The influence of doping on the photoluminescence of a system consisting of silicon nanocrystals in silicon dioxide matrix is analyzed. The nanocrystals were grown by annealing of a silicon dioxide deposited with an excess of silicon and then passivated in a Forming Gas atmosphere. The doping of the nanocrystals with boron and arsenic was made by ion implantation. The composition of the samples was determined by Rutherford Backscattering Spectrometry and a structural characterization of the nanocrystals was done by Transmission Electron Microscopy. The influence of different thermal treatments used to grow and to passivate the nanocrystals is compared and a discussion for the possible explanation for the discrepancy in the results is presented. The highest photoluminescence intensity was achieved by arsenic doped silicon nanocrystals.