In this work the site of Er ions in a silica matrix containing Si nanoclusters (nc) is investigated. The Er ions are introduced into a silica matrix containing Si nanoclusters by ion implantation. The X-ray absorption spectroscopy (EXAFS), performed at Er LIII-edge shows that the Er site in the matrix strongly depends on the preparation conditions; the effect of the implantation dose on the local structure around Er is addressed. The data demonstrate that the Er atoms are surrounded in the first shell by O atoms. Moreover, an increasing in the Er implantation dose implies an increase of the number of O atoms in the first shell and of their distance to the Er central atom, leading to the formation of a Er site more similar to that of bulk Er2O3.