Photoluminescence characterization of few-nanocrystals electronic devices
Photoluminescence (PL) spectroscopy is demonstrated as a suitable technique to characterize silicon nanocrystals (Si-NCs)-based nonvolatile memory devices. The 2D array of Si-NCs forming the floating gate is obtained by low-energy ion implantation in thin oxide followed by annealing. The electrical properties and PL emission are dramatically improved after annealing in oxidizing conditions, which are necessary conditions for oxide healing. Both these elaboration and characterization techniques are currently extended to the production and the study of nanoscale electronic devices, which exploit the Coulomb blockade effect and other quantized charging features at 300 K. The fabrication of such devices requires the fine control of a small number of NCs of about 3 nm in diameter. This could be achieved by 1 keV Si-implantation through stencil masks with window sizes ranging from about 0.1 to 10 um2, with spacing between apertures in the 1–10 um range. 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. Some changes of the PL energy at maximum intensity are found, that could be attributed to different Si-NCs sizes.