Charge storage characteristics of atomic layer deposited RuOx nanocrystals

Abstract

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.