Toward long-term retention-time single-electron-memory devices based on nitrided nanocrystalline silicon dots

A memory capacitor with a structure of Si-SiO₂/nc-Si dots/silicon nitride films/SiO₂ was prepared by means of nc-Si dot deposition followed by N₂ plasma nitridation processes. The memory device offers dual memory nodes: nc-Si dots and traps in silicon-nitride films. An enlarged memory window in CV characteristics was observed in memory operations, due to the extra traps in silicon-nitrides. The charge-loss rate was found to be much smaller than that of single memory nodes using nc-Si dots only. The provided larger memory window (about twice the width) and longer retention time in the memory operations (three orders of magnitude) are discussed in terms of trap-assisted charging/discharging mechanisms.