While a pure (so-called intrinsic) semiconductor just as temperature resistance can serve with the technique of doping a large variety of applications. Here, the semiconductor material specifically with foreign atoms (the so-called Dotierstoff / Dotieratomen) polluted, with the aim of the charge density to influence.
There are Dotieratome in the crystal lattice built that are either not enough or too many valence deliver, as energetically advantageous for the bond would be needed. Thus, in the semiconductor almost freely available to mobile carriers.

There are two types of doping

n-doping
These are by dumping of foreign atoms with excess negative valence charge in semiconductors. The vierwertigen element semiconductor silicon and germanium, for example, provides you with the pentavalent phosphorus. When the crystal is binding per Dotieratom So an electron is not needed, therefore, without great expenditure of energy throughout the crystal can be moved.
In this type of semiconductor called the electrons because they are the majority there are a majority carrier. The holes, but only by thermal stimulation can be created, read here minority carrier. Because of their tendency to electrons for the governing process Available, called the Dotieratome donors here.


Figure 8: n-doping using the example of Silicon

From the perspective of the theory of energy bands created in an n-doped semiconductor free carrier in the valence.

p-doping
In this case, a Dotierstoff used for the crystal binding providing too few electrons. The missing electron is called a hole. Even by this method, the semiconductor conductive, because the electrons from hopping from one hole to the next move cargo. Effectively, this corresponds to a shipment of holes as a positive charge.
For silicon and germanium to get in this case, for example Boron atoms in the crystal.
This refers to the holes as majority charge carriers, as they compared the electrons greatly outweigh the disadvantages. The used Dotieratome called acceptors, since they are responsible for the optimal binding electrons want to record.


Figure 9: p-doping on the example of Silicon

In the tapes speak of theory produced holes in the valence, which are analogous to electrons in the conduction band move, but positive charge.

To a marked change in the leadership qualities meet Dotierstoff very low concentrations (for many applications, a concentration of a 107 per Dotieratom semiconductor atoms).