Semiconductor - Revision history

DavidB4-bot: Spelling, grammar, and general fixes, typos fixed: As a result → As a result,

2016-06-24T15:31:46Z

Spelling, grammar, and general fixes, typos fixed: As a result → As a result,

Spielman: super-->semi and qualify the statement

2012-09-09T20:13:49Z

super-->semi and qualify the statement

Jpatt: Reverted edits by Drperson (Talk) to last version by NathanG

2009-05-27T03:41:35Z

Reverted edits by Drperson (Talk) to last version by NathanG

NathanG: sp "electric"

2008-02-26T01:49:42Z

sp "electric"

EQ: Corrected errors, still needs to be expanded

2007-08-19T03:21:47Z

Corrected errors, still needs to be expanded

Learn together: Link

2007-07-28T15:19:19Z

Link

Learn together: Category, bold

2007-07-28T15:06:11Z

Category, bold

EQ: New page: A semiconductor is a conductor whose resistance decreases with increased temperature. Superconductors consist of a lattice of a group four element, typically silicon or germanium. ...

2007-07-28T14:22:15Z

New page: A semiconductor is a conductor whose resistance decreases with increased temperature. Superconductors consist of a lattice of a group four element, typically silicon or germanium. ...

New page

A semiconductor is a conductor whose resistance decreases with increased temperature. Superconductors consist of a lattice of a group four element, typically [[silicon]] or [[germanium]]. The [[electrons]] that cause current flow are bound in the lattice, with on average 1 free electron per 250,000 atoms. When energy (usually heat) is supplied to the conductor electrons are freed from the lattice and conduction occurs. More energy increases the number of free electrons up to a point where the substance loses its conductivity.

==Band Theory==

Electrons held in the lattice and unable to conduct electricity are referred to as being in the "valance band" (as they are in the outer shell of the atom). Electrons which have been promoted to higher energy orbitals and are free to conduct are referred to as being in the "conduction band".

==Positive Hole Theory==

The positive hole theory is that when an electron leaves its position in the lattice a positive hole is formed in its absence. This hole is then filled by another electron which in turn leaves a hole in its path which is filled by another electron and so on so forth. The apparant movement of "positive holes" mimicks the movement of positive charges, and hence semiconductors can be referred to as conducting by positive holes.

==Doping==

Doping occurs when a group four atom in the lattice is replaced with either a group three or a group five atom at the rate of about one per one million.

===p type===

p type semiconductors occur when the lattice is doped with a group three element. As these elements only have three valance electrons there is a positive hole already in existence in the lattice, which reduces the energy required to promote electrons to the conduction band (no need to displace an electron initially), hence increasing the efficiency of the substance.

===n type===

n type semiconductors occur when the lattice is doped with a group give element. As these elements have five valance electrons there is an extra electron "floating" in the lattice (only four valance electrons are needed to bond to other atoms), and as such the amount of energy required to start the conduction is reduced, also increasing the efficiency of the substance.

==Uses==

Semiconductors are not used to replace ordinary conductors, given that their resistance remains significantly higher at all temperatures. However, their unique properties can be exploited by creating a n-p junction, when an n-type and a p-type semiconductor are placed together. The electrons in the conduction band of the n-type substance fill up some of the positive holes in the p-type conduction, producing a negative charge on the p-type side and hence an electic field which creates a "zone of exclusion". This zone of exclusion can be utilised in many instances, including in solid state devices acting as diodes (ensuring direction of current in one direction only) and triodes (increasing the current flowing through a circuit) and in solar cells. The former of these has replaced transistor valves in appliances such as radios and photocells.

@@ Line 23: / Line 23: @@
 ===n type===
-n type semiconductors occur when the lattice is doped with a group give element. As these elements have five valance electrons there is an extra electron "floating" in the lattice (only four valance electrons are needed to bond to other atoms). As a result conduction can occur without needing to input large amounts of energy, and the majority charge carriers are electrons in the conduction band (the minority charge carriers being positive holes).
+n type semiconductors occur when the lattice is doped with a group give element. As these elements have five valance electrons there is an extra electron "floating" in the lattice (only four valance electrons are needed to bond to other atoms). As a result, conduction can occur without needing to input large amounts of energy, and the majority charge carriers are electrons in the conduction band (the minority charge carriers being positive holes).
 ==Uses==
@@ Line 29: / Line 29: @@
 Semiconductors are not used to replace ordinary conductors, given that their resistance remains significantly higher at all temperatures. However, their unique properties can be exploited by creating a n-p junction, when an n-type and a p-type semiconductor are placed together. The electrons in the conduction band of the n-type substance fill up some of the positive holes in the p-type conduction, producing a negative charge on the p-type side and hence an electric field which creates a "zone of exclusion". This zone of exclusion can be utilized in many instances, including in solid state devices acting as diodes (ensuring direction of current in one direction only) and triodes (increasing the current flowing through a circuit) and in solar cells. The former of these has replaced transistor valves in appliances such as radios and photocells.
-[[Category: Technology]]
+[[Category:Technology]]

← Older revision		Revision as of 20:13, September 9, 2012
Line 1:		Line 1:
−	A '''semiconductor''' is a conductor whose resistance decreases with increased temperature. ~~Superconductors~~ consist of a lattice of a group four element, typically [[silicon]] or [[germanium]]. The [[electron]]s that cause current flow are bound in the lattice, with on average 1 free electron per 250,000 atoms. When energy (usually heat) is supplied to the conductor electrons are freed from the lattice and conduction occurs. More energy increases the number of free electrons up to a point where the substance loses its conductivity.	+	A '''semiconductor''' is a conductor whose resistance decreases with increased temperature. Semiconductors in common commercial use consist of a lattice of a group four element, typically [[silicon]] or [[germanium]]. The [[electron]]s that cause current flow are bound in the lattice, with on average 1 free electron per 250,000 atoms. When energy (usually heat) is supplied to the conductor electrons are freed from the lattice and conduction occurs. More energy increases the number of free electrons up to a point where the substance loses its conductivity.

	==Theories Behind Semiconductors==		==Theories Behind Semiconductors==

@@ Line 11: / Line 11: @@
 ===Positive Hole Theory===
-The positive hole theory is that when an electron leaves its position in the lattice a positive hole is formed in its absence. This hole is then filled by another electron which in turn leaves a hole in its path which is filled by another electron and so on so forth. The apparant movement of "positive holes" mimicks the movement of positive charges, and hence semiconductors can be referred to as conducting by positive holes. This occurs in the valance band.
+The positive hole theory is that when an electron leaves its position in the lattice a positive hole is formed in its absence. This hole is then filled by another electron which in turn leaves a hole in its path which is filled by another electron and so on so forth. The apparent movement of "positive holes" mimics the movement of positive charges, and hence semiconductors can be referred to as conducting by positive holes. This occurs in the valance band.
 ==Doping==
@@ Line 27: / Line 27: @@
 ==Uses==
-Semiconductors are not used to replace ordinary conductors, given that their resistance remains significantly higher at all temperatures. However, their unique properties can be exploited by creating a n-p junction, when an n-type and a p-type semiconductor are placed together. The electrons in the conduction band of the n-type substance fill up some of the positive holes in the p-type conduction, producing a negative charge on the p-type side and hence an electic field which creates a "zone of exclusion". This zone of exclusion can be utilised in many instances, including in solid state devices acting as diodes (ensuring direction of current in one direction only) and triodes (increasing the current flowing through a circuit) and in solar cells. The former of these has replaced transistor valves in appliances such as radios and photocells.
+Semiconductors are not used to replace ordinary conductors, given that their resistance remains significantly higher at all temperatures. However, their unique properties can be exploited by creating a n-p junction, when an n-type and a p-type semiconductor are placed together. The electrons in the conduction band of the n-type substance fill up some of the positive holes in the p-type conduction, producing a negative charge on the p-type side and hence an electric field which creates a "zone of exclusion". This zone of exclusion can be utilized in many instances, including in solid state devices acting as diodes (ensuring direction of current in one direction only) and triodes (increasing the current flowing through a circuit) and in solar cells. The former of these has replaced transistor valves in appliances such as radios and photocells.
 [[Category: Technology]]

← Older revision		Revision as of 15:19, July 28, 2007
Line 1:		Line 1:
−	A '''semiconductor''' is a conductor whose resistance decreases with increased temperature. Superconductors consist of a lattice of a group four element, typically [[silicon]] or [[germanium]]. The [[~~electrons~~]] that cause current flow are bound in the lattice, with on average 1 free electron per 250,000 atoms. When energy (usually heat) is supplied to the conductor electrons are freed from the lattice and conduction occurs. More energy increases the number of free electrons up to a point where the substance loses its conductivity.	+	A '''semiconductor''' is a conductor whose resistance decreases with increased temperature. Superconductors consist of a lattice of a group four element, typically [[silicon]] or [[germanium]]. The [[electron]]s that cause current flow are bound in the lattice, with on average 1 free electron per 250,000 atoms. When energy (usually heat) is supplied to the conductor electrons are freed from the lattice and conduction occurs. More energy increases the number of free electrons up to a point where the substance loses its conductivity.

	==Band Theory==		==Band Theory==

← Older revision	Revision as of 03:41, May 27, 2009
(No difference)

@@ Line 1: / Line 1: @@
 A '''semiconductor''' is a conductor whose resistance decreases with increased temperature. Superconductors consist of a lattice of a group four element, typically [[silicon]] or [[germanium]]. The [[electron]]s that cause current flow are bound in the lattice, with on average 1 free electron per 250,000 atoms. When energy (usually heat) is supplied to the conductor electrons are freed from the lattice and conduction occurs. More energy increases the number of free electrons up to a point where the substance loses its conductivity.
-==Band Theory==
+==Theories Behind Semiconductors==
-Electrons held in the lattice and unable to conduct electricity are referred to as being in the "valance band" (as they are in the outer shell of the atom). Electrons which have been promoted to higher energy orbitals and are free to conduct are referred to as being in the "conduction band".
+Conduction in semiconductors is through two methods, conduction through electrons free of the lattice (those in the conduction band) and conduction by positive holes.
-==Positive Hole Theory==
+===Band Theory===
-The positive hole theory is that when an electron leaves its position in the lattice a positive hole is formed in its absence. This hole is then filled by another electron which in turn leaves a hole in its path which is filled by another electron and so on so forth. The apparant movement of "positive holes" mimicks the movement of positive charges, and hence semiconductors can be referred to as conducting by positive holes.
+Electrons held in the lattice and unable to conduct electricity are referred to as being in the "valance band" (as they are in the outer shell of the atom). Electrons which have been promoted to higher energy orbitals and are free to conduct are referred to as being in the "conduction band". Electrons in the conduction band are able to transmit electricity.
 ==Doping==
@@ Line 15: / Line 19: @@
 ===p type===
-p type semiconductors occur when the lattice is doped with a group three element. As these elements only have three valance electrons there is a positive hole already in existence in the lattice, which reduces the energy required to promote electrons to the conduction band (no need to displace an electron initially), hence increasing the efficiency of the substance.
+p type semiconductors occur when the lattice is doped with a group three element. As these elements only have three valance electrons there is a positive hole already in existence in the lattice, which allows ready conduction by positive holes. As a result, the majority charge carriers in p-type semiconductors are positive holes, and the minority charge carriers are electrons in the conduction band.
 ===n type===
-n type semiconductors occur when the lattice is doped with a group give element. As these elements have five valance electrons there is an extra electron "floating" in the lattice (only four valance electrons are needed to bond to other atoms), and as such the amount of energy required to start the  conduction is reduced, also increasing the efficiency of the substance.
+n type semiconductors occur when the lattice is doped with a group give element. As these elements have five valance electrons there is an extra electron "floating" in the lattice (only four valance electrons are needed to bond to other atoms). As a result conduction can occur without needing to input large amounts of energy, and the majority charge carriers are electrons in the conduction band (the minority charge carriers being positive holes).
 ==Uses==