Semi-Conductors insulators semi-conductors N-type Semi-Conductors P-type Semi-Conductors
|
|
- Bernadette Cummings
- 6 years ago
- Views:
Transcription
1 Semi-Conductors In the metal materials considered earlier, the coupling of the atoms together to form the material decouples an electron from each atom setting it free to roam around inside the material. These free electrons can easily be made to move by an applied electric field enabling electric currents to flow through the material. It is the large number of these electrons in metals that make them good conductors; without them electrons would flow much less easily through them. This can be seen in 2 other groups of materials: insulators: have very few free electrons in the material, because electrons are strongly bound to the atoms of the material. Pulling electrons out of the material or pushing them in, is extremely difficult. Electrons do not flow in larger numbers through the material in response to an electric field. The resistor of the material is effectively infinite, R. [The quantum explanation is rather more complex, but the result is the same: insulators are extremely poor conductors.] semi-conductors: are neither insulators nor good conductors. The outer electron of each atom in the semi-conductor is weakly bound to the atoms; some outer electrons are set free to move about the material, but most are bound to atoms. Thus, there are some free electrons in the material but only enough to make it weakly conducting. We shall not examine insulators further, but semi-conductors are of great importance because their conductivity can be improved to produce 2 different types of conducting material. These forms can be used together to produce diodes and transistors: electrical devices of particular, importance and interest. The conductivity of semi-conductors is enhanced by embedding atoms of another material into the semi-conductor. This is called `doping. There are 2 types of dopant: donor and acceptor materials. The best known semi-conductor is silicon, but there are others e.g. germanium, diamond, siliconcarbide. N-type Semi-Conductors are produced when donor atoms are embedded in a semi-conductor, outer electrons from donor atoms are set free to move through the material. This increases the conductivity of the material. Because the number of free electrons in the semi-conductor is quite low, it does not need much donor material to increase the conductivity significantly (see box). N-type materials are like metals in that there are lots of free electrons. Phosphorus is a donor material that is used with silicon. Let s assume that there are atoms /m 3 in the semi-conductor material, and that 1 in atoms release an electron into the material. Then there are electrons /m 3. Adding 1 donor atom for every 10 6 atoms (0.0001%), gives donor atoms/m 3 and electrons/m 3, assuming each donor atom gives up an electron: the number of free electrons, and thus the conductivity, has increased by times. In practice only a fraction of the donor atoms give up an electron, and the conductivity increases much more slowly. In silicon, adding 1 donor atom for every 10 5 silicon atoms increases conductivity by P-type Semi-Conductors are produced when acceptor atoms are embedded in a semi-conductor. An acceptor atom easily captures an extra electron and binds it firmly, becoming negatively charged. When acceptors atoms are embedded in a semi-conductor, some of them attract and bind an extra electron. Once all the free electrons in the material have been bound, electrons are pulled off their surrounding semi-conductor atoms: this is quite easy as their outer electron is only weakly bound. This process leaves a large number of semi-conductor atoms with a positive charge (roughly equal to the number of acceptor atoms with a negative charge). It is quite easy for such a positively charged atom to pull the outer electron off a neighbouring neutral semi-conductor atom, swapping the charge. It is usual to label the positively charged atom a hole (a place where an electron can go), and to speak of the hole moving. In a P-type semi-conductor, this movement of an electron from an atom to a hole occurs frequently and the holes move around rapidly: in silicon, the hole mobility in p-type material is about 1/2 that of the electrons in n-type material. 12
2 If only sufficient acceptor atoms are embedded to remove the free electrons, the material becomes an insulator. Adding further acceptor atoms creates a hole for each embedded atom, and the holes created can be used to carry an electric current. Applying a voltage across a p-type semi-conductor leads to electrons being pulled out at one end of the material and being pushed in at the other; electrons move through the material via the holes. However, it is more convenient to think of the positively charged holes moving through the material from the higher voltage to the lower: holes are ejected into the material at the high voltage end (an electron is pulled off an atom creating a hole); at the low voltage end holes are pulled out of the material (electrons are injected into the material and coalesce with the arriving holes). A simple analogy for this flow of holes is a queue of people waiting on a row of chairs outside an office. When the person at the head of the queue goes into the office, an empty seat, a hole, is created at the head of the queue. When the next person in the queue moves chair into the vacant chair, the hole moves in the opposite direction. This continues as the remainder of the queue shifts along, until the hole reaches the end of the queue, when it is disappears as another person arrives and sits down. The hole is injected at the head of the queue, flows to the tail of the queue and is removed. The greater the hole density the higher the conductivity of the material, so that the quantity of embedded acceptor atoms controls the conductivity, and a small percentage of acceptor material causes a very much larger increase in conductivity. For silicon, Boron is the usual acceptor element. Semi-Conductor Diode The figure shows a semi-conductor diode. The material has abutting n-type and p-type material and a narrow region where the 2 materials merge: this is the p-n junction. This has unique electrical properties. Electrons can be made to flow easily from the n-type region into the p-type region, and for holes to flow in the other direction. It is very much more difficult to get the opposite flows. For low voltage drops across the junction, the diode has very low resistance, R 0, in one direction, but very high resistance, R, in the other direction. A full explanation of this is too complex for here. It can be considered that it is easy to move electrons from the n-type into the p-type region because there are lots of free electrons in the n-type region; it is much more difficult to remove an electron from the p-type region because there are no free electrons. A similar argument may be made for the holes. When the p-region connects to a higher voltage source and the n-region to lower voltage source, a current flows and the p-n junction is said to have a forward-bias or to be forward-biased. When the voltage connections are reversed (n-type more positive than the p-type region), no current flows and the junction is said to have a reverse-biasi or to be reverse-biased. The width of the transition region between n-type and p-type can be very narrow, much less than 1 micron (10-6 m). Diodes are useful devices in their own right, e.g. in turning alternating current into direct current. The p-n junction is fundamental to the operation of the transistor. Transistor The transistor like the diode is made from abutting regions of n-type and p-type semi-conductor material, but the transistor has one material type sandwiched between the other type so that there are 2 p-n junctions. There are 2 possibilities: the p-n-p transistor with n-type material sandwiched between p-type material; the n-p-n transistor with p-type material sandwiched between n-type. There are a 13
3 variety of transistors structures and modes of control/operation. We examine one type, the so-called MOSFET (Metal-Oxide-Silicon Field Effect Transistor), in both n-p-n and p-n-p forms and the operation of these as voltage-controlled switches. n-p-n transistor (MOSFET) The diagram shows a silicon n-p-n field effect transistor. It is built on the surface of a wafer of p-type material about 1 mm thick: this is called the substrate. The transistor is formed by producing 2 n-type regions in the surface layer. These n-regions with the p- region in-between form the n- p-n sandwich. Above the middle of the sandwich, a region of silicon-oxide, an insulator, is formed, and above this is placed a layer of conducting material, called the Gate. The remaining parts of the diagram are metal regions attached to the n-type regions as connecting wires, and a connection of the substrate to the low voltage terminal of the power supply. The Gate used to be made of metal, thus giving the phrase Metal-Oxide-Silicon from the arrangement of Gate, insulator and the substrate. Nowadays, the Gate is made from a form of silicon that is a good conductor. This is poly-crystalline silicon, which has very many different crystalline regions with many boundaries between crystals. At these boundaries many free electrons are released by silicon atoms to give a large enough free electron density in the material for a reasonable conductivity. [The substrate is itself cut from a single crystal of silicon, i.e. it has a uniform crystal structure with no crystal boundaries]. With modern manufacturing techniques, the n-type regions are of the order of 0.25 microns wide and deep, and a similar distance apart. These dimensions are continuously being reduced as technology improves, and dimensions of 0.15 microns and smaller can be produced by a few manufacturers. The explanation of the operation of this transistor as a simple switch requires its attachment to a power supply. For further examples we assume a 5V power supply since this is the traditional voltage used in digital circuits (many circuits now use 3.3V or a mixture of 3.3V and 5V supplies). To show the operation of the n-p-n transistor, the low voltage power supply terminal, 0 Volt, is directly connected to one of the n-type regions. Whichever region is chosen is labelled the Source: the name reflects the fact this region will be the source of electrons when a current flows through the transistor. The other n-type region will be connected indirectly to the positive, 5 Volt, terminal of the power supply though other devices that will act to reduce the current flow when the transistor is conducting, as otherwise a short-circuit condition will exist. This n-type region is labelled the Drain, as it is the terminal into which electrons flow when the transistor conducts. The voltage on this region will be controlled by the operation of the transistor and may be 0V or 5V, i.e. it is greater than or equal to the substrate voltage. The switching action between the Source and Drain regions is under the control of the Gate: this is the switch control input of the transistor with the voltage on the Gate, either 0 or 5 volts, deciding the state of the switch as either conducting or non-conducting. 14
4 Gate at 0 Volts - switch non-conducting: Assuming that there is no current between the n-regions then all the voltage from the power supply will appear across the p-region of the sandwich, and the Source will be at 0V and the drain at 5V: this is the result that we saw in Circuit 2 of page 9 of the Basic Electricity notes. Examining the Source-Substrate junction, both the source and the substrate are at 0 Volts, so that there is no voltage drop to drive a current between Source and Substrate. Turning to the Drain-Substrate junction, this is a p-n junction with the p-region, the Substrate at 0V, and the n-region, the Drain is at 5V, so that the junction is reverse-biased and no current can flow through the junction. Since no current can flow into or out of the Gate, because of the insulator, there are no current flows anywhere within the transistor, confirming the assumption with which we started. Gate at 5 Volts - switch conducting: What difference does changing the voltage on the Gate to 5V? This introduces an electric field across the insulator: with 5V on the Gate, 0V on the substrate, and an insulator thickness of 1 micron, the electric field strength is 5 million Volts/metre - enough to make your hair stand on end. This electric field reaches down into the substrate below and pulls electrons towards the surface of the substrate into the channel region below the insulator: the figures shows the channel growing. Electrons move into the channel region until there are sufficient excess electrons to screen the substrate below the channel from the electric field. The channel region is now rich in free electrons and is now no longer a p-type region, but is an n-type region. There is now no reverse-biased p-n junction to stop current flowing nor is there an n-p-n sandwich: just one n-region through which current can flow. In the figure right the Drain voltage has changed since with the current flow through the switch the voltage drop from the power supply will appear across some more resistive part of the circuit. An alternative way to look at this operation is that at the moment the electric field appears across the insulator, the voltage of the region below the insulator instantaneously becomes 5V; this voltage forward-biases the Channel-Source p-n junction and pulls electrons out of the Source into the channel; these electrons move across the channel to the Drain, filling the channel and reducing the voltage on the channel to 0V. While the Gate stays at 5V the channel remains in place. Switching Gate voltage from 5V to 0V: When the Gate is set back to 0V, the electric field disappears and there is nothing to hold the electrons in the n-region. They are rapidly absorbed into the Drain and Source regions. Another way of looking at this is that at the change of voltage of the gate, the voltage on the channel also immediately drops by 5 Volts to -5V (the channel has an excess of negative charge with respect to the surrounding 0V regions, i.e. is more negative) and the surrounding regions at 0V suck the electrons from the channel. The n-p-n transistor is commonly called an n-type transistor, because in its conducting phase it becomes all n-type material. Its standard logic symbol is shown right in 2 forms: one form shows the connection from the substrate to the 0V power supply connection, while the other leaves this out. The symbols highlight the isolation of the gate input from the drain and source terminals through the gap between the gate input and the drain-source line. 15
5 p-n-p MOSFET transistor The p-n-p transistor is very similar in operation to the n-p-n transistor, but there are important differences; the major one being that the Gate voltage for conduction is 0V opposite to that for the n-p-n. The figure shows the layout of a p-n-p transistor. It can be seen that the n-type and p-type regions are reversed from the n-p-n transistor: there is now an n-type substrate with p-type Source and Drain regions. The substrate is attached to the 5V power supply terminal. In order to illustrate the operation of the p-n-p transistor, different power supply connections are used: the Drain region is directly connected to the 5V power supply terminal, while the Source is connected indirectly to the 0V supply terminal via other circuit elements that restrict current flow when the transistor is conducting. The voltage of the source is controlled by the switching action of the transistor: it is 0V or 5V. Gate at 5 Volts - switch non-conducting: Assuming that there is no current between the p- regions then all the voltage from the power supply will appear across the n-region of the sandwich, and the Source will be at 0V and the drain at 5V. Examining the Drain-Substrate junction, both the substrate and the drain are at 5 Volts, so that there is no voltage drop to drive a current between them. Turning to the Source-Substrate junction, this is a p-n junction with the n-region, the Substrate at 5V, and the p-region, the Source is at 0V, so that the junction is reverse-biased and no current can flow through the junction. Since no current can flow into or out of the Gate, because of the insulator, there are no current flows anywhere within the transistor, confirming the initial assumption. Gate at 0 Volts - switch conducting: There is now an electric field across the insulator: with 0V on the Gate, 5V on the substrate. This electric field reaches down into the substrate below, pushing electrons away and creating holes in the channel region: the figures shows the channel growing. Holes move into the channel region until there are sufficient excess holes to screen the substrate below the channel from the electric field. The channel region is now rich in holes and is now no longer a n-type region, but is a p-type region. There is now no reverse-biased p-n junction to stop current flowing nor a p-n-p sandwich: just one p-region though which current can flow. In the figure to the right the source voltage has changed since with the current flow through the switch the voltage drop from the power supply will appear across some more resistive part of the circuit. An alternative way to look at this is that at the instant the electric field appears across the insulator, the channel region voltage drops to 0V; this voltage forward-biases the Drain-Channel p-n junction and pulls holes from the Drain into the channel; these holes move across the channel towards the Source. While the Gate stays at 0V the channel remains. The p-n-p transistor is commonly called a p-type transistor, because in its conducting phase it becomes all p-type material. Its standard logic symbols are shown to the right. 16
Electro - Principles I
Electro - Principles I Page 10-1 Atomic Theory It is necessary to know what goes on at the atomic level of a semiconductor so the characteristics of the semiconductor can be understood. In many cases a
More informationLECTURE 23. MOS transistor. 1 We need a smart switch, i.e., an electronically controlled switch. Lecture Digital Circuits, Logic
LECTURE 23 Lecture 16-20 Digital Circuits, Logic 1 We need a smart switch, i.e., an electronically controlled switch 2 We need a gain element for example, to make comparators. The device of our dreams
More informationDigital Electronics Part II - Circuits
Digital Electronics Part - Circuits Dr.. J. Wassell Gates from Transistors ntroduction Logic circuits are non-linear, consequently we will introduce a graphical technique for analysing such circuits The
More informationESE370: Circuit-Level Modeling, Design, and Optimization for Digital Systems
ESE370: Circuit-Level Modeling, Design, and Optimization for Digital Systems Lec 6: September 14, 2015 MOS Model You are Here: Transistor Edition! Previously: simple models (0 and 1 st order) " Comfortable
More informationLecture (02) PN Junctions and Diodes
Lecture (02) PN Junctions and Diodes By: Dr. Ahmed ElShafee ١ I Agenda N type, P type semiconductors N Type Semiconductor P Type Semiconductor PN junction Energy Diagrams of the PN Junction and Depletion
More informationITT Technical Institute ET215 Devices I Unit 1
ITT Technical Institute ET215 Devices I Unit 1 Chapter 1 Chapter 2, Sections 2.1-2.4 Chapter 1 Basic Concepts of Analog Circuits Recall ET115 & ET145 Ohms Law I = V/R If voltage across a resistor increases
More informationThis is the 15th lecture of this course in which we begin a new topic, Excess Carriers. This topic will be covered in two lectures.
Solid State Devices Dr. S. Karmalkar Department of Electronics and Communication Engineering Indian Institute of Technology, Madras Lecture - 15 Excess Carriers This is the 15th lecture of this course
More informationLecture 12: MOS Capacitors, transistors. Context
Lecture 12: MOS Capacitors, transistors Context In the last lecture, we discussed PN diodes, and the depletion layer into semiconductor surfaces. Small signal models In this lecture, we will apply those
More informationCurrent mechanisms Exam January 27, 2012
Current mechanisms Exam January 27, 2012 There are four mechanisms that typically cause currents to flow: thermionic emission, diffusion, drift, and tunneling. Explain briefly which kind of current mechanisms
More informationCLASS 1 & 2 REVISION ON SEMICONDUCTOR PHYSICS. Reference: Electronic Devices by Floyd
CLASS 1 & 2 REVISION ON SEMICONDUCTOR PHYSICS Reference: Electronic Devices by Floyd 1 ELECTRONIC DEVICES Diodes, transistors and integrated circuits (IC) are typical devices in electronic circuits. All
More information3C3 Analogue Circuits
Department of Electronic & Electrical Engineering Trinity College Dublin, 2014 3C3 Analogue Circuits Prof J K Vij jvij@tcd.ie Lecture 1: Introduction/ Semiconductors & Doping 1 Course Outline (subject
More informationESE370: Circuit-Level Modeling, Design, and Optimization for Digital Systems. Today MOS MOS. Capacitor. Idea
ESE370: Circuit-Level Modeling, Design, and Optimization for Digital Systems Day 9: September 26, 2011 MOS Model Today MOS Structure Basic Idea Semiconductor Physics Metals, insulators Silicon lattice
More informationAtoms? All matters on earth made of atoms (made up of elements or combination of elements).
Chapter 1 Atoms? All matters on earth made of atoms (made up of elements or combination of elements). Atomic Structure Atom is the smallest particle of an element that can exist in a stable or independent
More informationA SEMICONDUCTOR DIODE. P-N Junction
A SEMICONDUCTOR DIODE P-N Junction Analog Electronics Pujianto Department of Physics Edu. State University of Yogyakarta A Semiconductor Devices A Semiconductor devices can be defined as a unit which consists,
More information! Previously: simple models (0 and 1 st order) " Comfortable with basic functions and circuits. ! This week and next (4 lectures)
ESE370: CircuitLevel Modeling, Design, and Optimization for Digital Systems Lec 6: September 14, 2015 MOS Model You are Here: Transistor Edition! Previously: simple models (0 and 1 st order) " Comfortable
More informationESE370: Circuit-Level Modeling, Design, and Optimization for Digital Systems
ESE370: Circuit-Level Modeling, Design, and Optimization for Digital Systems Lec 6: September 18, 2017 MOS Model You are Here: Transistor Edition! Previously: simple models (0 and 1 st order) " Comfortable
More informationLecture 0: Introduction
Lecture 0: Introduction Introduction q Integrated circuits: many transistors on one chip q Very Large Scale Integration (VLSI): bucketloads! q Complementary Metal Oxide Semiconductor Fast, cheap, low power
More informationFirst-Hand Investigation: Modeling of Semiconductors
perform an investigation to model the behaviour of semiconductors, including the creation of a hole or positive charge on the atom that has lost the electron and the movement of electrons and holes in
More informationFREQUENTLY ASKED QUESTIONS February 21, 2017
FREQUENTLY ASKED QUESTIONS February 21, 2017 Content Questions How do you place a single arsenic atom with the ratio 1 in 100 million? Sounds difficult to get evenly spread throughout. Yes, techniques
More informationMost matter is electrically neutral; its atoms and molecules have the same number of electrons as protons.
Magnetism Electricity Magnetism Magnetic fields are produced by the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. -> permanent magnets Magnetic
More informationLecture (02) Introduction to Electronics II, PN Junction and Diodes I
Lecture (02) Introduction to Electronics II, PN Junction and Diodes I By: Dr. Ahmed ElShafee ١ Agenda Current in semiconductors/conductors N type, P type semiconductors N Type Semiconductor P Type Semiconductor
More informationDigital Electronics Part II Electronics, Devices and Circuits
Digital Electronics Part Electronics, Devices and Circuits Dr.. J. Wassell ntroduction n the coming lectures we will consider how logic gates can be built using electronic circuits First, basic concepts
More informationIntroduction to Semiconductor Devices
Physics 233 Experiment 48 Introduction to Semiconductor Devices References 1. G.W. Neudeck, The PN Junction Diode, Addison-Wesley MA 1989 2. Background notes (Appendix A) 3. Specification sheet for Diode
More informationEngineering 2000 Chapter 8 Semiconductors. ENG2000: R.I. Hornsey Semi: 1
Engineering 2000 Chapter 8 Semiconductors ENG2000: R.I. Hornsey Semi: 1 Overview We need to know the electrical properties of Si To do this, we must also draw on some of the physical properties and we
More informationElectronic Devices And Circuits. Introduction
Electronic Devices And Circuits Introduction An electronic device controls the movement of electrons. The study of electronic devices requires a basic understanding of the relationship between electrons
More informationIntroduction to Semiconductor Physics. Prof.P. Ravindran, Department of Physics, Central University of Tamil Nadu, India
Introduction to Semiconductor Physics 1 Prof.P. Ravindran, Department of Physics, Central University of Tamil Nadu, India http://folk.uio.no/ravi/cmp2013 Review of Semiconductor Physics Semiconductor fundamentals
More informationSOLID STATE ELECTRONICS DIGITAL ELECTRONICS SOFT CONDENSED MATTER PHYSICS
SOLID STATE ELECTRONICS DIGITAL ELECTRONICS SOFT CONDENSED MATTER PHYSICS The energy band occupied by the valence electrons is called valence band and is the highest filled band. Bnd occupied by the electrons
More informationElectronics Fets and Mosfets Prof D C Dube Department of Physics Indian Institute of Technology, Delhi
Electronics Fets and Mosfets Prof D C Dube Department of Physics Indian Institute of Technology, Delhi Module No. #05 Lecture No. #02 FETS and MOSFETS (contd.) In the previous lecture, we studied the working
More informationElectronic Devices & Circuits
Electronic Devices & Circuits For Electronics & Communication Engineering By www.thegateacademy.com Syllabus Syllabus for Electronic Devices Energy Bands in Intrinsic and Extrinsic Silicon, Carrier Transport,
More informationDesigning Information Devices and Systems II A. Sahai, J. Roychowdhury, K. Pister Discussion 1A
EECS 16B Spring 2019 Designing Information Devices and Systems II A. Sahai, J. Roychowdhury, K. Pister Discussion 1A 1 Semiconductor Physics Generally, semiconductors are crystalline solids bonded into
More information! Previously: simple models (0 and 1 st order) " Comfortable with basic functions and circuits. ! This week and next (4 lectures)
ESE370: CircuitLevel Modeling, Design, and Optimization for Digital Systems Lec 6: September 18, 2017 MOS Model You are Here: Transistor Edition! Previously: simple models (0 and 1 st order) " Comfortable
More informationElectronics The basics of semiconductor physics
Electronics The basics of semiconductor physics Prof. Márta Rencz, Gergely Nagy BME DED September 16, 2013 The basic properties of semiconductors Semiconductors conductance is between that of conductors
More informationIntroduction to Semiconductor Devices
Physics 233 Experiment 48 Introduction to Semiconductor Devices References 1. G.W. Neudeck, The PN Junction Diode, Addison-Wesley MA 1989 2. Background notes (Appendix A) 3. Specification sheet for Diode
More informationReview of Semiconductor Physics. Lecture 3 4 Dr. Tayab Din Memon
Review of Semiconductor Physics Lecture 3 4 Dr. Tayab Din Memon 1 Electronic Materials The goal of electronic materials is to generate and control the flow of an electrical current. Electronic materials
More informationSemiconductors. Semiconductors also can collect and generate photons, so they are important in optoelectronic or photonic applications.
Semiconductors Semiconducting materials have electrical properties that fall between true conductors, (like metals) which are always highly conducting and insulators (like glass or plastic or common ceramics)
More informationSection 12: Intro to Devices
Section 12: Intro to Devices Extensive reading materials on reserve, including Robert F. Pierret, Semiconductor Device Fundamentals Bond Model of Electrons and Holes Si Si Si Si Si Si Si Si Si Silicon
More informationSemiconductor Physics fall 2012 problems
Semiconductor Physics fall 2012 problems 1. An n-type sample of silicon has a uniform density N D = 10 16 atoms cm -3 of arsenic, and a p-type silicon sample has N A = 10 15 atoms cm -3 of boron. For each
More informationType of material Numbers of FREE electrons Resitsivity/ resitance Insulator LOW HIGH Semi-Conductor MEDIUM MEDIUM Conductor HIGH LOW
9.4.3 2 (i) Identify that some electrons in solids are shared between atoms and move freely There are three main ways in which matter is held together. They all involve the valence or outer shell electrons.
More informationESE 570: Digital Integrated Circuits and VLSI Fundamentals
ESE 570: Digital Integrated Circuits and VLSI Fundamentals Lec 4: January 29, 2019 MOS Transistor Theory, MOS Model Penn ESE 570 Spring 2019 Khanna Lecture Outline! CMOS Process Enhancements! Semiconductor
More informationFree Electron Model for Metals
Free Electron Model for Metals Metals are very good at conducting both heat and electricity. A lattice of in a sea of electrons shared between all nuclei (moving freely between them): This is referred
More informationFree Electron Model for Metals
Free Electron Model for Metals Metals are very good at conducting both heat and electricity. A lattice of in a sea of electrons shared between all nuclei (moving freely between them): This is referred
More informationPhysics Department. CfE Higher Unit 3: Electricity. Problem Booklet
Physics Department CfE Higher Unit 3: Electricity Problem Booklet Name Class 1 Contents Exercise 1: Monitoring and measuring a.c. Exercise 2: Current, voltage, power and resistance Exercise 3: Electrical
More informationEE 446/646 Photovoltaic Devices I. Y. Baghzouz
EE 446/646 Photovoltaic Devices I Y. Baghzouz What is Photovoltaics? First used in about 1890, the word has two parts: photo, derived from the Greek word for light, volt, relating to electricity pioneer
More informationSEMICONDUCTORS. Conductivity lies between conductors and insulators. The flow of charge in a metal results from the
SEMICONDUCTORS Conductivity lies between conductors and insulators The flow of charge in a metal results from the movement of electrons Electros are negatively charged particles (q=1.60x10-19 C ) The outermost
More informationQuiz #1 Practice Problem Set
Name: Student Number: ELEC 3908 Physical Electronics Quiz #1 Practice Problem Set? Minutes January 22, 2016 - No aids except a non-programmable calculator - All questions must be answered - All questions
More informationelectronics fundamentals
electronics fundamentals circuits, devices, and applications THOMAS L. FLOYD DAVID M. BUCHLA Lesson 1: Diodes and Applications Semiconductors Figure 1-1 The Bohr model of an atom showing electrons in orbits
More informationEE 5211 Analog Integrated Circuit Design. Hua Tang Fall 2012
EE 5211 Analog Integrated Circuit Design Hua Tang Fall 2012 Today s topic: 1. Introduction to Analog IC 2. IC Manufacturing (Chapter 2) Introduction What is Integrated Circuit (IC) vs discrete circuits?
More informationProcessing of Semiconducting Materials Prof. Pallab Banerji Department of Material Science Indian Institute of Technology, Kharagpur
Processing of Semiconducting Materials Prof. Pallab Banerji Department of Material Science Indian Institute of Technology, Kharagpur Lecture - 4 Doping in Semiconductors Good morning. Let us start with
More informationESE 570: Digital Integrated Circuits and VLSI Fundamentals
ESE 570: Digital Integrated Circuits and VLSI Fundamentals Lec 4: January 23, 2018 MOS Transistor Theory, MOS Model Penn ESE 570 Spring 2018 Khanna Lecture Outline! CMOS Process Enhancements! Semiconductor
More informationESE 570: Digital Integrated Circuits and VLSI Fundamentals
ESE 570: Digital Integrated Circuits and VLSI Fundamentals Lec 4: January 24, 2017 MOS Transistor Theory, MOS Model Penn ESE 570 Spring 2017 Khanna Lecture Outline! Semiconductor Physics " Band gaps "
More informationNanoelectronics. Topics
Nanoelectronics Topics Moore s Law Inorganic nanoelectronic devices Resonant tunneling Quantum dots Single electron transistors Motivation for molecular electronics The review article Overview of Nanoelectronic
More informationBasic Semiconductor Physics
6 Basic Semiconductor Physics 6.1 Introduction With this chapter we start with the discussion of some important concepts from semiconductor physics, which are required to understand the operation of solar
More informationElectronic Circuits 1. Transistor Devices. Contents BJT and FET Characteristics Operations. Prof. C.K. Tse: Transistor devices
Electronic Circuits 1 Transistor Devices Contents BJT and FET Characteristics Operations 1 What is a transistor? Three-terminal device whose voltage-current relationship is controlled by a third voltage
More informationSolid State Electronics. Final Examination
The University of Toledo EECS:4400/5400/7400 Solid State Electronic Section elssf08fs.fm - 1 Solid State Electronics Final Examination Problems Points 1. 1. 14 3. 14 Total 40 Was the exam fair? yes no
More informationDavid J. Starling Penn State Hazleton PHYS 214
Being virtually killed by a virtual laser in a virtual space is just as effective as the real thing, because you are as dead as you think you are. -Douglas Adams, Mostly Harmless David J. Starling Penn
More information! CMOS Process Enhancements. ! Semiconductor Physics. " Band gaps. " Field Effects. ! MOS Physics. " Cut-off. " Depletion.
ESE 570: Digital Integrated Circuits and VLSI Fundamentals Lec 4: January 9, 019 MOS Transistor Theory, MOS Model Lecture Outline CMOS Process Enhancements Semiconductor Physics Band gaps Field Effects
More informationConcept of Core IENGINEERS- CONSULTANTS LECTURE NOTES SERIES ELECTRONICS ENGINEERING 1 YEAR UPTU. Page 1
Concept of Core Conductivity of conductor and semiconductor can also be explained by concept of Core. Core: Core is a part of an atom other than its valence electrons. Core consists of all inner shells
More informationMOSFET: Introduction
E&CE 437 Integrated VLSI Systems MOS Transistor 1 of 30 MOSFET: Introduction Metal oxide semiconductor field effect transistor (MOSFET) or MOS is widely used for implementing digital designs Its major
More informationSolids. Solids are everywhere. Looking around, we see solids. Composite materials make airplanes and cars lighter, golf clubs more powerful,
Solids Solids are everywhere. Looking around, we see solids. Most of our electronics is solid state. Composite materials make airplanes and cars lighter, golf clubs more powerful, In addition to hard matter
More informationUNIVERSITY OF CALIFORNIA College of Engineering Department of Electrical Engineering and Computer Sciences. EECS 130 Professor Ali Javey Fall 2006
UNIVERSITY OF CALIFORNIA College of Engineering Department of Electrical Engineering and Computer Sciences EECS 130 Professor Ali Javey Fall 2006 Midterm 2 Name: SID: Closed book. Two sheets of notes are
More informationCLASS 12th. Semiconductors
CLASS 12th Semiconductors 01. Distinction Between Metals, Insulators and Semi-Conductors Metals are good conductors of electricity, insulators do not conduct electricity, while the semiconductors have
More informationLecture Outline. ESE 570: Digital Integrated Circuits and VLSI Fundamentals. Review: MOSFET N-Type, P-Type. Semiconductor Physics.
ESE 57: Digital Integrated Circuits and VLSI Fundamentals Lec 4: January 24, 217 MOS Transistor Theory, MOS Model Lecture Outline! Semiconductor Physics " Band gaps " Field Effects! MOS Physics " Cutoff
More informationSemiconductor Physics fall 2012 problems
Semiconductor Physics fall 2012 problems 1. An n-type sample of silicon has a uniform density N D = 10 16 atoms cm -3 of arsenic, and a p-type silicon sample has N A = 10 15 atoms cm -3 of boron. For each
More informationREVISED HIGHER PHYSICS REVISION BOOKLET ELECTRONS AND ENERGY
REVSED HGHER PHYSCS REVSON BOOKLET ELECTRONS AND ENERGY Kinross High School Monitoring and measuring a.c. Alternating current: Mains supply a.c.; batteries/cells supply d.c. Electrons moving back and forth,
More informationISSUES TO ADDRESS...
Chapter 12: Electrical Properties School of Mechanical Engineering Choi, Hae-Jin Materials Science - Prof. Choi, Hae-Jin Chapter 12-1 ISSUES TO ADDRESS... How are electrical conductance and resistance
More informationSection 12: Intro to Devices
Section 12: Intro to Devices Extensive reading materials on reserve, including Robert F. Pierret, Semiconductor Device Fundamentals EE143 Ali Javey Bond Model of Electrons and Holes Si Si Si Si Si Si Si
More informationSemiconductor Physics Problems 2015
Semiconductor Physics Problems 2015 Page and figure numbers refer to Semiconductor Devices Physics and Technology, 3rd edition, by SM Sze and M-K Lee 1. The purest semiconductor crystals it is possible
More informationIntroduction to Transistors. Semiconductors Diodes Transistors
Introduction to Transistors Semiconductors Diodes Transistors 1 Semiconductors Typical semiconductors, like silicon and germanium, have four valence electrons which form atomic bonds with neighboring atoms
More informationLecture 11: MOS Transistor
Lecture 11: MOS Transistor Prof. Niknejad Lecture Outline Review: MOS Capacitors Regions MOS Capacitors (3.8 3.9) CV Curve Threshold Voltage MOS Transistors (4.1 4.3): Overview Cross-section and layout
More informationOhm s Law and Electronic Circuits
Production Ohm s Law and Electronic Circuits Page 1 - Cyber Security Class ELECTRICAL CIRCUITS All you need to be an inventor is a good imagination and a pile of junk. -Thomas Edison Page 2 - Cyber Security
More informationEE301 Electronics I , Fall
EE301 Electronics I 2018-2019, Fall 1. Introduction to Microelectronics (1 Week/3 Hrs.) Introduction, Historical Background, Basic Consepts 2. Rewiev of Semiconductors (1 Week/3 Hrs.) Semiconductor materials
More informationChapter 2 The Well 9/5/2017. E E 480 Introduction to Analog and Digital VLSI Paul M. Furth New Mexico State University
hapter 2 The Well E E 480 Introduction to Analog and Digital VLSI Paul M. Furth New Mexico State University p+ sub ~ 150 m thick, p-epi ~ 30 m thick All transistors go in p- epi layer Typical p- doping
More informationUnit IV Semiconductors Engineering Physics
Introduction A semiconductor is a material that has a resistivity lies between that of a conductor and an insulator. The conductivity of a semiconductor material can be varied under an external electrical
More informationLecture Number - 01 Metals, Semiconductors and Insulators
Electronic Materials, Devices and Fabrication Dr. S. Parasuraman Department of Metallurgical and Materials Engineering Indian Institute of Technology, Madras Lecture Number - 01 Metals, Semiconductors
More informationQualitative Picture of the Ideal Diode. G.R. Tynan UC San Diego MAE 119 Lecture Notes
Qualitative Picture of the Ideal Diode G.R. Tynan UC San Diego MAE 119 Lecture Notes Band Theory of Solids: From Single Attoms to Solid Crystals Isolated Li atom (conducting metal) Has well-defined, isolated
More information12/10/09. Chapter 18: Electrical Properties. View of an Integrated Circuit. Electrical Conduction ISSUES TO ADDRESS...
Chapter 18: Electrical Properties ISSUES TO ADDRESS... How are electrical conductance and resistance characterized? What are the physical phenomena that distinguish? For metals, how is affected by and
More informationLow Power VLSI Circuits and Systems Prof. Ajit Pal Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur
Low Power VLSI Circuits and Systems Prof. Ajit Pal Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur Lecture No. # 08 MOS Inverters - III Hello, and welcome to today
More informationSemiconductor Physics
Semiconductor Physics Motivation Is it possible that there might be current flowing in a conductor (or a semiconductor) even when there is no potential difference supplied across its ends? Look at the
More informationFloating Point Representation and Digital Logic. Lecture 11 CS301
Floating Point Representation and Digital Logic Lecture 11 CS301 Administrative Daily Review of today s lecture w Due tomorrow (10/4) at 8am Lab #3 due Friday (9/7) 1:29pm HW #5 assigned w Due Monday 10/8
More informationHigher Physics. Electricity. Summary Notes. Monitoring and measuring a.c. Current, potential difference, power and resistance
Higher Physics Electricity Summary Notes Monitoring and measuring a.c. Current, potential difference, power and resistance Electrical sources and internal resistance Capacitors Conductors, semiconductors
More informationContents CONTENTS. Page 2 of 47
J. A. Hargreaves Lockerbie Academy June 2015 Contents CONTENTS Contents... 2 CHAPTER 7 CONDUCTORS, SEMICONDUCTORS AND INSULATORS... 4 Summary of Content... 4 Summary of this chapter- notes from column
More informationThe photovoltaic effect occurs in semiconductors where there are distinct valence and
How a Photovoltaic Cell Works The photovoltaic effect occurs in semiconductors where there are distinct valence and conduction bands. (There are energies at which electrons can not exist within the solid)
More information! CMOS Process Enhancements. ! Semiconductor Physics. " Band gaps. " Field Effects. ! MOS Physics. " Cut-off. " Depletion.
ESE 570: Digital Integrated Circuits and VLSI Fundamentals Lec 4: January 3, 018 MOS Transistor Theory, MOS Model Lecture Outline! CMOS Process Enhancements! Semiconductor Physics " Band gaps " Field Effects!
More informationDigital Electronics Electronics, Devices and Circuits
Digital Electronics Electronics, Devices and Circuits Dr. I. J. Wassell Introduction In the coming lectures we will consider how logic gates can be built using electronic circuits First, basic concepts
More informationElectronics EC /2/2012. * In-class exams: 40% 7 th week exam 25% 12 th week exam 15%
Arab Academy for Science, Technology and Maritime Transport Electronics EC 331 Dr. Mohamed Hassan Course Assessment * In-class exams: 40% 7 th week exam 25% 12 th week exam 15% *Tutorial exams and activities:
More informationECE201 Electron Devices. Presented by K.Pandiaraj ECE Kalasalingam University
ECE201 Electron Devices Presented by K.Pandiaraj ECE Kalasalingam University Atom Atoms are the main building blocks of matter. All the materials are made up of very small particles called atoms. For example
More informationLarry Zhang. Office: DH
CSC258 Week 1 1 Larry Zhang Office: DH-3070 Email: ylzhang@cs.toronto.edu 2 Today s outline Why CSC258 What is in CSC258 How to do well in CSC258 Start learning 3 Why takecsc258? 4 Learning the Magic magic
More informationLecture 20: Semiconductor Structures Kittel Ch 17, p , extra material in the class notes
Lecture 20: Semiconductor Structures Kittel Ch 17, p 494-503, 507-511 + extra material in the class notes MOS Structure Layer Structure metal Oxide insulator Semiconductor Semiconductor Large-gap Semiconductor
More informationReview Energy Bands Carrier Density & Mobility Carrier Transport Generation and Recombination
Review Energy Bands Carrier Density & Mobility Carrier Transport Generation and Recombination The Metal-Semiconductor Junction: Review Energy band diagram of the metal and the semiconductor before (a)
More informationCMPEN 411 VLSI Digital Circuits. Lecture 03: MOS Transistor
CMPEN 411 VLSI Digital Circuits Lecture 03: MOS Transistor Kyusun Choi [Adapted from Rabaey s Digital Integrated Circuits, Second Edition, 2003 J. Rabaey, A. Chandrakasan, B. Nikolic] CMPEN 411 L03 S.1
More information! PN Junction. ! MOS Transistor Topology. ! Threshold. ! Operating Regions. " Resistive. " Saturation. " Subthreshold (next class)
ESE370: ircuitlevel Modeling, Design, and Optimization for Digital Systems Lec 7: September 20, 2017 MOS Transistor Operating Regions Part 1 Today! PN Junction! MOS Transistor Topology! Threshold! Operating
More information1. (a) What is the meaning of semiconductor? [1 mark]
TRIAL KEDAH 05 ESSAY SECTION B. (a) What is the meaning of semiconductor? [ mark] (b) Diagram 0. shows a boron (B) atom embedded among silicon (Si) atoms in a semiconductor. In Diagram 0. the embedded
More informationSemiconductors (Chất1bán1dẫn)
To describe the properties of n-type and p-type semiconductors and how a pn jun formed To study a diode and the characteristics of diode 1-1 Atomic Structure Atomic1Structure An atom is the smallest particle
More informationSemiconductors & LEDs
Semiconductors & LEDs Day 37, Phys 2130 Questions? Semiconductors &LEDs Next up: EPR, Entanglement, Bell, Bound State Sim.. Many Wells 2 1 In solid, `10 22 atoms/cm 3, many!! electrons, and levels countless
More informationFundamentals of the Metal Oxide Semiconductor Field-Effect Transistor
Triode Working FET Fundamentals of the Metal Oxide Semiconductor Field-Effect Transistor The characteristics of energy bands as a function of applied voltage. Surface inversion. The expression for the
More informationMOS Transistor I-V Characteristics and Parasitics
ECEN454 Digital Integrated Circuit Design MOS Transistor I-V Characteristics and Parasitics ECEN 454 Facts about Transistors So far, we have treated transistors as ideal switches An ON transistor passes
More informationSession 0: Review of Solid State Devices. From Atom to Transistor
Session 0: Review of Solid State Devices From Atom to Transistor 1 Objective To Understand: how Diodes, and Transistors operate! p n p+ n p- n+ n+ p 2 21 Century Alchemy! Ohm s law resistivity Resistivity
More information6.012 Electronic Devices and Circuits
Page 1 of 12 YOUR NAME Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology 6.012 Electronic Devices and Circuits FINAL EXAMINATION Open book. Notes: 1. Unless
More informationDiodes. EE223 Digital & Analogue Electronics Derek Molloy 2012/2013.
Diodes EE223 Digital & Analogue Electronics Derek Molloy 2012/2013 Derek.Molloy@dcu.ie Diodes: A Semiconductor? Conductors Such as copper, aluminium have a cloud of free electrons weak bound valence electrons
More informationMOS CAPACITOR AND MOSFET
EE336 Semiconductor Devices 1 MOS CAPACITOR AND MOSFET Dr. Mohammed M. Farag Ideal MOS Capacitor Semiconductor Devices Physics and Technology Chapter 5 EE336 Semiconductor Devices 2 MOS Capacitor Structure
More information