Metals, semiconductors, and insulators metals have free electrons and partially filled valence bands, therefore they are highly conductive a. Optical properties of crystalline s emiconductors and insulators interband absorption in direct and indirect band gap sc luminescence. A very poor conductor of electricity is termed as insulator. Ravindran, phy02e semiconductor physics, autum 20 17 december. Conductors, insulators and semiconductors conductors. This information will give you a bit of background as to why some elements are good insulators. Though ostensibly for a physics audience, the book is. The reader may overlook the equations with no loss of comprehension, or may use the text to find appropriate equations for calculations of optical properties. To classify optical properties and electrical properties of materials according to material type, structure and physical properties. Semiconductors are substances with properties somewhere between them. Physics explains the theories, properties and mathematical approach governing semiconductors. An electron placed in the conduction band of a polar insulator or semiconductor. Band structures, electronic and optical properties of metals. Correlation between optical electronegativity and refractive.
The size reduction is more prominent in the case of semiconductors as compared to metals i. Insulators are mostly nonmetallic solids which have extremely high resistance towards the flow of charge and do not allow the charge to flow through them. Distinction between metals, semiconductors and insulators. Colour in metals, semiconductors and insulators colour and. The properties of a plasma injected into an insulator or semiconductor are analytically describable if diffusive current flow is neglected. We differentiate the elements around us on the basis of their physical properties such as malleability, phase, texture, colour, polarity, solubility etc. Pdf optical properties of crystalline semiconductors and. Jan 03, 2016 this video provides a brief overview of atomic make up of conductors, semiconductors and insulators. Devin mackenzie washington research foundation professor of clean energy assoc. Electrical properties can be indicated by resistivity.
Semiconductors have resistivities in between those of metals and insulators. Electrical and optical properties uppsala university. The copper and aluminium are good examples of a conductor. While the doping of insulators can dramatically change their optical properties, it is not enough to overcome the large band gap to make them good conductors of electricity. Distinction between metals, semiconductors and insulators according to band theory, the electrons in a solid can possess bands of energies called allowed bands of energies and these electrons may not possess some other bands of energies called forbidden bands of energies. Fermi energy, statistics of electron distribution electronic structure of semiconductors. Semiconductor technology from a to z the link article above should provide you with a start point on this subject.
Mse352 functional properties of materials i spring 2018 lecture notes 3. May 24, 2017 a good conductor allows the electric current to pass through it freely while an insulator does not allow the electric current to pass through it. Conductors and insulators examples, definition, properties. A metal which is very good carrier of electricity is called conductor. It is significant that the conductivity of these materials can. A special group of materials fall into an intermediate category called semiconductors. Stefan zollner, february 2019, optical properties of solids lecture 6 7. For insulators colour is mostly defined by absorption and. Curves f, c, and e were made with the same three samples, one pyrex, one metallic selenium, and one vitreous selenium. Doped semiconductors behave just like a metal, except for the lower carrier density. However, the doping of semiconductors has a much more dramatic effect on their electrical conductivity and is the basis for solid state electronics. Insulators, metals, and semiconductors 220 an excellent introductory level text is the one written by mark fox. This class discusses the origin of electrical, magnetic and optical properties of materials, with a focus on the acquisition of quantum mechanical tools. The innovative text gives an introductory treatment of the optical properties of solids.
Compound semiconductors gaas, cdse always have some degree of ionicity. Yu and cardona, fundamentals of semiconductors, springer verlag 1996 1. Today optical properties of materials insulators lattice absorption, color centers semiconductorsenergy bands, urbach tail, excitons metals response due to bound and free electrons, plasma oscillations origin frequency dependence of cin real materials lorentz model harmonic oscillator model nw n n n1. Insulators have a full valence band and a large energy gap a few ev. The usual way to determine the optical properties of a solid is to shine monochromatic light. Crystalline insulators and semiconductors glasses molecular materials not treated, see bibliography metals. Chapter 19 electrical properties university of tennessee. It is significant that the conductivity of these materials can be varied over orders of magnitude by changes. Semiconductor devices introduction to materials science for engineers, ch. Solid state physics part ii optical properties of solids mit.
It begins with an analysis of the properties of materials, presentation of the postulates of quantum mechanics, and close examination of the hydrogen atom, simple molecules and bonds, and the behavior of electrons in solids and energy bands. For pure semiconductors the colour depends on the energy gap e g. Ex amples of such optical devices include the diode lasers which ar e the heart of dvd and cd player s and chargecoupl ed. Photons are used to excite the electrons to higher states absorbed within 0.
Semiconductors have similar band structure as insulators but with a much smaller band gap. Insulators lattice absorption, color centers semiconductors energy bands, urbach tail, excitons metals. Optical and photoelectric effects in insulators and semiconductors 631 curve for a given pair of samples could be reproduced more closely than this. It covers many of the topics we will examine, and it is a great all around reference. The glass, wood, mica, diamond are the examples of an insulator. In metals, the conduction band and the valence band come very closer to each other and may even overlap, with the fermi energy ef somewhere inside. A substance that conducts electricity is called a conductor, and a substance that does not conduct electricity is called an insulator. The previous lecture today optical properties of materials insulators lattice absorption, color centers semiconductors energy bands, urbach tail, excitons metals response due to bound and free electrons, plasma oscillations origin frequency dependence of cin real materials lorentz model harmonic oscillator model nw n n n1. Opti 434 electrical and optical properties of materials. Electrical, optical, and magnetic properties of materials. Conductors such as gold, silver and copper have low resistance and conduct electricity easily.
Some semiconducting materials include silicon, germanium, and. Semiconductor, any of a class of crystalline solids intermediate in electrical conductivity between a conductor and an insulator. Chapter 1 crystal properties and growth of semiconductors. Introduction to materials science chapter 19, thermal properties 19 heat conduction in nonmetallic materials in insulators and semiconductors the heat transfer is by phonons and, generally, is lower than in metals. Application to semiconductors and insulators request pdf. Conductors, semiconductors, and insulators youtube.
Optical properties of metals, semiconductors and devices dr. The overall theme of the collection is electronic and optical properties of metals, semiconductors, and insulators. Colour and the optical properties of materials, 3rd edition. Solid state physics part ii optical properties of solids.
Optical properties of solids department of physics. A good conductor allows the electric current to pass through it freely while an insulator does not allow the electric current to pass through it. Colour and the optical properties of materials, 3rd. Metals, semiconductors and insulators are distinguished from each others by their band structures. The central theme ofthe book is the dielectric function a macroscopic quantity and its relationshiptothe fundamentalmicroscopic electronic. Ex amples of such optical devices include the diode lasers which ar e the heart. Their band structures are shown in the figure below. Bassani and pastoriparravicini, electronic states and optical transitions in solids, pergamon press, ny 1975. Ph8252 physics for information science syllabus notes.
Optical properties of semiconductors photonics research group. Lecture notes 3 optical properties of metals, semiconductors. It begins with an analysis of the properties of materials, presentation of the postulates of quantum mechanics, and close examination of the hydrogen atom, simple molecules and bonds, and the behavior of electrons in solids and. Lecture 1 introduction to semiconductors and semiconductor. From metals to insulators disordered metals and alloys scattering processes metalinsulator transition amorphous semiconductors band conduction hopping conduction amorphous insulators polarons band tails. Osa interband transitions in semimetals, semiconductors. Pdf optical properties of solids download full pdf. Electrical and optical properties of materials part 1. Ravindran, optical properties of semiconductors uio. Properties of conductors, semiconductors and insulators. Semiconductors types, examples, properties, application, uses. There are links mentioned in the article, which should enable you to obtain more answers. Semiconductors are a group of materials having electrical conductivities intermediate between metals and insulators.
Energy profile for a semiconductor photocathode and metal anode. Herve and vandamme relation is modified employing optical electronegativity and its validity tested for elemental compounds, binary and ternary chalcopyrites, semiconductors, insulators, oxides and alkali halides. The relatively small band gaps of semiconductors allow for excitation of electrons from the lower valence band to the upper conduction band by reasonable amounts of thermal or optical energy. This filled band, however, overlaps with the next higher band, therefore they are conductive but with slightly higher resistivity than normal metals b. Some electrons can jump to the empty conduction band by thermal or optical excitation.
Most of the learning objects either require knowledge of or explicitly refer to band structures, either at a basic level or a more advanced level. The purpose of the present paper is to study the dependence of optical electronegativity and refractive index. Anna university physics for information science syllabus notes question bank question papers. The fundamental principles of absorption, reflection, luminescence and light scattering are discussed for a wide range of materials, including crystalline insulators and semiconductors, glasses, metals, and molecular materials. Optical properties of solids electron spectroscopy group. However it is known from experimental and theoretical. Some semiconducting materials include silicon, germanium, and carbon. This video provides a brief overview of atomic make up of conductors, semiconductors and insulators. Optical properties of metalsoptical properties of metals. Semiconductors are the materials which have a conductivity between conductors generally metals and nonconductors or insulators such ceramics. In solids the discrete levels broaden to form allowed bands which are separated by bandgaps.
Topics band structure and its relation to electrical and optical properties of materials, metals, insulators, thin films, semiconductors, gain and cavities, lasers, nonlinear and electrooptic properties. This fourth year option covers the optical properties of metals, semiconductors and insulators following the treatment given in my textbook of the same name. The fundamental principles of absorption, reflection, luminescence and light scattering are discussed for a wide range of materials, including crystalline insulators and semiconductors, glasses, metals,and molecular materials. Semiconductors can be compounds such as gallium arsenide or pure elements, such as germanium or silicon. Pdf optical properties of solids download full pdf book.
Key features presents the optical properties of metals, insulators, semiconductors, laser materials, and nonlinear materials. Semiconductors are employed in the manufacture of various kinds of electronic devices, including diodes, transistors, and integrated circuits. Insulators, semiconductors and metals energy bands and the gaps between them determine the conductivity and other properties of solids. Optical and photoelectric effects in insulators and.
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