DOCSLIB.ORG

Electrical Properties of Materials.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electrical Properties of Materials.Pdf Electrical Properties Of Materials, Seventh Edition by L. Solymar and D. Walsh Oxford University Press © 2004 (414 pages) ISBN:0199267936 Written in an informal, accessible style, this core text presents the simplest model that can display the essential properties of a phenomenon and examines it, showing the difference between ideal and actual behavior. Table of Contents Electrical Properties of Materials, Seventh Edition Preface to the Seventh Edition Introduction Chapter 1 - The Electron as a Particle Chapter 2 - The Electron as a Wave Chapter 3 - The Electron Chapter 4 - The Hydrogen Atom and the Periodic Table Chapter 5 - Bonds Chapter 6 - The Free Electron Theory of Metals Chapter 7 - The Band Theory of Solids Chapter 8 - Semiconductors Chapter 9 - Principles of Semiconductor Devices Chapter 10 - Dielectric Materials Chapter 11 - Magnetic Materials Chapter 12 - Lasers Chapter 13 - Optoelectronics Chapter 14 - Superconductivity Epilogue Appendix I - Organic Semiconductors Appendix II - Artificial Materials Appendix III - Physical Constants Appendix IV - Variational Calculus. Derivation of Euler's Equation Appendix V - Suggestions for Further Reading Answers to Exercises Index List of Figures List of Tables Electrical Properties of Materials, Seventh Edition L. Solymar and D. Walsh Department of Engineering Science University of Oxford OXFORD UNIVERSITY PRESS Great Clarendon Street, Oxford OX2 6DP Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide in Oxford New York Auckland Bangkok Buenos Aires Cape Town Chennai Dares Salaam Delhi Hong Kong Istanbul Karachi Kolkata Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi São Paulo Shanghai Taipei Tokyo Toronto Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Published in the United States by Oxford University Press Inc., New York © Oxford University Press, 1970, 1979, 1984, 1988, 1993, 1998, 2004 First edition 1970 Second edition 1979 Third edition 1984 Fourth edition 1988 Fifth edition 1993 Sixth edition 1998, reprinted 1999 Seventh edition 2004 The moral rights of the author have been asserted Database right Oxford University Press (maker) All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose this same condition on any acquirer A catalogue record for this title is available from the British Library Library of Congress Cataloging in Publication Data (Data available) ISBN 0 19 9267936 Typeset by Newgen Imaging Systems (P) Ltd, Chennai, India Printed in Great Britain by Antony Rowe Ltd, Chippenham Preface to the Seventh Edition We have taken the opportunity of a new edition to include some subjects which reached maturity in the last 5 years, like organic semiconductors and artificial materials. Other additions are mainly in the device field. We have added microelectromechanical systems (MEMS), integrated circuits growing in the third dimension, expanded considerably nanoelectronics heralding the advent of radically new devices still at the laboratory stage like nanotube transistors, single electron transistors, and organic transistors. We added quantum wires, quantum dots, and the quantum cascade laser to the section on semiconductor lasers, introduced a new set of magnetic devices, whose operation is based on electron spin, under the heading of spintronics, added a new ferroelectric random access memory to the dielectric chapter and described a very fast new memory in the superconductivity chapter. We can claim sustained progress on all fronts. A possible exception is the theory of superconducting mechanisms that continues to exasperate the experts. The biggest change has probably occurred in the field of lighting with remarkable advances in light emitting diodes based on GaN and with the surprising emergence of organic molecular devices glowing brightly. It can be argued that the tungsten filament electric light, invented by Swan and Edison in 1861 and 1879, did more to improve the lives of people than most inventions (oil lamps were very tedious-Second World War experience). The basic technology was similar to thermionic valves, which came later and have long since almost vanished. So is it time for solid state electronics to take over with more efficient lighting, reduce greenhouse emissions and perhaps save the planet? We hope so. In preparing this edition, we again benefited from comments received from students and lecturers. We are grateful to Professor Tung Hsu of the National Tsinghua University who called our attention to a mistake that has been there since the first edition. Our thanks are due to Richard Syms who not only introduced us to a subject we knew little about but also provided us with a draft version of the sections on MEMS and on its application in optical switching. We are indebted to Hisashi Masui for the anthropomorphic analogy of the vander Waals bond. We also wish to acknowledge the help we received from Harry Anderson, Kristel Fobelets, and Paul Stavrinou in the fields of organic semiconductors, semiconductor devices, and lasers, respectively. And thanks to Steffi Friedrichs for help with nanotubes. L.S. D.W Oxford May 2003 Introduction Till now man has been up against Nature; from now on he will be up against his own nature. Dennis Gabor Inventing the future It is a good thing for an uneducated man to read books of quotations. W.S. Churchill Roving commission in my early life (1930) Engineering used to be a down-to-earth profession. The Roman engineers, who provided civilized Europe with bridges and roads, did a job comprehensible to all. And this is still true in most branches of engineering today. Bridge-building has become a sophisticated science, the mathematics of optimum structures is formidable; nevertheless, the basic relationships are not far removed from common sense. A heavier load is more likely to cause a bridge to collapse, and the use of steel instead of wood will improve the load-carrying capacity. Solid-state electronic devices are in a different category. In order to understand their behaviour, you need to delve into quantum mechanics. Is quantum mechanics far removed from common sense? Yes, for the time being, it is. We live in a classical world. The phenomena we meet every day are classical phenomena. The fine details represented by quantum mechanics are averaged out; we have no first-hand experience of the laws of quantum mechanics; we can only infer the existence of certain relationships from the final outcome. Will it be always this way? Not necessarily. There are quantum phenomena known to exist on a macroscopic scale as, for example, superconductivity, and it is quite likely that certain biological processes will be found to represent macroscopic quantum phenomena. So, a ten-year-old might be able to give a summary of the laws of quantum mechanics—half a century hence. For the time being there is no easy way to quantum mechanics; no short cuts and no broad highways. We just have to struggle through. I believe it will be worth the effort. It will be your first opportunity to glance behind the scenes, to pierce the surface and find the grandiose logic of a hidden world. Should engineers be interested at all in hidden mysteries? Isn't that the duty and privilege of the physicists? I do not think so. If you want to invent new electronic devices, you must be able to understand the operation of the existing ones. And perhaps you need to more than merely understand the physical mechanism. You need to grow familiar with the world of atoms and electrons, to feel at home among them, to appreciate their habits and characters. We shall not be able to go very deeply into the subject. Time is short, and few of you will have the mathematical apparatus for the frontal assault. So we shall approach the subject in carefully planned steps. First, we shall try to deduce as much information as possible on the basis of the classical picture. Then, we shall talk about a number of phenomena that are clearly in contrast with classical ideas and introduce quantum mechanics, starting with Schrödinger's equation. You will become acquainted with the properties of individual atoms and what happens when they conglomerate and take the form of a solid. You will hear about conductors, insulators, semiconductors, p-n junctions, transistors, lasers, superconductors, and a number of related solid-state devices. Sometimes the statement will be purely qualitative but in most cases we shall try to give the essential quantitative relationships. These lectures will not make you an expert in quantum mechanics nor will they enable you to design a computer the size of a matchbox. They will give you no more than a general idea. If you elect to specialize in solid-state devices you will, no doubt, delve more deeply into the intricacies of the theory and into the details of the technology. If you should work in a related subject then, presumably, you will keep alive your interest, and you may occasionally find it useful to be able to think in quantum-mechanical terms. If your branch of engineering has nothing to do with quantum mechanics, would you be able to claim in ten years' time that you profited from this course? I hope the answer to this question is yes. I believe that once you have been exposed (however superficially) to quantum-mechanical reasoning, it will leave permanent marks on you.
Load more

Recommended publications
  • Junction Analysis and Temperature Effects in Semi-Conductor
    Junction analysis and temperature effects in semi-conductor heterojunctions by Naresh Tandan A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Electrical Engineering Montana State University © Copyright by Naresh Tandan (1974) Abstract: A new classification for semiconductor heterojunctions has been formulated by considering the different mutual positions of conduction-band and valence-band edges. To the nine different classes of semiconductor heterojunction thus obtained, effects of different work functions, different effective masses of carriers and types of semiconductors are incorporated in the classification. General expressions for the built-in voltages in thermal equilibrium have been obtained considering only nondegenerate semiconductors. Built-in voltage at the heterojunction is analyzed. The approximate distribution of carriers near the boundary plane of an abrupt n-p heterojunction in equilibrium is plotted. In the case of a p-n heterojunction, considering diffusion of impurities from one semiconductor to the other, a practical model is proposed and analyzed. The effect of temperature on built-in voltage leads to the conclusion that built-in voltage in a heterojunction can change its sign, in some cases twice, with the choice of an appropriate doping level. The total change of energy discontinuities (&ΔEc + ΔEv) with increasing temperature has been studied, and it is found that this change depends on an empirical constant and the 0°K Debye temperature of the two semiconductors. The total change of energy discontinuity can increase or decrease with the temperature. Intrinsic semiconductor-heterojunction devices are studied? band gaps of value less than 0.7 eV.
    [Show full text]
  • Introduction to Semiconductor
    Introduction to semiconductor Semiconductors: A semiconductor material is one whose electrical properties lie in between those of insulators and good conductors. Examples are: germanium and silicon. In terms of energy bands, semiconductors can be defined as those materials which have almost an empty conduction band and almost filled valence band with a very narrow energy gap (of the order of 1 eV) separating the two. Types of Semiconductors: Semiconductor may be classified as under: a. Intrinsic Semiconductors An intrinsic semiconductor is one which is made of the semiconductor material in its extremely pure form. Examples of such semiconductors are: pure germanium and silicon which have forbidden energy gaps of 0.72 eV and 1.1 eV respectively. The energy gap is so small that even at ordinary room temperature; there are many electrons which possess sufficient energy to jump across the small energy gap between the valence and the conduction bands. 1 Alternatively, an intrinsic semiconductor may be defined as one in which the number of conduction electrons is equal to the number of holes. Schematic energy band diagram of an intrinsic semiconductor at room temperature is shown in Fig. below. b. Extrinsic Semiconductors: Those intrinsic semiconductors to which some suitable impurity or doping agent or doping has been added in extremely small amounts (about 1 part in 108) are called extrinsic or impurity semiconductors. Depending on the type of doping material used, extrinsic semiconductors can be sub-divided into two classes: (i) N-type semiconductors and (ii) P-type semiconductors. 2 (i) N-type Extrinsic Semiconductor: This type of semiconductor is obtained when a pentavalent material like antimonty (Sb) is added to pure germanium crystal.
    [Show full text]
  • XI. Band Theory and Semiconductors I
    XI. ELECTRONIC PROPERTIES (DRAFT) 11.1 THE ALLOWED ENERGIES OF ELECTRONS Over the next few weeks we are going to explore the electrical properties of materials. Our starting point for this investigation is simply to ask the question, “Why do some materials conduct electricity and others don’t?” It should come as no surprise that the answer to this question can be found in structure, in this case the structure of the electrons density, which in turn is related to the electron energies and how these may change when a material is subjected to an electrical potential difference, i.e., hooked up to a battery. Up until the early part of the twentieth century it was thought that electrons obeyed the laws of classical mechanics, and, just like everything we could observe at that time, an electron could be made to move in a way that it would take on any energy we wished. For example, if we want a ball with the mass of 0.25 kg to have a kinetic energy of 0.5 J, all we need do is accelerate it to exactly 2 m/sec. If we want its kinetic energy to be 0.501 J, then we need to accelerate it to 2.001999 m/sec. If we want it to have a kinetic energy of X, it must have a velocity of exactly (8X)1/2. According to the principles of classical mechanics, there is nothing that prevents us from doing this. However, it turns out that these principles are not quite right, under some circumstances the ball cannot be made to take on any energy we desire, it can only possess specific energies, which we often denote with a subscript, En.
    [Show full text]
  • Development of Metal Oxide Solar Cells Through Numerical Modelling
    Development of Metal Oxide Solar Cells through Numerical Modelling Le Zhu Doctor of Philosophy awarded by The University of Bolton August, 2012 Institute for Renewable Energy and Environment Technologies, University of Bolton Acknowledgements I would like to acknowledge Professor Jikui (Jack) Luo and Professor Guosheng Shao for the professional and patient guidance during the whole research. I would also like to thank the kind help by and the academic discussion with the members of solar cell group and other colleagues in the department, Mr. Liu Lu, Dr. Xiaoping Han, Dr. Xiaohong Xia, Mr. Yonglong Shen, Miss. Quanrong Deng and Mr. Muhammad Faruq. I would also like to acknowledge the financial support from the Technology Strategy Board under the grant number TP11/LCE/6/I/AE142J. For my beloved parents Thank you for your love and support. I Abstract Photovoltaic (PV) devices become increasingly important due to the foreseeable energy crisis, limitation in natural fossil fuel resources and associated green-house effect caused by carbon consumption. At present, silicon-based solar cells dominate the photovoltaic market owing to the well-established microelectronics industry which provides high quality Si-materials and reliable fabrication processes. However ever- increased demand for photovoltaic devices with better energy conversion efficiency at low cost drives researchers round the world to search for cheaper materials, low-cost processing, and thinner or more efficient device structures. Therefore, new materials and structures are desired to improve the performance/price ratio to make it more competitive to traditional energy. Metal Oxide (MO) semiconductors are one group of the new low cost materials with great potential for PV application due to their abundance and wide selections of properties.
    [Show full text]
  • Msc Thesis Optimization of Heterojunction C-Si Solar Cells with Front Junction Architecture
    Delft University of Technology Faculty of Electrical Engineering, Mathematics and Computer Science Optimization of heterojunction c-Si solar cells with front junction architecture by Camilla Massacesi MSc Thesis Optimization of heterojunction c-Si solar cells with front junction architecture by Camilla Massacesi to obtain the degree of Master of Science in Sustainable Energy Technology at the Delft University of Technology, to be defended publicly on Thursday October 5, 2017 at 9:30 AM. Student number: 4512308 Project duration: October 25, 2016 – October 5, 2017 Supervisors: Dr. O. Isabella, Dr. G. Yang Assessment Committee: Prof. dr. M. Zeman, Dr. M. Mastrangeli, Dr. O. Isabella, Dr. G. Yang I know I will always burn to be The one who seeks so I may find The more I search, the more my need Time was never on my side So you remind me what left this outlaw torn. Abstract Wafer-based crystalline silicon (c-Si) solar cells currently dominate the photovoltaic (PV) market with high-thermal budget (T > 700 ∘퐶) architectures (e.g. i-PERC and PERT). However, also low-thermal (T < 250 ∘퐶) budget heterojunction architecture holds the potential to become mainstream owing to the achievable high efficiency and the relatively simple lithography-free process. A typical heterojunction c-Si solar cell is indeed based on textured n-type and high bulk lifetime wafer. Its front and rear sides are passivated with less than 10-푛푚 thick intrinsic (i) hydrogenated amorphous silicon (a-Si:H) and front and rear side coated with less than 10-푛푚 thick doped a-Si:H layers.
    [Show full text]
  • CHAPTER 1: Semiconductor Materials & Physics
    Chapter 1 1 CHAPTER 1: Semiconductor Materials & Physics In this chapter, the basic properties of semiconductors and microelectronic devices are discussed. 1.1 Semiconductor Materials Solid-state materials can be categorized into three classes - insulators, semiconductors, and conductors. As shown in Figure 1.1, the resistivity of semiconductors, ρ, is typically between 10-2 and 108 Ω-cm. The portion of the periodic table related to semiconductors is depicted in Table 1.1. Figure 1.1: Typical range of conductivities for insulators, semiconductors, and conductors. Semiconductors can be composed of a single element such as silicon and germanium or consist of two or more elements for compound semiconductors. A binary III-V semiconductor is one comprising one element from Column III (such as gallium) and another element from Column V (for instance, arsenic). The common element and compound semiconductors are displayed in Table 1.2. City University of Hong Kong Chapter 1 2 Table 1.1: Portion of the Periodic Table Related to Semiconductors. Period Column II III IV V VI 2 B C N Boron Carbon Nitrogen 3 Mg Al Si P S Magnesium Aluminum Silicon Phosphorus Sulfur 4 Zn Ga Ge As Se Zinc Gallium Germanium Arsenic Selenium 5 Cd In Sn Sb Te Cadmium Indium Tin Antimony Tellurium 6 Hg Pd Mercury Lead Table 1.2: Element and compound semiconductors. Elements IV-IV III-V II-VI IV-VI Compounds Compounds Compounds Compounds Si SiC AlAs CdS PbS Ge AlSb CdSe PbTe BN CdTe GaAs ZnS GaP ZnSe GaSb ZnTe InAs InP InSb City University of Hong Kong Chapter 1 3 1.2 Crystal Structure Most semiconductor materials are single crystals.
    [Show full text]
  • High Performance N-Type Polymer Semiconductors for Printed Logic
    High Performance n-Type Polymer Semiconductors for Printed Logic Circuits by Bin Sun A thesis presented at University of Waterloo in fulfillment of the thesis requirement for the degree of Doctoral of Philosophy in Chemical Engineering Waterloo, Ontario, Canada, 2016 © Bin Sun 2016 Author’s Declaration I hereby declare that this thesis consists of materials all of which I authored or co-authored: see Statement of Contributions included in the thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Statement of Contribution This thesis contains materials from several published or submitted papers, some of which resulted from collaboration with my colleagues in the group. The content in Chapter 2 has been partially published in Adv. Mater. 2014, 26, 2636. B. Sun, W. Hong, Z. Yan, H. Aziz, Y. Li The content in Chapter 3 has been partially published in Polym. Chem. 2015, 6, 938. B. Sun, W. Hong, H. Aziz, Y. Li The content in Chapter 4 has been partially published in Org. Electron. 2014, 15, 3787. B. Sun, W. Hong, E. Thibau, H. Aziz, Z. Lu, Y. Li The content in Chapter 5 has been partially published in ACS Appl Mater Interfaces 2015, 7, 18662. B. Sun, W. Hong, E. Thibau, H. Aziz, Z. Lu, Y. Li, iii Abstract Solution processable polymer semiconductors open up potential applications for radio-frequency identification (RFID) tags, flexible displays, electronic paper and organic memory due to their low cost, large area processability, flexibility and good mechanical properties.
    [Show full text]
  • Semiconductor Science and Leds
    Optoelectronics EE/OPE 451, OPT 444 Fall 2009 Section 1: T/Th 9:30- 10:55 PM John D. Williams, Ph.D. Department of Electrical and Computer Engineering 406 Optics Building - UAHuntsville, Huntsville, AL 35899 Ph. (256) 824-2898 email: [email protected] Office Hours: Tues/Thurs 2-3PM JDW, ECE Fall 2009 SEMICONDUCTOR SCIENCE AND LIGHT EMITTING DIODES • 3.1 Semiconductor Concepts and Energy Bands – A. Energy Band Diagrams – B. Semiconductor Statistics – C. Extrinsic Semiconductors – D. Compensation Doping – E. Degenerate and Nondegenerate Semiconductors – F. Energy Band Diagrams in an Applied Field • 3.2 Direct and Indirect Bandgap Semiconductors: E-k Diagrams • 3.3 pn Junction Principles – A. Open Circuit – B. Forward Bias – C. Reverse Bias – D. Depletion Layer Capacitance – E. Recombination Lifetime • 3.4 The pn Junction Band Diagram – A. Open Circuit – B. Forward and Reverse Bias • 3.5 Light Emitting Diodes – A. Principles – B. Device Structures • 3.6 LED Materials • 3.7 Heterojunction High Intensity LEDs Prentice-Hall Inc. • 3.8 LED Characteristics © 2001 S.O. Kasap • 3.9 LEDs for Optical Fiber Communications ISBN: 0-201-61087-6 • Chapter 3 Homework Problems: 1-11 http://photonics.usask.ca/ Energy Band Diagrams • Quantization of the atom • Lone atoms act like infinite potential wells in which bound electrons oscillate within allowed states at particular well defined energies • The Schrödinger equation is used to define these allowed energy states 2 2m e E V (x) 0 x2 E = energy, V = potential energy • Solutions are in the form of
    [Show full text]
  • Metals, Semiconductors, and Insulators Every Solid Has Its Own Characteristic Energy Band Structure
    Metals, Semiconductors, and Insulators Every solid has its own characteristic energy band structure. In order for a material to be conductive, both free electrons and empty states must be available. Metals have free electrons and partially filled valence bands, therefore they are highly conductive (a). Semimetals have their highest band filled. This filled band, however, overlaps with the next higher band, therefore they are conductive but with slightly higher resistivity than normal metals (b). Examples: arsenic, bismuth, and antimony. Insulators have filled valence bands and empty conduction bands, separated by a large band gap Eg(typically >4eV), they have high resistivity (c ). Semiconductors have similar band structure as insulators but with a much smaller band gap. Some electrons can jump to the empty conduction band by thermal or optical excitation (d). Eg=1.1 eV for Si, 0.67 eV for Ge and 1.43 eV for GaAs Conduction in Terms of Band Metals An energy band is a range of allowed electron energies. The energy band in a metal is only partially filled with electrons. Metals have overlapping valence and conduction bands Drude Model of Electrical Conduction in Metals Conduction of electrons in metals – A Classical Approach: In the absence of an applied electric field (ξ) the electrons move in random directions colliding with random impurities and/or lattice imperfections in the crystal arising from thermal motion of ions about their equilibrium positions. The frequency of electron-lattice imperfection collisions can be described by a mean free path λ -- the average distance an electron travels between collisions. When an electric field is applied the electron drift (on average) in the direction opposite to that of the field with drift velocity v The drift velocity is much less than the effective instantaneous speed (v) of the random motion −2 − 1 8− 1 1 2 3 In copperv ≈ 10 cm.
    [Show full text]
  • A Study of Processing of Indium Doped Semiconductor Material
    A Study of Processing of Indium Doped Semiconductor Material. A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Technology In Metallurgical and Materials Engineering Submitted by Rama Chandra Sarangi Roll No. 211MM1369 Department of Metallurgical & Materials Engineering National Institute of Technology Rourkela 2011-2013 Acknowledgement I express my sincere gratitude to Dr. S. C.Mishra(Prof.) and Dr. S. Sarkar (Assistant Professor) of the Department of Metallurgical and Material Engineering, National Institute of Technology, Rourkela, for giving me this great opportunity to work under his guidance. I am also thankful to him for his valuable suggestions and constructive criticism which has helped me in the development of this work. I am also thankful to his optimistic nature which has helped this project to come a long way through. I am sincerely thankful to Prof. B. C. Ray, Professor and Head of Metallurgical and Materials Engineering Department for providing me necessary facility for my work. I express my sincere thanks to Prof A. K. mondal, the M.Tech Project co-ordinators of Metallurgical & Materials Engineering department. Special thanks to my family members always encouraging me for higher studies, all department members specially Mr. Rajesh, Lab assistant of SEM lab and Mr. Sahoo, Lab assistant of Material Science lab all my friends of department of Metallurgical and Materials Engineering for being so supportive and helpful in every possible way. RAMACHANDRASARANGI Roll No. : 211MM1369 CONTENTS Title Page No. Certificate i Acknowledgement ii Abstract iii Contents iv List of figures vii 1. INTRODUCTION 1 1.1 Resistance and its origin 1 1.1.1 Causes of resistance 1 1.1.2Temperaturedependenceofresistance 2 1.2 Resistivity 2 1.3 Material Description 4 1.4 Objective 6 2.
    [Show full text]
  • Lecture 7: Extrinsic Semiconductors - Fermi Level
    Lecture 7: Extrinsic semiconductors - Fermi level Contents 1 Dopant materials 1 2 EF in extrinsic semiconductors 5 3 Temperature dependence of carrier concentration 6 3.1 Low temperature regime (T < Ts)................7 3.2 Medium temperature regime (Ts < T < Ti)...........8 1 Dopant materials Typical doping concentrations in semiconductors are in ppm (10−6) and ppb (10−9). This small addition of `impurities' can cause orders of magnitude increase in conductivity. The impurity has to be of the right kind. For Si, n-type impurities are P, As, and Sb while p-type impurities are B, Al, Ga, and In. These form energy states close to the conduction and valence band and the ionization energies are a few tens of meV . Ge lies the same group IV as Si so that these elements are also used as impurities for Ge. The ionization energy data n-type impurities for Si and Ge are summarized in table 1. The ionization energy data for p-type impurities for Si and Ge is summarized in table 2. The dopant ionization energies for Ge are lower than Si. Ge has a lower band gap (0.67 eV ) compared to Si (1.10 eV ). Also, the Table 1: Ionization energies in meV for n-type impurities for Si and Ge. Typical values are close to room temperature thermal energy. Material P As Sb Si 45 54 39 Ge 12 12.7 9.6 1 MM5017: Electronic materials, devices, and fabrication Table 2: Ionization energies in meV for p-type impurities. Typical values are comparable to room temperature thermal energy.
    [Show full text]
  • Ferroelectric-Semiconductor Systems for New Generation of Solar Cells
    University of New Orleans ScholarWorks@UNO University of New Orleans Theses and Dissertations Dissertations and Theses Spring 5-19-2017 Ferroelectric-Semiconductor Systems for New Generation of Solar Cells Rahmatollah Eskandari University of New Orleans, New Orleans, [email protected] Follow this and additional works at: https://scholarworks.uno.edu/td Part of the Semiconductor and Optical Materials Commons Recommended Citation Eskandari, Rahmatollah, "Ferroelectric-Semiconductor Systems for New Generation of Solar Cells" (2017). University of New Orleans Theses and Dissertations. 2318. https://scholarworks.uno.edu/td/2318 This Dissertation is protected by copyright and/or related rights. It has been brought to you by ScholarWorks@UNO with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Dissertation has been accepted for inclusion in University of New Orleans Theses and Dissertations by an authorized administrator of ScholarWorks@UNO. For more information, please contact [email protected]. Ferroelectric-Semiconductor Systems for New Generation of Solar Cells A Dissertation Submitted to the Graduate Faculty of the University of New Orleans in partial fulfillment of the requirement for the degree of Doctor of Philosophy in Engineering and Applied Science (Physics) by Rahmatollah Eskandari M.Sc. University of Tabriz, Iran, 2006 B.Sc. Amirkabir University of Technology, Iran, 2002 May, 2017 Copyright 2017 Rahmatollah Eskandari ii To: My Family iii Acknowledgement I would like to express my heartfelt gratitude and appreciation to my advisor Prof.
    [Show full text]