Photoluminescence dynamics and reduced Auger recombination in Si1-xGex/Si superlattices under high-density photoexcitation

Abstract

Optical gain and stimulated emission processes in Si nanostructures are controlled by the dynamics of high-density carriers. Here, we report photoluminescence (PL) dynamics and multiexciton recombination in Si1−xGex/Si superlattices (SLs) under high-density excitation. Saturation of the PL intensity and rapid PL decay are observed as the excitation laser intensity is increased. These phenomena occur due to nonradiative Auger recombination of the electron-hole pairs. We find that the Auger process in Si1−xGex/Si SLs is less pronounced than that in the Si1−xGex/Si single quantum wells. Our results show that coupled nanostructures have an advantage in efficient light emission and the control of many-body carrier dynamics.