Electrical properties of Si nanocrystals capped with SiO2/Si3N4 for non-volatile memory

Electrical properties of Si nanocrystals (NCs) were analyzed with respect to the shell formation of NCs. The Si nanocrystal samples produced by pyrolysis and laser ablation methods were followed by sharpening oxidation steps. In these steps Si NCs are capped with a thin oxide or nitride layer of 1-2nm thickness for isolation and the size control. It also affects the interface states of NCs, resulting in the change of electrical properties. To clarify this effect, conventional C-V, I-V and charge retention time measurements were performed on a MOS capacitor structure. Using scanning probe microscopy (SPM), we observed local properties of a capped Si nanocrystal. These results were analyzed for the size, density and shell materials of NCs. We also measured the temperature dependence of electrical properties of Si NCs.