Threshold-voltage statistics and conduction regimes in nanocrystal memories

Results of three-dimensional Monte Carlo simulations of nanocrystal (NC) memory cells are presented to investigate the statistical properties of the threshold-voltage shift (ΔVT ). It is shown that NC-number fluctuations dominate the ΔVT spread in the ON-state cell conduction regime, while percolation effects add a significant contribution to the statistical spread in the subthreshold region. The dependence of theΔVT statistics on the cell geometry is also investigated, which shows that NC number and position fluctuations can strongly affect the memory performance and must be suitably modeled.