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Schottky Contact

The rectifying contact that occur between a metal and a lightly doped semiconductor.

Schottky1                    Schottky

a)                                                                      b)

Figure(1) a) Energy band diagram of a metal and semiconductor before contact,
 b) Ideal energy -band diagram of a metal and n-type semiconductor junction.

If a metal work function $\phi_m$ is larger than a semiconductor electron affinity  $\chi$, therefore contacting metal to the semiconductor leads to electron flow from the semiconductor to the metal as a prerequisite of Fermi levels alignment and thermal equilibrium. The remaining positively charged atoms in the semiconductor part create a space charge region. Thus electron flows from semiconductor to metal see a barrier of height $\phi_{BO}$ known as Schottky barrier.

 $\phi_{BO}=(\phi_m-\chi)$