The photoluminescence mechanism of erbium in silicon: intensity dependence on excitation power and temperature

Abstract

The photoluminescence intensity of erbium in silicon was measured as a function of laser excitation power and temperature. Results of these measurements are described on the basis of a physical model which includes the formation of free excitons, the binding of excitons to erbium ions, excitation of 4f-shell electrons of erbium ions and decay of excited erbium ions by light emission. An Auger energy transfer to free carriers by both erbium-bound excitons and excited erbium ions must be included in the model in order to obtain a quantitative agreement with experiment. From the temperature dependence two activation energies are derived, which are associated with the binding of excitons to erbium centers and with an energy transfer process from excited erbium ions back to erbium-bound excitons, respectively. The luminescence properties of the different types of Er-doped crystalline silicon are remarkably similar.