The temperature dependence of radiative and nonradiative processes at Er-Ocenters in Si

Er-doped silicon is a promising material for silicon microphotonics light s ources. Luminescence from Er-O centers in silicon exhibits an intensity que nching as the temperature is raised from 4 to 300K. We present the first un ified description of the excitation and de-excitation processes over the en tire temperature range. We model the phenomena in terms of exciton Auger, i mpurity Auger, and multiphonon transition processes. A set of rate equation s that includes all of these processes is written to describe the energy tr ansfer, and the normalized luminescence intensity versus temperature is com puted and compared to experimental data. The proposed model fits the experi mental photoluminescence data over the entire temperature range. Junction p hotocurrent spectroscopy measurements confirm the presence of a non-radiati ve multiphonon backtransfer mechanism. The photocurrent generated from the direct optical excitation of Er centers was found to increase with temperat ure in the form expected from the energy backtransfer model. (C) 1999 Elsev ier Science B.V. All rights reserved.