Fabrication of Sn@Al₂O₃ Core-shell Nanoparticles for Stable Nonvolatile Memory Applications

Sn@Al₂O₃ core-shell nanoparticles (NPs) with narrow spatial distributions were synthesized in silicon dioxide (SiO₂). These Sn@Al₂O₃ core-shell NPs were self-assembled by thermally annealing a stacked structure of SiO_x/Al/Sn/Al/SiO_x sandwiched between two SiO₂ layers at low temperatures. The resultant structure provided a well-defined Sn NP floating gate with a SiO₂/Al₂O₃ dielectric stacked tunneling barrier. Capacitance-voltage (C-V) measurements on a metal-oxide-semiconductor (MOS) capacitor with a Sn@Al₂O₃ core-shell NP floating gate confirmed an ultra-high charge storage stability, and the multiple trapping of electron at the NPs, as expected from low-k/high-k dielectric stacked tunneling layers and metallic NPs, respectively.