The directional movement of charge carriers due to their concentration gradient produces a component of current known as Diffusion current.
The mechanism of transport of charges in a semiconductor when no electric field is applied called diffusion. It is encountered only in semiconductors and is normally absent in conductors.
With no applied voltage if the number of charge carriers (either holes or electrons) in one region of a semiconductor is less compared to the rest of the region then there exist a concentration gradient.
Since the charge carriers are either all electrons or all holes they sine polarity of charge and thus there is a force of repulsion between them.
As a result, the carriers tend to move gradually or diffuse from the region of higher concentration to the region of lower concentration. This process is called diffusion and electric current produced due to this process is called diffusion current.
This process continues until all the carriers are evenly distributed through the material. Hence when there is no applied voltage, the net diffusion current will be zero.
DRIFT CURRENT IN SEMICONDUCTORS
DRIFT CURRENT
If an electron is subjected to an electric field in free space it will accelerate in a straight line form the –ve terminal to the + ve terminal of the applied voltage.
However in the case of conductor …Read More
Zener diodes
Zener diodes
The reverse voltage characteristics of a semiconductor diode including the breakdown region is shown below.
Zener diodes are the diodes which are designed to operate in the breakdown region. They are also …Read More
SEMICONDUCTOR : DEFINITION , TYPES
WHAT ARE SEMICONDUCTORS ?
Semiconductors are those substances whose conductivity lies in between that of a conductor and Insulator.Example: Silicon, germanium, Cealenium, Gallium, arsenide etc.
In terms of energy bands, s…Read More
FILTER CIRCUIT : WHY WE USE ?
We know that the output of the rectifier is pulsating d.c. ie the output obtained by the rectifier is not pure d.c. but it contains some ac components along with the dc o/p.
These ac components are called as Ripples,…Read More
BIASING IN DIODE
BIASING IN DIODE
Connecting a p-n junction to an external d.c. voltage source is called biasing.
1. Forward biasing
2. Reverse biasing
1. Forward biasing
When external voltage applied to the junctio…Read More
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