what is drift current and diffusion current plz explain

Drift current :-

When charges(holes or electrons) move under external electric field  to produce current is called drift current.

It is produced due minority carriers( holes in n–type move from right to left and electrons in P–type move from 

left to right) under the external electric field developed in depletion layer.

Drift current is directed from N type to P type material.

Diffusion current.

The current that is observed when the excess holes diffuse to other side(N type) and the excess electrons diffuse to P type due carrier concentration is called diffusion current. 

Diffusion current is directed from P type to N type material.

If there is no biasing drift current is equal to diffusion current. 

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 Drift and diffusion currents :-

 
→ The flow of charge (ie) current through a semiconductor
material are of two types namely drift & diffusion.
→ (ie) The net current that flows through a (PN junction
diode) semiconductor material has two components
(i)Drift current
(ii)Diffusion current
→ drift current is defined as the flow of electric
current due to the motion of the charge carriers under the influence
of an external electric field.
→ Drift current due to the charge carriers such as free
electrons and holes are the current passing through a square
centimeter perpendicular to the direction of flow.
 
Diffusion current :-
 
→ It is possible for an electric current to flow in a
semiconductor even in the absence of the applied voltage provided
a concentration gradient exists in the material.
→ A concentration gradient exists if the number of either
elements or holes is greater in one region of a semiconductor as
compared to the rest of the Region.
→ In a semiconductor material the change carriers have the
tendency to move from the region of higher concentration to that
of lower concentration of the same type of charge carriers. Thus
the movement of charge carriers takes place resulting in a current
called diffusion current.
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 → The flow of charge (ie) current through a semiconductor material are of two types namely drift & diffusion.

→ (ie) The net current that flows through a (PN junction diode) semiconductor material has two components

(i) Drift current

(ii) Diffusion current

the drift current is defined as the flow of electric current due to the motion of the charge carriers under the influence of an external electric field.

the movement of charge carriers takes place resulting in a current called diffusion current.

 

 

Diagram of the diffusion across a pn junction, with the resultant uncovered space charges, the electric field and the drift currents.

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