Lecture

Electrical Conductivity of Metals: Semiconductor Properties

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In course

MSE-101(b): Materials:from chemistry to properties

Ce cours permet l'acquisition des notions essentielles relatives à la structure de la matière, aux équilibres et à la réactivité chimique en liaison avec les propriétés mécaniques, thermiques, électriques, magnétiques et optiques des matériaux. ...

Description

This lecture covers the electrical conductivity of metals, dielectric properties, semiconductor conductivity, and disruptive potential of insulators. It explains the concepts of energy bands, electron states, and functional properties of materials based on their energy gaps.

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Instructors (4)

Arianna Marchioro

Education PhD Thesis | Interfacial Charge Transfer Dynamics in Solid-State Hybrid Organic-Inorganic Solar Cells 2010 – 2014 EPFL Directed by Prof. J.-E. Moser and Prof. M. Grätzel MSc in Molecular and Biological Chemistry | 2008 – 2010 EPFL and Imperial College London (exchange program) BSc in Chemistry | 2005 – 2008 EPFL Professionals experiences Postdoctoral Research Associate 2014–2016 University of Washington, Seatt

Fabien Sorin

Sep 2002-Oct 2007 Ph.D., Department of Materials Science and Engineering, MIT, USA. Supervisor: Prof. Yoel Fink; Thesis: Multi-material, Multifunctional Fiber Devices. After graduating with an engineering degree and a Master of Science in Physics from the Ecole Polytechnique in Palaiseau, France, Prof. Sorin joined the department of Materials Science and Engineering at the Massachusetts Institute of Technology (MIT) in Cambridge, USA for his graduate studies. He worked as a research assistant in the Photonic Bandgap Fibers and Devices Group of Professor Yoel Fink and graduated with a PhD in 2008. His PhD thesis led to the development of a new class of fiber material and devices and he was a pioneer of the field of multi-material fibers. Mar 2008-Oct 2010 Postdoctoral Associate and Research Scientist, Research Laboratory of Electronics, MIT. He then joined the Research Laboratory of Electronics at MIT as a Postdoctoral Associate, and continued as a Research Scientist associate, where he conducted independent research in the emerging field of multi-material fibers and was involved and led a variety of projects in fundamental research as well as in collaborations with local start-ups. Apr 2011 Feb 2013 Research Engineer, Saint-Gobain Recherche, Aubervilliers, France. Surface du Verre et interface Group In 2011, prof. Sorin returned to Europe and joined the company Saint-Gobain in the Saint-Gobain Recherche center, its biggest research center located near Paris in France. As a research engineer, he developed a new research thrust investigating new photonic materials and nanostructures for the energy and building industries. In particular, he and colleagues developed innovative processing approaches to deploy photonic nanostructures for light management over large area substrates, for applications in energy harvesting and saving, and for building materials and windows. Mar 2013 Present Assistant Professor tenure-track, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland. Head of the Photonic materials and fibre devices laboratory (FIMAP) Since March 2013, he is in the department of Materials Science (IMX) at the Ecole Polytechnique Fédérale de Lausanne (EPFL) as an assistant professor tenure-track. He is starting a research group on photonic materials and fiber devices (FIMAP), continuing on developing innovative materials processing approaches and photonic device architectures to develop new solutions in energy harvesting, saving and storage, in sensing and monitoring, health care and smart fabrics.

Official source

Ontological neighbourhood

Physics

Condensed matter physics: Solid-state physics

Related concepts (32)

Electrical resistivity and conductivity

Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm-metre (Ω⋅m).

Semiconductor device

A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum (typically liberated by thermionic emission) or as free electrons and ions through an ionized gas.

Valence and conduction bands

In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level, and thus determine the electrical conductivity of the solid. In nonmetals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. On a graph of the electronic band structure of a semiconducting material, the valence band is located below the Fermi level, while the conduction band is located above it.

Band diagram

In solid-state physics of semiconductors, a band diagram is a diagram plotting various key electron energy levels (Fermi level and nearby energy band edges) as a function of some spatial dimension, which is often denoted x. These diagrams help to explain the operation of many kinds of semiconductor devices and to visualize how bands change with position (band bending). The bands may be coloured to distinguish level filling. A band diagram should not be confused with a band structure plot.

Doping (semiconductor)

In semiconductor production, doping is the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties. The doped material is referred to as an extrinsic semiconductor. Small numbers of dopant atoms can change the ability of a semiconductor to conduct electricity. When on the order of one dopant atom is added per 100 million atoms, the doping is said to be low or light.

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Covers the analysis of measurements and defects engineering in semiconductor devices, including density of states and defect probing.

Semiconductors: Band Structure and Carrier Concentration

Explains band structure, density of states, Fermi distribution, and carrier densities.

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Michel Rappaz

After a PhD in solid state physics (1978) at the Ecole Polytechnique Fédérale de Lausanne (EPFL) and a post-doc at Oak Ridge National Laboratory, Michel Rappaz joined the Institute of Materials of EPFL in 1981. After two years in an engineering company, he came back to EPFL in 1984 where he was nominated Adjunct Professor in 1990 and Full Professor in 2003. He retired from EPFL in 2015 and is now Emeritus Professor and independent consultant for several industries and research centres. His main interests are in phase transformations and solidification, in particular the coupling of macroscopic aspects of heat and mass transfer with microscopic aspects of microstructure and defect formation. Among his diverse achievements, one can mention in particular the development of cellular automata for grain structure predictions and of granular models for hot tearing formation in castings, the coupling of Finite Element method with microscopic models of nucleation and growth, the application of the phase field method to the understanding of various microstructures, the discovery of quasicrystal mediated-nucleation in alloys, and many other studies both fundamental at the microstructure-defect level and more applied at the level of processes. Some of the software developments have been commercialized by a spin-off company founded by his group in 1991 (Calcom SA), now part of the French company ESI. Michel Rappaz initiated in 1992 an annual postgraduate course on solidification which has been attended by more than 900 participants from all over the world. He is presently collaborating closely with another spin-off company started from his group, Novamet SàrL. Michel Rappaz has received several awards, in particular the Mathewson co-author award (1994) and author award (1997) of the American Mineral, Metals and Materials Society (TMS), the Koerber foundation award jointly with Profs Y. Bréchet and M. Asbby (1996), the Sainte-Claire Deville Medal (1996) and the Grand Medal (2011) from the French Materials Society, the Bruce Chalmers Award of TMS (2002), the Mc Donald Memorial Lecture award of Canada (2005), the FEMS European Materials Gold Medal (2013) and the Brimacombe Prize of TMS (2015). He is a highly-cited author of ISI, a fellow of ASM, IOP and TMS, and has co-authored more than 200 publications and two books.

Related concepts (32)

Electrical resistivity and conductivity

Semiconductor device

Valence and conduction bands

Band diagram

Doping (semiconductor)