Published online by Cambridge University Press: 31 January 2011
Proposed mechanisms so far on defect reactions in semiconductors are reexamined. Structural instability of point defects is explained in terms of the Jahn-Teller effect. It is found that the tetrahedral coordinated bonds, which do not have inversion symmetry, are not so rigid as we consider, especially for hole localization. Second topic is the phonon-kick mechanism for defect reactions under carrier injection. In order to discuss this mechanism in detail, we recall the configuration coordinate (c-c) diagram, which is often misunderstood in the literature. The proper relation is explained among the lattice distortion, the position of the electronic level in the band gap (thermal and optical depths), the total energy the multiphonon (e and h) carrier capture processes and the following induced lattice relaxation. A numerical simulation has been performed on phonon kick mechanism. It is found that a rapid increase of the transient lattice vibration around the defect is possible and the probability critically depends on the carrier concentrations and the phonon frequency distribution.