# Solid State Electronic Devices Theory

## Friday, October 8, 2010

## Sunday, October 3, 2010

### Probablity Distribution Function

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 & Extrinsic Materials

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}

### Effective Mass

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}*.