Photoluminescence of erbium-doped silicon: Excitation power dependence

The intensity of the photoluminescence of erbium in silicon is analyzed by a model which takes into account the formation of free excitons, the binding of excitons to erbium ions, the excitation of inner-shell 4f electrons of erbium ions and their subsequent decay by light emission. Predictions of this model for the dependence of luminescence intensity on laser excitation power are compared with experimental observations. The results for float-zone and Czochralski-grown silicon, in which erbium is introduced by implantation with or without oxygen co-implantation, are remarkably similar. To obtain agreement between model analysis and experimental data it is necessary to include in the model terms describing energy dissipation by an Auger process of both the erbium-bound excitons and the erbium ions in excited state with free electrons in the conduction band. A good quantitative agreement is achieved.