Time-resolved investigation of the mid-infrared-induced enhancement of Er³⁺ emission in Si

Previously, we reported on the enhancement of Er photoluminescence (PL) in silicon upon mid-infrared (MIR) laser pulse fired at certain delay with respect to Nd:YAG pulsed primary excitation. This effect was explained as the ionization of traps by the MIR beam. The shallow nature of the traps was concluded from its temperature and wavelength dependence. In this contribution, we have studied temporal characteristics of the enhancement effect as a function of the delay time between the two pulses. Decay kinetics of erbium PL measured at 4K was found to show two different time constants of 1ms (fast) and 26ms (slow). A correlation between the enhancement effect and the amplitude of the slow component of the Er PL has been observed. We also have noticed that the enhancement of Er emission is accompanied by subsequent quenching of the slow component, indicating redistribution of energy in the system. Based on the study, we conclude that MIR laser ionizes non-equilibrium traps whose thermalization is responsible for the slow component of the Er PL. © 2001 Elsevier Science B.V. All rights reserved.