Ionization Interaction between Impurities in Semiconductors and Insulators

Abstract

It is known that the free energy of an imperfect semiconductor or insulator crystal contains terms which arise from the ionizability of these imperfections and which represent chemical interactions between imperfections of the same and different kinds. We show that these ionization terms, which involve the Fermi level and the parameters of the energy band model, explain the systematic differences between $n$- and $p$-type semiconductors in lattice vacancy concentration, in substitutional atom diffusion coefficients, and in amphoteric impurity behavior. The ionization terms also explain the variation of solid-liquid impurity distribution coefficients with the crystal growth rate of certain semiconductors, and also the well-known "charge balance" effect in insulators.