Synaptic Plasticity and Learning Behaviors Mimicked in Single Inorganic Synapses of Pt/HfO/ZnO/TiN Memristive System.

In this work, a kind of new memristor with the simple structure of Pt/HfO/ZnO/TiN was fabricated completely via combination of thermal-atomic layer deposition (TALD) and plasma-enhanced ALD (PEALD). The synaptic plasticity and learning behaviors of Pt/HfO/ZnO/TiN memristive system have been investigated deeply. Multilevel resistance states are obtained by varying the programming voltage amplitudes during the pulse cycling. The device conductance can be continuously increased or decreased from cycle to cycle with better endurance characteristics up to about 3 × 10 cycles. Several essential synaptic functions are simultaneously achieved in such a single double-layer of HfO/ZnO device, including nonlinear transmission properties, such as long-term plasticity (LTP), short-term plasticity (STP), and spike-timing-dependent plasticity. The transformation from STP to LTP induced by repetitive pulse stimulation is confirmed in Pt/HfO/ZnO/TiN memristive device. Above all, simple structure of Pt/HfO/ZnO/TiN by ALD technique is a kind of promising memristor device for applications in artificial neural network.