Photoluminescence from Si-capped GeSn nanodots on Si substrates formed using an ultrathin SiO_2 film technique

摘要

We observed strong 1.5 μm photoluminescence (PL) from Si-capped Ge_(1-x)Sn_x nanodots on Si (001) substrates formed using ultrathin SiO_2 films. The lack of the quantum size effect in the PL revealed that the PL came from Si capping layers with radiative defects and not from the nanodots. The PL intensities were strongly enhanced when the Sn composition x increased in Ge_(1-x)Sn_x nanodots or the nanodot size decreased. These results indicate that the formation of the radiative defects in Si is strongly correlated with the nanodot structures such as its geometry and strain states. This study demonstrates a new formation technique for light-emitting Si structures with high controllability and compatibility with Si technology.