As a classical presentation of the management process, we have tried an image in which the electrons, so to speak, by analogy with balls in a crate or even how a classical particle in a gas container to be transported. The necessary quantum mechanical perspective can be but the underlying idea of a particle with a solid trajectory, the whereabouts of a particle at a time fixed columns, not to be. Instead blurred the locations under the theory of quantum mechanics in a range of possible whereabouts. The timing of this change in areas where the particles can be stopped, with formalism, the description of waves eg in the classical wave optics are known. It must be in our case the influence of the lattice ions are taken into account.

In a single atom is an electron by the attractive effect of the nucleus caught. The quantum mechanical result is, as we have seen that the energy of the current movement no longer accept any values - that it is quantized (link to this chapter: The atom).
The electrons over a whole crystal move may base their movement through a wide range of energies accept any. The influence of the ion lattice effect, however, that there are areas of energy, the particles can not reach. That is an opinion inaccessible for our result. It means that the particles can be accelerated so that their energy in such a prohibited area.

In a diagram, the possible electron energies describes, there is so-called forbidden and allowed bands, the theory here described its name (see Figure 7). The location and width of energy bands is limited by the crystal structure of the solid. For his decisive leadership qualities, which energy sectors by the electrons may be reduced.


Figure 7: The situation of the energy bands for various materials

With this knowledge can be a more accurate classification of non-conductors, semiconductors and conductors.

Not head: Here, the electron energies of up to a prohibited area heranreichen (called the energy band below the valence prohibited area, the higher conduction band). These electrons can therefore not arbitrarily be accelerated as the flow of electric Innervate necessary. This would require them only with the necessary energy supply in the upper range permitted (in the conduction band). Only then would the management process is available. As for non-heads of this energy difference is very large, you can also increase the melting temperature until no significant number of cargo carriers.

In a semiconductor, however, is the forbidden energy sector so small that thermal energy is sufficient to electrons into the conduction band levels. Valence remains in a hole.

When a metal are virtually no available electrons, whose energy close to a forbidden energy sector. There are so many electrons, whose energy can be adjusted continuously, so arbitrarily by the crystal can be speeded up.