Theory of recombination-enhanced defect reactions in semiconductors

Abstract

We present a quantitative theory to describe enhancement of defect reaction rates upon electron-hole recombination. The theory is based on the following mechanism: energy liberated upon nonradiative electron or hole capture is converted largely into vibrational energy that is initially localized in the vicinity of the defect. This vibrational energy can be utilized to promote defect reactions such as diffusion. The process can be described using a formulation similar to the successful Rice-Ramsperger-Kassel theory of unimolecular reactions. The resulting expression for the enhanced reaction rate depends upon two physical properties of the defect: the number of effective oscillators of the "defect molecule" and the rate of dissipation of local vibrational energy to the lattice. The theory is consistent with recent experiments of Kimerling and Lang and may be useful for understanding several related processes occurring in semiconductors.