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

Er-doped silicon is a promising material for silicon microphotonics light sources. Luminescence from Er-O centers in silicon exhibits an intensity quenching as the temperature is raised from 4 to 300K. We present the first unified description of the excitation and de-excitation processes over the entire temperature range. We model the phenomena in terms of exciton Auger, impurity Auger, and multiphonon transition processes. A set of rate equations that includes all of these processes is written to describe the energy transfer, and the normalized luminescence intensity versus temperature is computed and compared to experimental data. The proposed model fits the experimental photoluminescence data over the entire temperature range. Junction photocurrent spectroscopy measurements confirm the presence of a non-radiative multiphonon backtransfer mechanism. The photocurrent generated from the direct optical excitation of Er centers was found to increase with temperature in the form expected from the energy backtransfer model. (C) 1999 Elsevier Science B.V. All rights reserved.