Recombination at semiconductor surfaces and interfaces

Abstract

The present state of understanding of recent work on recombination processes at semiconductor surfaces and interfaces is assessed. The derivation of the phenomenological Stevenson-Keyes expression is outlined to indicate basic mechanisms and assumptions and to provide the theoretical framework for interpreting recombination data. Trends in recombination velocities with bulk doping are shown to be an important diagnostic tool in the absence of explicit information about the surface Fermi level. The significantly greater photoluminescent efficiency of InP relative to GaAs, the improvement of photoluminescent efficiencies in GaAs by Ru treatment, and the sensitivity of the photoluminescent efficiencies of InP are all shown to be consistent with changes in the position of the surface Fermi level within the Spicer unified defect model, although alternative explanations are also possible. In general, independent measurements of the surface Fermi level by, e.g., surface photovoltage measurements could provide the necessary information to decide among alternative interpretations.