Valence band - Revision history

Jmdonev: 1 revision imported: Doing upload, largely of old redirects.

2018-06-04T16:52:32Z

1 revision imported: Doing upload, largely of old redirects.

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Jmdonev at 21:51, 1 June 2018

2018-06-01T21:51:09Z

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	[[Category:Done ~~2015~~-08-21]]		[[Category:Done 2018-06-01]]
	[[File:Conduction band.png\|360px\|thumbnail\|Figure 1.<ref>Wikimedia Commons. ''File:Isolator-metal.svg'' [Online]. Available: https://commons.wikimedia.org/wiki/File:Isolator-metal.svg</ref> A diagram showing the valence and conduction bands of insulators, metals, and semiconductors. The Fermi level is the name given to the highest energy occupied electron orbital at [[absolute zero]].<ref name = b>UC Davis ChemWiki. (August 17, 2015). ''Band Theory of Semiconductors'' [Online]. Available: http://chemwiki.ucdavis.edu/u_Materials/Electronic_Properties/Band_Theory_of_Semiconductors</ref>]]		[[File:Conduction band.png\|360px\|thumbnail\|Figure 1.<ref>Wikimedia Commons. ''File:Isolator-metal.svg'' [Online]. Available: https://commons.wikimedia.org/wiki/File:Isolator-metal.svg</ref> A diagram showing the valence and conduction bands of insulators, metals, and semiconductors. The Fermi level is the name given to the highest energy occupied electron orbital at [[absolute zero]].<ref name = b>UC Davis ChemWiki. (August 17, 2015). ''Band Theory of Semiconductors'' [Online]. Available: http://chemwiki.ucdavis.edu/u_Materials/Electronic_Properties/Band_Theory_of_Semiconductors</ref>]]

	<onlyinclude>The '''valence band''' is the band of [[electron]] orbitals that electrons can jump out of, moving into the [[conduction band]] when excited. The valence band is simply the outermost electron orbital of an [[atom]] of any specific material that electrons actually occupy.</onlyinclude> This is closely related to the idea of the [[valence electron]].		<onlyinclude>The '''valence band''' is the band of [[electron]] orbitals that electrons can jump out of, moving into the [[conduction band]] when excited. The valence band is simply the outermost electron orbital of an [[atom]] of any specific material that electrons actually occupy.</onlyinclude> This is closely related to the idea of the [[valence electron]].

	The [[energy]] difference between the highest occupied energy state of the valence band and the lowest unoccupied state of the conduction band is called the [[band gap]] and is indicative of the [[conductivity]] of a material.<ref>University of Cambridge. (August 17, 2015). ''Introduction to Energy Bands'' [Online]. Available:http://www.doitpoms.ac.uk/tlplib/semiconductors/energy_band_intro.php</ref> A large band gap means that a lot of energy is required to excite valence electrons to the conduction band. Conversely, when the valence band and conduction band overlap as they do in [[metal]]s, electrons can readily jump between the two bands (see Figure 1) meaning the material is highly conductive.<ref name=hp1>Hyperphysics. (August 17, 2015). ''Conductor Energy Bands'' [Online]. Available:http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c6</ref>		The [[energy]] difference between the highest occupied energy state of the valence band and the lowest unoccupied state of the conduction band is called the [[band gap]] and is indicative of the [[electrical conductivity]] of a material.<ref>University of Cambridge. (August 17, 2015). ''Introduction to Energy Bands'' [Online]. Available:http://www.doitpoms.ac.uk/tlplib/semiconductors/energy_band_intro.php</ref> A large band gap means that a lot of energy is required to excite valence electrons to the conduction band. Conversely, when the valence band and conduction band overlap as they do in [[metal]]s, electrons can readily jump between the two bands (see Figure 1) meaning the material is highly conductive.<ref name=hp1>Hyperphysics. (August 17, 2015). ''Conductor Energy Bands'' [Online]. Available:http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c6</ref>

	The difference between [[conductor]]s, [[insulator]]s, and [[semiconductor]]s can be shown by how large their band gap is.<ref>Hyperphysics. (August 17, 2015). ''Band Theory of Solids'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c1		The difference between [[conductor]]s, [[insulator]]s, and [[semiconductor]]s can be shown by how large their band gap is.<ref>Hyperphysics. (August 17, 2015). ''Band Theory of Solids'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c1

J.williams: 1 revision imported

2015-08-26T21:31:56Z

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J.williams at 18:50, 24 August 2015

2015-08-24T18:50:49Z

New page

[[Category:Done 2015-08-21]]
[[File:Conduction band.png|360px|thumbnail|Figure 1.<ref>Wikimedia Commons. ''File:Isolator-metal.svg'' [Online]. Available: https://commons.wikimedia.org/wiki/File:Isolator-metal.svg</ref> A diagram showing the valence and conduction bands of insulators, metals, and semiconductors. The Fermi level is the name given to the highest energy occupied electron orbital at [[absolute zero]].<ref name = b>UC Davis ChemWiki. (August 17, 2015). ''Band Theory of Semiconductors'' [Online]. Available: http://chemwiki.ucdavis.edu/u_Materials/Electronic_Properties/Band_Theory_of_Semiconductors</ref>]]

<onlyinclude>The '''valence band''' is the band of [[electron]] orbitals that electrons can jump out of, moving into the [[conduction band]] when excited. The valence band is simply the outermost electron orbital of an [[atom]] of any specific material that electrons actually occupy.</onlyinclude> This is closely related to the idea of the [[valence electron]].

The [[energy]] difference between the highest occupied energy state of the valence band and the lowest unoccupied state of the conduction band is called the [[band gap]] and is indicative of the [[conductivity]] of a material.<ref>University of Cambridge. (August 17, 2015). ''Introduction to Energy Bands'' [Online]. Available:http://www.doitpoms.ac.uk/tlplib/semiconductors/energy_band_intro.php</ref> A large band gap means that a lot of energy is required to excite valence electrons to the conduction band. Conversely, when the valence band and conduction band overlap as they do in [[metal]]s, electrons can readily jump between the two bands (see Figure 1) meaning the material is highly conductive.<ref name=hp1>Hyperphysics. (August 17, 2015). ''Conductor Energy Bands'' [Online]. Available:http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c6</ref>

The difference between [[conductor]]s, [[insulator]]s, and [[semiconductor]]s can be shown by how large their band gap is.<ref>Hyperphysics. (August 17, 2015). ''Band Theory of Solids'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c1
</ref> Insulators are characterized by a large band gap, so a prohibitively large amount of energy is required to move electrons out of the valence band to form a current.<ref name=hp2>Hyperphysics. (August 17, 2015). ''Insulator Energy Bands'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c4
</ref> Conductors have an overlap between the conduction and valence bands, so the valence electrons in such conductors are essentially free.<ref name=hp1/> Semiconductors, on the other hand, have a small band gap that allows for a meaningful fraction of the valence electrons of the material to move into the conduction band given a certain amount of energy. This property gives them a conductivity between conductors and insulators, which is part of the reason why they are ideal for circuits as they will not cause a short circuit like a conductor.<ref name= b/> This band gap also allows semiconductors to convert light into electricity in photovoltaic cells and to emit light as LEDs when made into certain types of diodes. Both these processes rely on the energy absorbed or released by electrons moving between the conduction and valence bands.

==References==
{{reflist}}[[Category:Uploaded]]