Friday, October 8, 2010
Sunday, October 3, 2010
Where, K is Boltzmann’s constant.
T is absolute temperature.
EF is Fermi level.
So that, f(E)= ½
So EF is the Fermi energy level at which the PDF is ½ .
If T=0K the distribution takes the simple rectangular, shown in figure.
The material in which the electron and the hole concentration are same, is known as intrinsic material.
Electron concentration, no = Hole concentration, po
Electron concentration, ni = Hole concentration, pi
The carrier concentration (no & po) are not same i.e. they differes from intrinsic concentration (ni & pi), is known as extrinsic material.
Electron concentration, no ≠ Hole concentration, po
Electron concentration, ni ≠ Hole concentration, pi
Also ni ≠ no and po ≠ ni
An empty state in the valence band is reffered to as hole.
Electron Hole Pair(EHP):
If the conduction band electron and the hole are created by the excitation of a valence band electron to the conduction band, they are called an electron-hole pair.