Charge storage in self-aligned doubly stacked Si nanocrystals in SiNx dielectric

Doubly stacked layers of silicon nanocrystals (nc-Si) in amorphous silicon nitride (α-SiNx) dielectric have been fabricated by plasma enhanced chemical vapor deposition and subsequent high-temperature thermal annealing. Capacitance-voltage (C-V) and current-voltage (I-V) measurements were used to investigate its charge trapping phenomena and confirmed the memory effects of the nc-Si, which exhibited capacitance hysteresis and asymmetric current peaks, respectively. This structure has realized a two-level charge storage by Fowler-Nordheim tunneling in high-field regime. While under low field, the resonant tunneling of holes into stacked nc-Si was responsible for current peaks. The transport property of stacked nc-Si was discussed and a model was put forward to explain the retention mechanism.