Solar knowledge: As the temperature increases, the valence band electrons will jump into the conduction band due to heat, and the density of electrons increases exponentially according to Equation 2. This phenomenon can also be explained by the Fermi distribution.

The electrons can occupy "a dense position (state density: the number of states corresponding to unit energy) in each energy band of the valence band and the conduction band. The so-called Fermi distribution means that in the case of the thermodynamic temperature T, the electrons in the object reach thermal equilibrium. State, a law in which electrons occupy the energy of E. This law is called "Fermi energy level", which is called FM. This is a very special law. At absolute 0 degrees, when E is low In FM, the amount is occupied by electrons; when E is higher than FM, it is different and will not be occupied.