In quantum flash memories, the floating gate is a nanocrystal (NC) layer which can be charged from the channel. To our knowledge, no attempt has been carried out to evaluate the interactions between nanocrystals inside a layer. On the contrary, since the NCs are commonly supposed to be independent, reduced systems of single NC are often considered. In our model and simulations, we show that the NC charging is not only related to relevant thicknesses (tunnel, oxide) and NC radii, but also to the electrostatic coupling that exists between two nanocrystals inside the floating gate layer. (c) 2006 Elsevier Ltd. All rights reserved.