Low voltage operation of high-κ HfO₂/TiO ₂/Al₂O₃ single quantum well for nanoscale flash memory device applications

Memory characteristics of the high-κ HfO₂/TiO ₂/Al₂O₃ single quantum well in a p-Si/Al ₂O₃/HfO₂/TiO₂/Al₂O ₃/platinum capacitor structure have been investigated. All high-κ films have been deposited by atomic layer deposition. A significant memory window of ∼1.6V at a low gate voltage operation of 2V, a high charge storage density of ∼3.6 × 10¹²/cm², a moderate leakage current density of 1 × 10^-6/cm² at a gate voltage of -2V, and a negligible charge loss of <5% up to 10⁴ s of retention for the high-κ HfO₂/TiO₂/Al ₂O₃ single quantum well memory capacitor have been observed as compared with those of pure HfO₂, pure TiO₂, and pure Al₂O₃ charge trapping layers. Excellent memory characteristics of the high-κ HfO₂/TiO₂/Al ₂O₃ single quantum well device are obtained due to charge storage in the quantum well. The high-κ HfO₂/TiO ₂/Al₂O₃ quantum well device with a low gate voltage operation of <2 V can be used in future nanoscale flash memory device applications.