InAs nanocrystals on SiO2∕Si by molecular beam epitaxy for memory applications

We studied a memory structure based on InAs nanocrystals grown by molecular beam epitaxy directly on thermal SiO2 on silicon. Both nanocrystal diameter and density can be controlled by growth parameters. Transmission electron microscopy analysis shows high crystallinity and low size dispersion. In an electrical test structure with a 3.5nm tunnel oxide, we observed that 80% of the initial injected electrons remain stored in the InAs nanocrystals after 3months and that the retention time for electrons in InAs nanocrystals is four orders of magnitude higher than in silicon nanocrystals.