Charge storage characteristics of atomic layer deposited $RuOx$ nanocrystals

The charge storage characteristics of atomic layer deposited $RuOx$ nanocrystals embedded in high-$k$ $HfO2∕Al2O3$ films in a metal/$Al2O3∕RuOx∕HfO2∕SiO2∕n-Si$ structure have been investigated. The size and density of $RuOx$ nanocrystals have been measured using transmission electron microscopy. The $RuOx$ nanocrystals show a density of $∼1×1012∕cm2$ and a diameter of $5–8nm$⁠. A large hysteresis memory window of $∼13.3V$ at a gate voltage of $9V$ has been observed for $RuOx$ nanocrystal memory capacitors. A hysteresis memory window of $0.7V$ has also been observed under a small sweeping gate voltage of $1V$⁠. A promising memory window of $RuOx$ nanocrystals has been observed as compared with those of pure $HfO2$ and $Al2O3$ charge trapping layers, due to charge storage in the $RuOx$ metal nanocrystals. The $RuOx$ nanocrystal memory capacitor has similar leakage current with the pure $HfO2$ and $Al2O3$ charge trapping layers. The $RuOx$ memory capacitor has a large breakdown voltage of $∼13.8V$⁠.