Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order to enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs) have become the main building block of silicon photonic (modulators, waveguide, source, and detectors). In this work, we present an approach based on implantation of Ag (or Au) ions and a proper thermal annealing in order to improve the photoluminescence (PL) emission of Si-NCs embedded in SiO2. The Si-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2？μm under surface). Once Si-NCs are formed inside the SiO2 we implant metal ions at energies that do not damage the Si-NCs. We have observed by, PL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere could significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with an enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances the hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs. 1. Introduction Despite the great effort made in silicon photonics to achieve efficient Silicon Nanocrystals (Si-NCs), light emitters embedded in a solid silicon dioxide (SiO2) matrix, the photoluminescence (PL) from that kind of devices continues to be too weak for many practical applications [1]. The reason for that resides in two principal aspects: one of them is the well-known quasi-direct band gap in silicon nanocrystals which reduces the probability for radiative transition [1–3], and the other is related to the fact that PL properties of Si-NCs are strongly affected by their surface defects [4, 5]. The Pb defects, or dangling bonds, are known to cause quenching of the PL from Si-NCs [4–6]. Much research has been done to find a method to enhance the PL emission from a system of Si-NCs in SiO2 by controlling the passivation of their surface defects by using gases such as hydrogen (H2), nitrogen (N2), or oxygen (O2) [7–14]. It is well known that a thermal treatment in a molecular hydrogen-containing atmosphere increases the PL from Si-NCs more than Nitrogen or Oxygen [7]. This could be related to the fact that hydrogen diffusion in silica is higher, and consequently a great number of surface defects can be passivated. In many pieces of work the Si-NCs are formed by ion implantation at energies between 35 and
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