From WikiChip
Difference between revisions of "drift current"

 
(2 intermediate revisions by one other user not shown)
Line 35: Line 35:
 
:<math>J = \sigma E = \frac{E}{\rho}</math>
 
:<math>J = \sigma E = \frac{E}{\rho}</math>
  
−
Where <math>\sigma</math> is the [[conductivity]] [1/Ωcm] and <math>\rho</math> is the resistivity [Ωcm].
+
Where <math>\sigma</math> is the [[conductivity]] [1/Ωcm] and <math>\rho</math> is the [[resistivity]] [Ωcm].
 +
 
 +
=== Diffusion vs Drift currents ===
 +
{{see also|diffusion current}}
 +
{| class="wikitable"
 +
|-
 +
! || Diffusion current || Drift current
 +
|-
 +
| Result of || Having mass || Having charge
 +
|-
 +
| Due to || Carrier movement due to concentration gradient || Carrier movement due to electric field applying a force
 +
|-
 +
| Obey || [[Fick's law]] || [[Ohm's law]]
 +
|}
  
 
== See also ==
 
== See also ==
−
* [[diffusion current]]
+
* [[Diffusion current]]
 +
* [[Stokes-Einstein Relation]]

Latest revision as of 20:03, 5 August 2018

Drift current is the current that is a result of an applied electric field.

Overview[edit]

The drift current is the net charge of all the charge carrier at the carrier drift velocity. The drift velocity is defined as

Equation v Subscript d Baseline equals mu Subscript n comma p Baseline upper E

There are Equation n free electrons per cubic meter of this material, each with have an elementary charge Equation q .

Drift current density Equation upper J Subscript n Superscript drift due to free electrons

Equation upper J Subscript n Superscript drift Baseline equals minus q n v Subscript d n Baseline equals q n mu Subscript n Baseline upper E

While the current density Equation upper J Subscript p Superscript drift due to holes is

Equation upper J Subscript p Superscript drift Baseline equals q p v Subscript d p Baseline equals q p mu Subscript p Baseline upper E

The total drift current density is the sum of the two drift current densities.

Equation StartLayout 1st Row 1st Column upper J Superscript drift 2nd Column equals upper J Subscript n Superscript drift Baseline plus upper J Subscript p Superscript drift Baseline 2nd Row 1st Column Blank 2nd Column equals q n mu Subscript n Baseline upper E plus q n mu Subscript p Baseline upper E 3rd Row 1st Column Blank 2nd Column equals q left-parenthesis n mu Subscript n Baseline plus p mu Subscript p Baseline right-parenthesis upper E EndLayout

Where the conductivity Equation sigma is

Equation sigma equals q left-parenthesis n mu Subscript n Baseline plus p mu Subscript p Baseline right-parenthesis

which is the generalized form of Ohm's law.

Equation upper J equals sigma upper E equals StartFraction upper E Over rho EndFraction

Where Equation sigma is the conductivity [1/Ωcm] and Equation rho is the resistivity [Ωcm].

Diffusion vs Drift currents[edit]

See also: diffusion current
Diffusion current Drift current
Result of Having mass Having charge
Due to Carrier movement due to concentration gradient Carrier movement due to electric field applying a force
Obey Fick's law Ohm's law

See also[edit]

Retrieved from "https://en.wikichip.org/w/index.php?title=drift_current&oldid=81067"