7.3 Bandstructure of Metals and Semiconductors
Metals
In a metal there are a bunch of bands that are electrically inert. They are occupied by electrons
but far away from the fermi energy so that the electrons do not participate in the properties of the
metal (conductivity, specific heat). Hence they are calledinert bands. Bands way above the fermi
energy are just empty and electrically inactive too. The interesting band is the one that is partly
filled. The electrons at this level will contribute to the magnetism, the heat capacity, the electrical
conductivity and the thermal conductivity of the material. Fig. 45 is drawn for about room tempera-
ture. At room temperaturekBT(the thermal energy) tends to be much smaller than the fermi energy
and the fermi function is pretty sharp.
Figure 45: Bands in a metal.