Memory characteristics of Al nanocrystals embedded in Al₂O₃ layers

The capacitance characteristics of aluminum nanocrystal-embedded metal-oxide-semiconductor (MOS) capacitors with gate layers composed of Al₂O₃ layers are investigated in this work. The capacitance versus voltage (C-V) curves obtained from a representative MOS capacitor embedded with aluminum nanocrystals synthesized by the thermal treatment process exhibit the window of flat-band voltage shift, which indicates the presence of charge storages in the aluminum nanocrystals. Their hysteresis curves are dependent on the range of sweep voltage. The counterclockwise hysteresis and leftward shift of the flat-band voltages observed from the C-V curves signify that electrons are trapped in a floating gate layer consisting of the aluminum nanocrystals present between two Al₂O₃ layers in the MOS capacitor, and that these trapped electrons originate from the p-type Si substrate.