Solid State Devices

Electrons are fermions, which satisfy the exclusion principle. So, it maintains the Fermi-Dirac distribution. Where, K is Boltzmann’s constant. K=1.38×10 -23 J/K Or K=8.62×10 -5 eV/K T is absolute temperature. E F is Fermi level. Let, E=E F So that, f(E)= ½ So E F is the Fermi energy level at which the PDF is ½ . If T=0K the distribution takes the simple rectangular, shown in figure.

Intrinsic Material: The material in which the electron and the hole concentration are same, is known as intrinsic material. Electron concentration, n o = Hole concentration, p o Electron concentration, n i = Hole concentration, p i Extrinsic Material: The carrier concentration (no & po) are not same i.e. they differes from intrinsic concentration (ni & pi), is known as extrinsic material. Electron concentration, n o ≠ Hole concentration, p o Electron concentration, n i ≠ Hole concentration, p i Also n i ≠ n o and p o ≠ n i

The mass of electron in free space differes from the massin solid, due to different energy levels or bands. The mass in solid is represented by effective mass. It is denoted by M e * or M n *.