1 Semiconductors Band Formation & direct and indirect gaps 1 Prof.P. Ravindran, Department of Physics, Central University of Tamil Nadu, India
2 Review of Energy Bands (1) In crystalline solids, the atoms are assembled in a periodical arrangement, in such a way as to minimize the energy of the system Example: NaCl crystal (ionic bound) In the solid, the separation between the constituting atoms is comparable to the atomic size, so the properties of the individual atoms are altered by the presence of neighbouring atoms. Kasap, S.O., Principles of electrical engineering materials and devices, McGraw-Hill, 1997
3 Energy bands Resulting from principles of quantum physics Discrete energy levels: More atoms more energy levels of electrons: There are so many of them that they form energy bands: The discrete (allowed) energy levels of an atom become energy bands in a crystal lattice 3
4 Energy Bands - Solids When atoms approach to form molecules, Pauli s exclusion principle assumes a fundamental role. When two atoms are completely isolated from each other, in a way that there s no interaction of electrons w.d.f, they can have identical electronic structures. As the space between the atoms becomes smaller, electron f.d.o superposition occurs. As stated previously, Pauli s Exclusion Principle says that two different electrons can not be described by the same quantum state; so, an unfolding of the isolated atom s discrete energy levels into new corresponding levels to the electron pair occurs.
5 In order to form a solid, many atoms are brought together. Consequently, the unfolded energy levels form, essentially, continuous energy bands. As an example, the next picture shows an imaginary Si crystal formation from isolated Si atoms. As the distance between atoms approaches the equilibrium inter-atomic separation of the Si crystal, this band unfolds into two bands separated by an energy gap, Eg.
6 Silica Diamond Semiconductors Glass Si Ge Fe Cu They have an electrical conductivity whose value is in between the metal and the insulators conductivity. Insulator semicondutores Metals -1 cm -1
7 Semiconductors Elementary Semiconductors : Si and Ge Semicondutores Composites: Binary: ZnO, GaN, SiC, InP,GaAs Ternary: AlGaAs, GaAsP, HgCdTe, Quaternarys: InGaAsP, AlInGaP. Transistors, diodes and ICs: Si e Ge LEDs: GaAs,GaN, GaP Lasers: AlGaInAs, InGaAsP, GaAs, AlGaAs Detectors: Si, InGaAsP, CdSe, InSb, HgCdTe
8 Semiconductors The semiconductor conductivity can be changed through : Temperature Optical Excitation Impurity Doping Devices based on semiconductors are fast and consume low energies; Semiconductors devices are compact and can be integrated into IC s; Semiconductors devices are cheap.
9 .:: Semiconductor, Insulators, Conductors ::. Full band Empty band All energy levels are occupied by electrons Both full and empty bands do not partake in electrical conduction. All energy levels are empty ( no electrons)
10 Electron energy.:: Semiconductor energy bands at low temperature ::. Empty conduction band At low temperatures the valance band is full, and the conduction band is empty. Recall that a full band can not conduct, and neither can an empty band. Forbidden energy gap [Eg] At low temperatures, semiconductors do not conduct, they behave like insulators. Full valance band The thermal energy of the electrons sitting at the top of the full band is much lower than that of the Eg at low temperatures.
11 Conduction Electron : Assume some kind of energy is provided to the electron (valence electron) sitting at the top of the valance band. This electron gains energy from the applied field and it would like to move into higher energy states. This electron contributes to the conductivity and this electron is called as a conduction electron. At 0 0 K, electron sits at the lowest energy levels. The valance band is the highest filled band at zero kelvin. Forbidden energy gap [Eg] Empty conduction band Full valance band
12 Semiconductor energy bands at room temperature When enough energy is supplied to the e - sitting at the top of the valance band, e - can make a transition to the bottom of the conduction band. When electron makes such a transition it leaves behind a missing electron state. This missing electron state is called as a hole. Hole behaves as a positive charge carrier. Magnitude of its charge is the same with that of the electron but with an opposite sign. +e- +e- +e- +eenergy Empty conduction band Forbidden energy gap [Eg] Full valance band
13 Doped and undoped Semicondcutors ::. Holes contribute to current in valance band (VB) as e - s are able to create current in conduction band (CB). Hole is not a free particle. It can only exist within the crystal. A hole is simply a vacant electron state. A transition results an equal number of e - in CB and holes in VB. This is an important property of intrinsic, or undoped semiconductors. For extrinsic, or doped, semiconductors this is no longer true.
14 Electron energy Bipolar (two carrier) conduction empty occupied After transition Valance Band (partly filled band) After transition, the valance band is now no longer full, it is partly filled and may conduct electric current. The conductivity is due to both electrons and holes, and this device is called a bipolar conductor or bipolar device.
15 What kind of excitation mechanism can cause an e- to make a transition from the top of the valance band (VB) to the minimum or bottom of the conduction band (CB)? Answer : Thermal energy? Electrical field? Electromagnetic radiation? To have a partly field band configuration in a semiconductor, one must use one of these excitation mechanisms. Eg Partly filled CB Partly filled VB Energy band diagram of a Semiconductor at a finite temperature.
16 1-Thermal Energy : Thermal energy = k x T = 1.38 x J/K x 300 K =25 mev Excitation rate = constant x exp(-eg / kt) Although the thermal energy at room temperature, RT, is very small, i.e. 25 mev, a few electrons can be promoted to the CB. Electrons can be promoted to the CB by means of thermal energy. This is due to the exponential increase of excitation rate with increasing temperature. Excitation rate is a strong function of temperature.
17 2- Electric field : For low fields, this mechanism doesn t promote electrons to the CB in common semiconductors such as Si and GaAs. An electric field of V/m can provide an energy of the order of 1 ev. This field is enormous. So, the use of the electric field as an excitation mechanism is not useful way to promote electrons in semicondcutors.
18 3- Electromagnetic Radiation : c E h h (6.62x10 J s) x(3x10 m / s) / ( m) E( ev ) (in m) h = 6.62 x J-s c = 3 x 10 8 m/s 1 ev=1.6x10-19 J 1.24 for Silicon Eg 1.1 ev ( m) 1.1 mn 1.1 Near infrared To promote electrons from VB to CB Silicon, the wavelength of the photons must 1.1 μm or less
19 Conduction Band e- + Valance Band photon The converse transition can also happen. An electron in CB recombines with a hole in VB and generate a photon. The energy of the photon will be in the order of Eg. If this happens in a direct bandgap semiconductor, it forms the basis of LED s and LASERS.
20 Insulators : The magnitude of the band gap determines the differences between insulators, s/c s and metals. The excitation mechanism of thermal is not a useful way to promote an electron to CB even the melting temperature is reached in an insulator. Even very high electric fields is also unable to promote electrons across the band gap in an insulator. CB (completely empty) Eg~several electron volts VB (completely full) Wide band gaps between VB and CB
21 Metals : Touching VB and CB CB VB CB VB Overlapping VB and CB These two bands looks like as if partly filled bands and it is known that partly filled bands conducts well. This is the reason why metals have high conductivity. No gap between valance band and conduction band
22 Gap Energy (ev ) Semiconductors Lattice Constant (Å)
23 Material Classification based on Size of Bandgap Ease of achieving thermal population of conduction band determines whether a material is an insulator, metal, or semiconductor.
24 Metals, Semiconductors, and Insulators Range of conductivities exhibited by various materials. Insulators A l u m i n a M a n y c e r a m ic s Semiconductors Conductors Superconductors D ia m o n d I n o r g a n ic G la s s e s M ic a P o ly p r o p y le n e S o d a s ilic a g la s s P V D F P E T SiO 2 B o r o s ilic a te P u r e S n O 2 I n tr in s ic S i A m o rp h o u s A s S e I n tr in s ic G a A s 2 3 Metals D e g e n e r a te ly doped Si A llo y s T e G r a p h ite N ic r A g Conductivity ( m)
25 Valance band, conductance band conductance band valance band Valance band these electrons form the chemical bonds almost full Conductance bend electrons here can freely move almost empty v valance band / uppermost full c conductance band / lowermost empty 25
26 Conductors and insulators 26 forbidden gap band gap semiconductor insulator metal For Si: Wg = 1.12 ev for SiO2: Wg = 4.3 ev
27 Energy Band Formation Energy band diagrams. N electrons filling half of the 2N allowed states, as can occur in a metal. A completely empty band separated by an energy gap Eg from a band whose 2N states are completely filled by 2N electrons, representative of an insulator.
28 Metals Ef Ef Metal Semiconductor Allowed electronic-energy-state systems for metal and semiconductors. States marked with an X are filled; those unmarked are empty.
29 Typical band structures of Metal Metals Electron Energy, E Free electron Vacuum level 3p 3s 2p 2s 2s Band 3s Band 2p Band E = 0 Overlappin g energy bands Electrons 1s ATOM 1s SOLID In a metal the various energy bands overlap to give a single band of energies that is only partially full of electrons. There are states with energies up to the vacuum level where the electron is free.
30 Electron Motion in Energy Band Current flowing E = 0 E 0 Electron motion in an allowed band is analogous to fluid motion in a glass tube with sealed ends; the fluid can move in a half-filled tube just as electrons can move in a metal.
31 Electron Motion in Energy Band E = 0 E 0 No fluid motion can occur in a completely filled tube with sealed ends.
32 Energy band diagrams. Energy Band Formation Energy-band diagram for a semiconductor showing the lower edge of the conduction band Ec, a donor level Ed within the forbidden gap, and Fermi level Ef, an acceptor level Ea, and the top edge of the valence band Ev.
33 Electron Motion in Energy Band Fluid analogy for a semiconductor No flow can occur in either the completely filled or completely empty tube. Fluid can move in both tubes if some of it is transferred from the filled tube to the empty one, leaving unfilled volume in the lower tube.
34 E-k diagram, Bloch function. Energy Band Diagram PE(r) r PE of the electron around an isolated atom V(x) 0 a a x=0 a 2a 3a Surface Crystal x=l Surface x When N atoms are arranged to form the crystal then there is an overlap of individual electron PE functions. PE of the electron, V(x), inside the crystal is periodic with a period a. The electron potential energy [PE, V(x)], inside the crystal is periodic with the same periodicity as that of the crystal, a. Far away outside the crystal, by choice, V = 0 (the electron is free and PE = 0).
35 Energy Band Diagram E-k diagram, Bloch function. 2 d 2 dx 2m 2 e E V ( x) 0 V ( x) V ( x ma) m 1,2,3... Schrödinger equation ( x ) U ( x) k k e Periodic Potential i k x Periodic Wave function Bloch Wavefunction There are many Bloch wavefunction solutions to the one-dimensional crystal each identified with a particular k value, say kn which act as a kind of quantum number. Each k (x) solution corresponds to a particular kn and represents a state with an energy Ek.
36 Energy Band Diagram E-k diagram of a direct bandgap semiconductor The E-k Diagram E k The Energy Band Diagram Conduction Band (CB) E g e - E c Empty k hu E c CB e - hu Valence Band (VB) h + E v Occupied k E v h + VB k š /a š /a The E-k curve consists of many discrete points with each point corresponding to a possible state, wavefunction k (x), that is allowed to exist in the crystal. The points are so close that we normally draw the E-k relationship as a continuous curve. In the energy range Ev to Ec there are no points [ k (x), solutions].
37 Energy Band Diagram E-k diagram E E E Direct Bandgap k E g CB VB E c E v Photon k k VB Indirect Bandgap, E g CB E k c cb E v k vb k k E r VB CB E Phonon c E v k GaAs Si Si with a recombination center In GaAs the minimum of the CB is directly above the maximum of the VB. direct bandgap semiconductor. In Si, the minimum of the CB is displaced from the maximum of the VB. indirect bandgap semiconductor Recombination of an electron and a hole in Si involves a recombination center.
38 Direct and indirect-band gap materials : Direct-band gap semiconductors (e.g. GaAs, InP, AlGaAs) CB E For a direct-band gap material, the minimum of the conduction band and maximum of the valance band lies at the same momentum, k, values. e- + k When an electron sitting at the bottom of the CB recombines with a hole sitting at the top of the VB, there will be no change in momentum values. VB Energy is conserved by means of emitting a photon, such transitions are called as radiative transitions.
39 Indirect-band gap s/c s (e.g. Si and Ge) E For an indirect-band gap material; the minimum of the CB and maximum of the VB lie at different k-values. When an e- and hole recombine in an indirect-band gap s/c, phonons must be involved to conserve momentum. CB VB + k e - Eg Phonon Atoms vibrate about their mean position at a finite temperature.these vibrations produce vibrational waves inside the crystal. Phonons are the quanta of these vibrational waves. Phonons travel with a velocity of sound. Their wavelength is determined by the crystal lattice constant. Phonons can only exist inside the crystal.
40 The transition that involves phonons without producing photons are called nonradiative (radiationless) transitions. These transitions are observed in an indirect band gap semiconductors and result in inefficient photon producing. So in order to have efficient LED s and LASER s, one should choose materials having direct band gaps such as compound semiconductors of GaAs, AlGaAs, etc
Doped Semiconductors Dr. Katarzyna Skorupska 1 Doped semiconductors Increasing the conductivity of semiconductors by incorporation of foreign atoms requires increase of the concentration of mobile charge
Lecture 2: Semiconductors: Introduction Contents 1 Introduction 1 2 Band formation in semiconductors 2 3 Classification of semiconductors 5 4 Electron effective mass 10 1 Introduction Metals have electrical
Crystalline solids A solid crystal consists of different atoms arranged in a periodic structure. Crystals can be formed via various bonding mechanisms: Ionic bonding Covalent bonding Metallic bonding Van
Solid State Detectors = Semi-Conductor based Detectors Materials and their properties Energy bands and electronic structure Charge transport and conductivity Boundaries: the p-n junction Charge collection
10p PhD Course Semiconductor Physics 18 Lectures Nov-Dec 2011 and Jan Feb 2012 Literature Semiconductor Physics K. Seeger The Physics of Semiconductors Grundmann Basic Semiconductors Physics - Hamaguchi
Semiconductors, diodes, transistors (Horst Wahl, QuarkNet presentation, June 2001) Electrical conductivity! Energy bands in solids! Band structure and conductivity Semiconductors! Intrinsic semiconductors!
Modern Physics (PHY 3305) Lecture Notes Modern Physics (PHY 3305) Lecture Notes Solid-State Physics: The Theory of Semiconductors (Ch. 10.6-10.8) SteveSekula, 30 March 2010 (created 29 March 2010) Review
The Physics of Energy sources Renewable sources of energy Solar Energy B. Maffei Bruno.email@example.com Renewable sources 1 Solar power! There are basically two ways of using directly the radiative
FYS3410 - Vår 015 (Kondenserte fasers fysikk) http://www.uio.no/studier/emner/matnat/fys/fys3410/v15/index.html Pensum: Introduction to Solid State Physics by Charles Kittel (Chapters 1-9 and 17, 18, 0,
Epitaxy Epitaxial Growth Epitaxy means the growth of a single crystal film on top of a crystalline substrate. For most thin film applications (hard and soft coatings, optical coatings, protective coatings)
ENEE 33, Spr. 09 Supplement I Intrinsic and Extrinsic Semiconductors, Fermi-Dirac Distribution Function, the Fermi level and carrier concentrations Zeynep Dilli, Oct. 2008, rev. Mar 2009 This is a supplement
Physics 551: Solid State Physics F. J. Himpsel Background Most of the objects around us are in the solid state. Today s technology relies heavily on new materials, electronics is predominantly solid state.
The Diode The diode is a two terminal semiconductor device that allows current to flow in only one direction. It is constructed of a P and an N junction connected together. Diode Operation No current flows
SEMICONDUCTOR I: Doping, semiconductor statistics (REF: Sze, McKelvey, and Kittel) Introduction Based on known band structures of Si, Ge, and GaAs, we will begin to focus on specific properties of semiconductors,
INSTITUTE FOR APPIED PHYSICS Physical Practice for earners of Engineering sciences Hamburg University, Jungiusstraße 11 Hall effect 1 Goal Characteristic data of a test semiconductor (Germanium) should
Chapter 12: Electrical Properties Learning Objectives... How are electrical conductance and resistance characterized? What are the physical phenomena that distinguish conductors, semiconductors, and insulators?
Covalent Crystals - covalent bonding by shared electrons in common orbitals (as in molecules) - covalent bonds lead to the strongest bound crystals, e.g. diamond in the tetrahedral structure determined
Energy band diagrams In the atoms, the larger the radius, the higher the electron potential energy Hence, electron position can be described either by radius or by its potential energy In the semiconductor
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
Semiconductor Detectors Calorimetry and Tracking with High Precision Applications 1. Photon spectroscopy with high energy resolution. Vertex detection with high spatial resolution 3. Energy measurement
Advanced Materials Science - Lab Intermediate Physics University of Ulm Solid State Physics Department Electrical Conductivity Translated by Michael-Stefan Rill January 20, 2003 CONTENTS 1 Contents 1 Introduction
Chapter 5 5.6 Doped GaAs Consider the GaAs crystal at 300 K. a. Calculate the intrinsic conductivity and resistivity. Second Edition ( 2001 McGraw-Hill) b. In a sample containing only 10 15 cm -3 ionized
Free Electron Fermi Gas (Kittel Ch. 6) Role of Electrons in Solids Electrons are responsible for binding of crystals -- they are the glue that hold the nuclei together Types of binding (see next slide)
Electronic Structure and the Periodic Table Learning Outcomes (a) Electronic structure (i) Electromagnetic spectrum and associated calculations Electromagnetic radiation may be described in terms of waves.
Matter, Materials, Crystal Structure and Bonding Chris J. Pickard Why should a theorist care? Where the atoms are determines what they do Where the atoms can be determines what we can do Overview of Structure
FUNDAMENTAL PROPERTIES OF SOLAR CELLS January 31, 2012 The University of Toledo, Department of Physics and Astronomy SSARE, PVIC Principles and Varieties of Solar Energy (PHYS 4400) and Fundamentals of
Understanding the p-n Junction by Dr. Alistair Sproul Senior Lecturer in Photovoltaics The Key Centre for Photovoltaic Engineering, UNSW The p-n junction is the fundamental building block of the electronic
Semiconductor Laser Diode Outline This student project deals with the exam question Semiconductor laser diode and covers the following questions: Describe how a semiconductor laser diode works What determines
Handout 3 The nearly-free electron model 3.1 Introduction Having derived Bloch s theorem we are now at a stage where we can start introducing the concept of bandstructure. When someone refers to the bandstructure
Chemical Synthesis Spontaneous organization of molecules into stable, structurally well-defined aggregates at the nanometer length scale. Overview The 1-100 nm nanoscale length is in between traditional
AP CHEMISTRY CHAPTER REVIEW CHAPTER 6: ELECTRONIC STRUCTURE AND THE PERIODIC TABLE You should be familiar with the wavelike properties of light: frequency ( ), wavelength ( ), and energy (E) as well as
CHEM 10113, Quiz 7 December 7, 2011 Name (please print) All equations must be balanced and show phases for full credit. Significant figures count, show charges as appropriate, and please box your answers!
COURSE: PHYSICS DEGREE: COMPUTER ENGINEERING year: 1st SEMESTER: 1st WEEKLY PROGRAMMING WEE K SESSI ON DESCRIPTION GROUPS GROUPS Special room for LECTU PRAC session RES TICAL (computer classroom, audiovisual
Energy Transport Focus on heat transfer Heat Transfer Mechanisms: Conduction Radiation Convection (mass movement of fluids) Conduction Conduction heat transfer occurs only when there is physical contact
Lecture 3: Optical Properties of Bulk and Nano 5 nm The Previous Lecture Origin frequency dependence of χ in real materials Lorentz model (harmonic oscillator model) 0 e - n( ) n' n '' n ' = 1 + Nucleus
THE ELECTRON IN ELECTRIC FIELDS Semiconductors If we were to take two parallel plates and connect a voltage source across them as shown in Figure 1, an electric field would be set up between the plates.
Lecture 3: Optical Properties of Bulk and Nano 5 nm First H/W#1 is due Sept. 10 Course Info The Previous Lecture Origin frequency dependence of χ in real materials Lorentz model (harmonic oscillator model)
DO PHYSICS ONLINE FROM QUANTA TO QUARKS QUANTUM (WAVE) MECHANICS Quantum Mechanics or wave mechanics is the best mathematical theory used today to describe and predict the behaviour of particles and waves.
High Open Circuit Voltage of MQW Amorphous Silicon Photovoltaic Structures ARGYRIOS C. VARONIDES Physics and EE Department University of Scranton 800 Linden Street, Scranton PA, 18510 United States Abstract:
Chapter No: 14 Chapter: Semiconductor Electronics: Materials, Devices And Simple Circuits (ONE MARK QUESTIONS) 1. What is an electronic device? It is a device in which controlled flow of electrons takes
II The Nature of Electromagnetic Radiation The Sun s energy has traveled across space as electromagnetic radiation, and that is the form in which it arrives on Earth. It is this radiation that determines
WAVES AND ELECTROMAGNETIC RADIATION All waves are characterized by their wavelength, frequency and speed. Wavelength (lambda, ): the distance between any 2 successive crests or troughs. Frequency (nu,):
3. Diodes and Diode Circuits 3. Diodes and Diode Circuits TLT-8016 Basic Analog Circuits 2005/2006 1 3.1 Diode Characteristics Small-Signal Diodes Diode: a semiconductor device, which conduct the current
The neral Properties of,,, O 2 and 3 N 4 June 2002 Virginia Semiconductor 1501 Powhatan Street, Fredericksburg, VA 22401-4647 USA Phone: (540) 373-2900, FAX (540) 371-0371 www.virginiasemi.com, firstname.lastname@example.org
Field Effect Transistors (FETs) utilize a conductive channel whose resistance is controlled by an applied potential. 1. Junction Field Effect Transistor (JFET) In JFETs a conducting channel is formed of
9.2 Network Covalent, Ionic, and Metallic Solids YOU ARE EXPECTED TO BE ABLE TO: Classify non-molecular solids as either network covalent solids, ionic solids, or metallic solids. Relate the physical properties
Hard Condensed Matter WZI Tom Gregorkiewicz University of Amsterdam VU-LaserLab Dec 10, 2015 Hard Condensed Matter Cluster Quantum Matter Optoelectronic Materials Quantum Matter Amsterdam Mark Golden Anne
MMIC Design and Technology Fabrication of MMIC Instructor Dr. Ali Medi Substrate Process Choice Mobility & Peak Velocity: Frequency Response Band-Gap Energy: Breakdown Voltage (Power-Handling) Resistivity:
CHAPTER 4 PRE-TEST Arrangement of Electrons in Atoms In the space provided, write the letter of the term that best completes each sentence or best answers each question. 1. Which of the following orbital
FYS3410 - Vår 2014 (Kondenserte fasers fysikk) http://www.uio.no/studier/emner/matnat/fys/fys3410/v14/index.html Pensum: Solid State Physics by Philip Hofmann (Chapters 1-7 and 11) Andrej Kuznetsov delivery
DSH 2004 THE CURRENT-VOLTAGE CHARACTERISTICS OF AN LED AND A MEASUREMENT OF PLANCK S CONSTANT Physics 258/259 I. INTRODUCTION Max Planck (1858-1947) was an early pioneer in the field of quantum physics.
Activity 17 Electromagnetic Radiation Why? Electromagnetic radiation, which also is called light, is an amazing phenomenon. It carries energy and has characteristics of both particles and waves. We can
University of California at Santa Cruz Jack Baskin School of Engineering Electrical Engineering Department EE-145L: Properties of Materials Laboratory Lab 5b: Temperature Dependence of Semiconductor Conductivity
Optical Hyperdoping: Transforming Semiconductor Band Structure for Solar Energy Harvesting 3G Solar Technologies Multidisciplinary Workshop MRS Spring Meeting San Francisco, CA, 5 April 2010 Michael P.
Supplementary Course Topic 3: Quantum Theory of Bonding Molecular Orbital Theory of H 2 Bonding in H 2 and some other simple diatomics Multiple Bonds and Bond Order Bond polarity in diatomic and polyatomic
SUPERCONDUCTIVITY property of complete disappearance of electrical resistance in solids when they are cooled below a characteristic temperature. This temperature is called transition temperature or critical
Periodic Table give up 1e - give up 2e - give up 3e - H Li Be Na Mg K Ca Columns: Similar Valence Structure Sc Oaccept 2e- accept 1e - inert gases S Se F Cl Br He Ne Ar Kr Adapted from Fig. 2.6, Callister
Physics 97 Interatomic forces Section 3: rystal Binding Solids are stable structures, and therefore there exist interactions holding atoms in a crystal together. For example a crystal of sodium chloride
Page of 5 NORGES TEKNISK- NATURVITENSKAPELIGE UNIVERSITET INSTITUTT FOR FYSIKK Fagleg kontakt under eksamen: Institutt for fysikk, Gløshaugen Professor Steinar Raaen, 4896758 Eksamen i Emne TFY40 Faste
A Course Material on Engineering Physics - II By Ms. I.JEENA RAJATHY Mrs.V.HEMALATHA Mr.K.PRAVEEN KUMAR Mr.P.PRAKASH Mr.M.SARAVANAN ASSISTANT PROFESSOR DEPARTMENT OF SCIENCE AND HUMANITIES PHYSICS SASURIE
MSE 542 Final Term Paper Title: Organic Semiconductor for Flexible Electronics Name: Chunhung Huang Introduction: An organic semiconductor is an organic compound that possesses similar properties to inorganic
Diodes What do we use diodes for? Diodes and Transistors protect circuits by limiting the voltage (clipping and clamping) turn AC into DC (voltage rectifier) voltage multipliers (e.g. double input voltage)
MOS (metal-oxidesemiconductor) 李 2003/12/19 Outline Structure Ideal MOS The surface depletion region Ideal MOS curves The SiO 2 -Si MOS diode (real case) Structure A basic MOS consisting of three layers.
AP Chemistry A. Allan Chapter 7 Notes - Atomic Structure and Periodicity 7.1 Electromagnetic Radiation A. Types of EM Radiation (wavelengths in meters) 10-1 10-10 10-8 4 to 7x10-7 10-4 10-1 10 10 4 gamma
HIGHER PHYSICS Electricity http://blog.enn.com/?p=481 1 GWC Revised Higher Physics 12/13 HIGHER PHYSICS a) MONITORING and MEASURING A.C. Can you talk about: a.c. as a current which changes direction and
ECE 331: Introduction to Materials for Electrical Engineers Course Objective... Introduce fundamental concepts in Materials Science and how they are used in ECE You will learn about: material structure
Hello and Welcome to this presentation on LED Basics. In this presentation we will look at a few topics in semiconductor lighting such as light generation from a semiconductor material, LED chip technology,
Concept 1: Properties of Objects and Materials Classify objects and materials by their observable properties. Kindergarten Grade 1 Grade 2 Grade 3 Grade 4 PO 1. Identify the following observable properties
Name: Class: Date: ID: A Unit 12 Practice Test Multiple Choice Identify the choice that best completes the statement or answers the question. 1) A solid has a very high melting point, great hardness, and
Physics 222, Winter 2012 Final Exam April 16, 2012 Instructor: Scott Bergeson Rules for this test 1. This test is open book and open notes, including our class notes page online, and your homework solutions.
: Diffusion Diffusion: the movement of particles in a solid from an area of high concentration to an area of low concentration, resulting in the uniform distribution of the substance Diffusion is process
KINETIC THEORY AND THERMODYNAMICS 1. Basic ideas Kinetic theory based on experiments, which proved that a) matter contains particles and quite a lot of space between them b) these particles always move
Chapter 18: The Structure of the Atom 1. For most elements, an atom has A. no neutrons in the nucleus. B. more protons than electrons. C. less neutrons than electrons. D. just as many electrons as protons.
Interatomic and intermolecular forces. What will be covered? 1. Binding energy: basic concepts 2. Ionic bonding. 3. Chemical bonding. a. Primary bonds. b. Secondary bonds. Why do we need to know this material?
APPLICATION NOTE HIGH TRANSMISSION SILICON (HiTran TM ) FOR INFRARED OPTICAL APPLICATIONS Infrared optical systems require materials that have very good transmission characteristics for infrared wavelengths
Atomic Structure Ron Robertson r2 n:\files\courses\1110-20\2010 possible slides for web\atomicstructuretrans.doc I. What is Light? Debate in 1600's: Since waves or particles can transfer energy, what is
Chemistry 2 Chapter 13: Electrons in Atoms Please do not write on the test Use an answer sheet! 1 point/problem 45 points total 1. Calculate the energy in joules of a photon of red light that has a frequency
Wafer Manufacturing Reading Assignments: Plummer, Chap 3.1~3.4 1 Periodic Table Roman letters give valence of the Elements 2 Why Silicon? First transistor, Shockley, Bardeen, Brattain1947 Made by Germanium
Lecture 5 Page 1 Lecture 5 L5. P1 Solids The free electron gas In a solid state, a few loosely bound valence (outermost and not in completely filled shells) elections become detached from atoms and move
Chapter 6 Photoionization Detectors The photoionization detector (PID) utilizes ultraviolet light to ionize gas molecules, and is commonly employed in the detection of volatile organic compounds (VOCs).
TiO 2 : A New Kind of Water Treatment www.rsc.org/learn-chemistry Registered charity number 207890 3: A new kind of water treatment What is solar disinfection with titanium dioxide and how does it work?