Chemical Effects Due to the Ionization of Impurities in Semiconductors

This paper contains a theoretical account of the possible effects which the ionization of donor and acceptor impurities can induce in the thermodynamic phase relations involving their solutions with semiconductors. These effects reflect the energy band structure of the semiconductor. Furthermore, the phenomenon has an interest of its own, for within a certain range of experimental conditions the effects can be attributed to a chemical-like, mass action behavior of the electrons which play the roles of negative ions. Section V is a brief discussion of a fine point concerning the Fermi level. It is shown that although the Fermi level is certainly the electronic electrochemical potential, it is not the Gibbs free energy per electron unless the density of electron energy levels is linear in the volume of the system.