The exploitation of Si nano structures for electronic and optoelectronic devices depends on their electronic doping. We investigate a methodology for As doping of Si nano structures taking advantages of ion beam implantation and nanosecond laser irradiation melting dynamics. We illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO{sub 2}/Si/SiO{sub 2} multilayer and its spatial redistribution after annealing processes. As accumulation at the Si/SiO{sub 2} interfaces was observed by Rutherford backscattering spectrometry in agreement with a model that assumes a traps distribution in the Si in the first 2-3 nm above the SiO{sub 2}/Si interfaces. A concentration of 1014 traps/cm{sup 2} has been evaluated. This result opens perspectives for As doping of Si nano clusters embedded in SiO{sub 2} since a Si nano cluster of radius 1?nm embedded in SiO{sub 2} should trap 13 As atoms at the interface. In order to promote the As incorporation in the nano clusters for an effective doping, an approach based on ion implantation and nanosecond laser irradiation was investigated. Si nano clusters were produced in SiO{sub 2} layer. After As ion implantation and nanosecond laser irradiation, spectroscopic ellipsometry measurements show nano clusters optical properties consistent with their effective doping. scanning transmission electron microscopy