Multi-Level Analog Resistive Switching Characteristics in Tri-Layer HfO/AlO/HfO Based Memristor on ITO Electrode.

Atomic layer deposited (ALD) HfO/AlO/HfO tri-layer resistive random access memory (RRAM) structure has been studied with a transparent indium tin oxide (ITO) transparent electrode. Highly stable and reliable multilevel conductance can be controlled by the set current compliance and reset stop voltage in bipolar resistive switching. Improved gradual resistive switching was achieved because of the interdiffusion in the HfO/AlO interface where tri-valent Al incorporates with HfO and produces HfAlO. The uniformity in bipolar resistive switching with I/I ratio (>10) and excellent endurance up to >10 cycles was achieved. Multilevel conductance levels in potentiation/depression were realized with constant amplitude pulse train and increasing pulse amplitude. Thus, tri-layer structure-based RRAM can be a potential candidate for the synaptic device in neuromorphic computing.