point and space groups.
3.1.1.6. Crystal energy bands.
3.2. Physical properties.
3.2.1. Defects in crystals.
3.2.2. Crystal symmetry and physical properties.
3.2.3. Miller indices.
3.3. Energy band formation.
3.3.1. Parabolic band.
3.3.2. Non-parabolic band.
3.3.3. Full band structure.
3.4. Fermi Dirac statistics.
3.4.1. Which distribution to use.
3.4.2. A derivation.
3.4.3. Another derivation.
CHAPTER 4
4.1. P-N junction.
4.2. Depletion region.
4.2.1. Depletion region details.
4.3. Bias effect on electrons in depletion zone.
4.3.1. Equilibrium of junction.
4.3.2. Reverse bias.
4.3.3. Forward bias.
4.4. P-N energy bands.
4.4.1. Forward biased conduction.
CHAPTER 5
5.1 Conduction in semiconductors
5.2. Conduction in metals.
5.2.1. Drift velocity.
5.2.2. Charge density.
5.2.3. Current density.
5.2.4. Conductivity.
5.2.5. Resistance.
5.3. Conduction in intrinsic semiconductors.
5.5. Recombinations.
5.5. Intrinsic concentration.
5.6. Conductivity.
5.7. n-type and p-type semiconductors.
5.8. n-type semiconductor.
5.9. p-type semiconductor.
5.10. Mass-action law.
5.11. Electrical neutrality.
5.12. Conductivity.
5.13. Diffusion current.
5.14. Recombination lifetime.
CHAPTER 6.
6.1. The open-circuited p-n junction.
6.2. Depletion region.
6.3. Built-in potential.
6.4. The short-circuited p-n junction.
6.5. The biased p-n junction.
6.5.1. Reverse bias.
6.5.2. Forward bias.
6.6. Hall effect.
CHAPTER 7.
7.1. What power electronics is.
7.1.1. Power converters as switching matrices.
7.1.2. The role of power filters.
7.2. Diodes.
7.3. Transient V-I characteristic of a diode.
7.4. Pulse number (Idriss number).
7.5. Simplifying assumptions.
7.6. Single-phase half-wave diode rectifier.
7.7. Single-phase half-wave diode rectifier with R/L load.
7.8. Single- phase half-wave diode rectifier – other loads.
7.9. Single- phase full –wave rectifiers and continuous current.
7.10. Two- pulse rectifier with inductance filter.
7.11. Power relationships.
7.12. Three-phase diode rectifiers.
7.13. Generalized center-tap rectifier.
7.15. Application of diode rectifiers.
7.16. Equilibrium carrier concentrations.
7.16.1. PN junctions.
7.16.3. Diode equation- neglecting recombination.
7.16.4. Diode equation with recombination.
7.16.5. Reverse saturation current.
CHAPTER 8
8.1. Transistor operation.
8.2. NPN common emitter switch.
8.3. NPN emitter follower switch.
8.4. Bipolar junction transistor.
8.5. Transistor as current amplifier.
8.6. Transistor structure.
8.7. Constraints on transistor operation.
8.8. Transistor maximum values.
8.9. Transistor switch example.
8.10. NPN common emitter switch.
8.11. NPN emitter follower switch.
8.12. Current transfer ratio.
8.13. Emitter injection efficiency.
8.14. Avalanche multiplication ratio.
8.15. Reverse saturation current.
CHAPTER 9.
9.1. Transistor internal parameters.
9.1.1. Alpha cut-off.
9.1.2. Mathematical analysis.
9.2. Transition capacitance.
9.3. Fields in the space charge.
9.4. Mathematical analysis.
9.5. Parametric considerations.
9.6. Hybrid-pi model.
9.7. BJT parameters.
9.8. Bipolar transistor network.
9.9. Two-port network.
9.9.1. Defining equations.
9.9.2. Impedance parameters.
9.9.3. Review of One-Port Circuits.
9.9.4. Generalization to non linear circuits.
9.9.4.1. Finding the model parameters.
9.9.4.2. Combinations of two –port models.
9.9.5. Principle of reciprocity.
9.9.5.1. T-Network Model.
9.9.5.2. 
-network model.
9.9.6. Cascaded two-port networks.
CHAPTER 10.
10.1. The transistor at high frequencies.
10.1.1. Transit time, Dispersion Effect.
10.2. Alpha (
Current Frequency.
10.3. High Frequency Equivalent Circuit.
10.3.1. Frequency Comparison of Point-Contact and Junction Transistors.
10.4. High Frequency Circuits.
10.4.1. I-F Amplifiers.
10.4.2. I-F Coupling Circuits.
10.4.3. Neutralization.
10.5. RF Amplifiers.
10.6. Limiters.
10.7. Mixers.
10.7.1. Power Suppliers.
10.8. Transistor Life Expectancy.
10.9. Transistor Ruggedness.
10.10. Soldering Techniques.
10.11. Temperature Effects.
10.12. Transient Protection.
10.13. Hybrid Parameters.
10.13.1. Significance and Derivation.
10.13.2. Resistance Parameters in Terms of Hybrid Parameters.
10.14. Printed Circuit Techniques.
10.15. Large Signal Models. The Ebers Moll Model.
10.16. Base-width modulation.
10.17. Heterojunction.
10.18. Active mode operation.
10.18.1. A sweeping collector voltage with base current constant in the saturation region.
10.18.2. Sweeping collector voltage with base current constant.
10.18.3. Sweeping collector voltage with base current constant. Other curves.
10.18.4. Sweeping collector to emitter vs collector current for various base currents.
10.18.5. Elementary diode resistor transistor model.
10.18.6. Current source model of transistor.
10.19. Bipolar transistors.
10.20. Field- effect transistors.
10.21. Schottky barrier.
10.21.2. Bipolar junction transistor.
10.21.3. MESFET.
10.21.4. The formation of one transistor.
10.22. LDMOS transistors rise to occasion.
10.22.1. LDMOS Technology Evolution.
10.22.2. LDMOS performance evolution at 3.6 GHz.
10.22.3. Power technology overview.
10.22. 4. Problems on Bipolar Junction Transistor Theory.
10.23. Analytic method for transistor oscillators design.
CHAPTER 11
11.1. Thyristors, AC/DC converters and other naturally commuted circuits.
11.1.1. Type 2 switch thyristor.
11.2. Steady –State V-I Characteristic of a Thyristor.
11.3. Two-Transistor Analogue for Explaining Thyristor turn-on.
11.4. Gate characteristics.
11.5. Replacement of ignitrons by thyristors.
11.6. Transient V-I Characteristic of a Thyristor.
11.7. Thyristor protection.
11.7.1. Average dissipation at low switching rate.
11.7.2. Average dissipation at high switching rate.
11.7.3. Transmission line for transient thermal analysis.
11.7.4. Cooling of power switching semiconductor devices.
11.8. Contact thermal resistance.
11.9. Heat-sinking for diodes and thyristors.
11.9.1. High- frequency switching.
19.9.2. Heat-sinking for IGBTs.
11.9.3. Heat-sinking for power MOSFETs.
Problem 1.11. Heat-sink design for a diode.
Problem 2.11. Heat –sinking design for an IGBT-repetitive operation at high duty cycle.
Problem 3.11. Heat-sinking for power MOSFETs –repetitive operation at high peak current, low duty cycle.
Problem 4.11. Heat-sink design for a MOSFET-repetitive operation at high duty cycle.
Problem 5.11. Two thermal elements on a common heat-sink.
Problem 6.11. Six thermal elements in a common package.
- TRIACS.
- Gate turn-off thyristors, (GTOS).
11.11.1. Switching characteristics.
11.11.2. Regenerative snubbers.
11.12. Bipolar Power or Junction Transistors, (BPTS or BJTS).
11.13. Power MOSFETS.
11.13.1. V-I Characteristics.
11.13.2. Safe Induction Transistors, (SOA).
11.14. Static Induction Transistors, (SITS).
11.15. Insulated gate bipolar transistors, (IGBTS).
11.15.1. Switching characteristics and thermal impedance.
11.15.2 MOS-CONTROLLED THYRISTORS (MCTS).
11.16. Integrated gate-commuted thyristors, (IGCTS).
11.7. Large band- gap materials for devices.
11.18. Power integrated circuits, (PICS).
11.19. Two pulse AC/DC converter operating as a controlled rectifier.
11.20. AC/DC converter as a linear amplifier.
11.21. AC/DC converter as a DC motor drive.
11.22. Why do you use feedback control?
11.23. Goals for this lesson.
11.24. Some examples.
11.24.1. Here’s another situation.
11.24.1.1. What you’ll need.
11.26. Proportional Control Systems.
11.27. What is a proportional control system?
11.28. Steady State Analysis.
11.28.1. Problem.
11.28.1.1. Problem.
11.29. What does it all mean?
11.29.1. Calculating SSE.
11.29.2. Example/Experiment E1.
11.29.3. Example/Experiment E2.
11.29.4. Example/Experiment E3.
11.29.5. Example/Experiment E4.
11.30. Getting the Closed Loop Transfer Function.
11.30.1. Question.
11.30.2. Control system problem.
11.31. Implementing Proportional Controllers.
11.31.1. Analogue Implementation.
11.32. Two-pulse semi converters.
11.33. Two-pulse dual converter.
11.33.1. Study of 3-phase line commuted thyristor converter circuit.
11.33.2. Circuit Descriptions and principles.
11.33.3. Triggering circuit.
11.33.4. Harmonic Analysis of the Load Voltage and Load Current waveforms.
11.33.5. Time domain Analysis.
11.34. Analysis of the single-phase full bridge inverter.
11.35. Glossary.
Post face.
Postface
The advances in semiconductors over the past two decades have been considerable. The author of this book has contemplated the contribution and benefits from the shared experiences concerning research and development activities in his university. This book offers a fertile ground between providers and users, buyers and sellers, academics and industrialists. It contains the theory of semiconductors, and applications in power electronics which should have any technician or engineer. There are some questions at the end of each chapter, some are resolved, and others are applicable to computer programs, which are used at the Faculty of Engineering of the University of Porto at the ISEP at Colorado State University and at the University of Pennsylvania; many other applications of the theory are part of the portfolio of the author. A CD-ROM accompanies this textbook with some excerpts of the theories whose candidates for their master or PhD degrees have submitted to SEIFEM during the last years, and the resolution of the practical exercises presented by the author in his book.
The author
Author's Note: Every problem in the design of the book can be communicated to the author for his address, Rua Augusto Lessa 268 4200-097 Porto, Portugal; the author`s e-mail is eepv@yahoo.com
[1]Extract of text adapted from EE Times by Korne Vennema, Market Applications Engineer, Philips Discrete Semiconductors, Mansfield, Mass.