Excellent resistive switching properties of atomic layer-deposited Al(2)O(3)/HfO(2)/Al(2)O(3) trilayer structures for non-volatile memory applications

We have demonstrated a flexible resistive random access memory unit with trilayer structure by atomic layer deposition (ALD). The device unit is composed of Al(2)O(3)/HfO(2)/Al(2)O(3)-based functional stacks on TiN-coated Si substrate. The cross-sectional HRTEM image and XPS depth profile of Al(2)O(3)/HfO(2)/Al(2)O(3) on TiN-coated Si confirm the existence of interfacial layers between trilayer structures of Al(2)O(3)/HfO(2)/Al(2)O(3) after 600°C post-annealing. The memory units of Pt/Al(2)O(3)/HfO(2)/Al(2)O(3)/TiN/Si exhibit a typical bipolar, reliable, and reproducible resistive switching behavior, such as stable resistance ratio (>10) of OFF/ON states, sharp distribution of set and reset voltages, better switching endurance up to 10(3) cycles, and longer data retention at 85°C over 10 years. The possible switching mechanism of trilayer structure of Al(2)O(3)/HfO(2)/Al(2)O(3) has been proposed. The trilayer structure device units of Al(2)O(3)/HfO(2)/Al(2)O(3) on TiN-coated Si prepared by ALD may be a potential candidate for oxide-based resistive random access memory.