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Drift Current

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

Overview

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

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

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