Recombination Processes in Insulators and Semiconductors

Abstract

The discrete states in the forbidden zone are divided into ground states and shallow trapping states. The major recombination traffic passes through the ground states. The shallow trapping states cause the observed decay time of free carrier concentrations to exceed the lifetime of a free carrier in the conduction (or valence) band. At low rates of excitation (free carrier concentrations less than ground state concentrations) the electron lifetime and hole lifetime are independent and, in general, significantly different. At high rates of excitation the free electron and hole lifetimes are equal. For an insulator having one class of ground states (a class being defined by the capture cross sections for electrons and holes) the high-light lifetime is bracketed by the two low-light lifetimes.