We illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO2(70nm)/Si(30nm)/SiO2(70nm) multilayer and its spatial redistribution when annealing processes are performed. By Rutherford backscattering spectrometry and Z‐contrast transmission electron microscopy we found an As accumulation at the Si/SiO2 interfaces and at the Si grain boundaries with no segregation of the As in the Si layer.Such an effect is in agreement with a model that assumes a traps distribution in the Si in the first 2–3 nm above the SiO2/Si interfaces and along the Si grain boundaries. The traps concentration at the Si/SiO2 interfaces was estimated in 1014 traps/cm2. The outlined results can open perspectives on the doping properties of As in Si nanocrystals, whose applications in nanoelectronics and optoelectronics are widely investigated (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)