Intrinsic & Extrinsic Materials

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

Comments

Naturally an individual atom has orbitals of different energy levels which can be represented by wave functions. When the atoms are brought together, their antibonding atoms diminisles and bonding orbitals form a band of energy.

Qualitative Band Diagram of Intrinsic and Extrinsic Materials

Probablity Distribution Function

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.

Solid State Devices

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