Facile Approach for Improving Synaptic Modulation of Analog Resistive Characteristics by Embedding Oxygen Vacancies‐Rich Sub‐TaOx in Pt/Ta2O5/Ti Device Stacks

Abstract

Herein, a Ta2O5‐based resistive synaptic device with high symmetricity and enhanced switching ratio is successfully obtained by the formation of sub‐TaO x with enriched oxygen vacancies into Ta2O5 switching layers. The concentration of Ta nanoclusters in Ta2O5 can be precisely controlled using plasma‐enhanced atomic layer deposition (PE‐ALD), where the number of cycles is varied from 5 to 20 cycles with steps of five cycles. The as‐fabricated Ta2O5 resistive synaptic device containing Ta deposited using five cycles exhibits increased switching window and switching current. As a result, the linearity of potentiation/depression improves significantly from 13.53/−16.83 to 4.45/−1.38 by applying successive programing pulses, indicating that the recognition accuracy of the Mixed National Institute of Standards and Technology pattern is increased by 11.45% compared with the pristine device. It is considered that the introduction of an optimal number of Ta deposition cycles can effectively control the porosity of the Ta2O5 layer, resulting in an increase in the movement of oxygen ions and analog switching behavior. Thus, a facile PE‐ALD technique can be applied to demonstrate highly reliable analog synaptic devices for neuromorphic hardware systems.