Photoluminescence (PL) spectroscopy has been demonstrated as a suitable technique to characterize Si nanocrystal-based non-volatile memory devices (Carrada et al. APL 2005). These are formed by a single plane of Si nanocrystals (NCs) buried in the gate oxide of a MOS device, at a tunneling distance from the channel. Such a 2D array was obtained by low-energy ion implantation followed by annealing. It was shown that the electrical properties are dramatically improved after annealing in oxidizing conditions. These necessary conditions for oxide healing also lead to a strong increase of the PL intensity as well as to a good agreement between the PL energies and the NCs sizes measured by electron microscopy (Bonafos et al., Solid State Electr. 2005). Recently, both these elaboration and characterization techniques were extended to the production and the study of new nano-scale electronic devices which exploit the Coulomb blockade effect and other quantized charging features at 300 K (Shalchian et al., APL 2005). The fabrication of such devices requires the fine control of a small number of NCs of about 3 nm in diameter, ideally down of the single particle. This can be achieved by 1 keV Si-implantation through stencil masks with window sizes ranging from 300*300 nm2 to 1*3 micron2. After mask removal and annealing, PL spectroscopic imaging under a confocal microscope is used to detect the NCs rich areas. The image of the PL intensity is found to mimic the mask geometry. Moreover, a blueshift of the PL energy is detected in the same image near the edges of the mask holes. This blueshift is probably due to the smaller sizes of Si-NCs near the mask edge. Energy filtered transmission electron microscopy is underway to assess and study this size distribution.