Three-dimensional simulation of nanocrystal Flash memories

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Abstract
We have developed a code for the detailed simulation of nanocrystal Flash memories, which consist of metal–oxide–semiconductor field-effect transistors �MOSFETs � with an array of semiconductor nanocrystals embedded in the gate dielectric. Information is encoded in the MOSFET threshold voltage, which depends on the amount of charge stored in the nanocrystal layer. Nanocrystals are charged through direct tunneling of electrons from the channel. Such memories are promising in terms of shorter write–erase times, larger cyclability, and lower power consumption with respect to conventional nonvolatile memories. We show results obtained from the self-consistent solution of the Poisson–Schrödinger equation on a three-dimensional grid, focusing on the charging process and on the effect of charge stored in the nanocrystals on the threshold voltage. © 2001 American Institute of Physics. �DOI: 10.1063/1.1361097� A nanocrystal Flash memory is basically a metal– oxide–semiconductor field-effect transistor �MOSFET � in which the gate dielectric is replaced by a gate stack consisting of a thin tunneling oxide, a layer of semiconductor nanocrystals embedded in silicon oxide, and a thicker oxide