The effect of ion beams on the formation of Si nanoclusters from a-SiOx films and their luminescenceproperties is investigated. a-SiOx films with Sicontent ranging from 33 to 50 at. % were deposited by Electron CyclotronResonance Plasma Enhanced Chemical Vapor Deposition (ECR-PECVD) of SiH4 and O2. Prior to anneal, some samples wereimplanted with 380 keV Si to a dose ranging from 5.7 × 1014 cm−2 to 5.7 × 1016 cm−2. All films wererapid thermal annealed under flowing Ar environment, and hydrogenated afteranneals to passivate defects and to enhance the luminescence of Sinanoclusters. For films with Si content less than 40 at. %, ion beamslightly reduces the photoluminescence (PL) intensity and induces a slightblueshift of the luminescence. For films with Si content greater than 40 at.%, ion beam greatly increases the PL intensity. Based on the effect of theion beams dose and the ion specie, we propose that ion beams damage greatlypromotes nucleation of small Si clusters from the a-SiOx matrix.