Enhancement of Resistive and Synaptic Characteristics in Tantalum Oxide-Based RRAM by Nitrogen Doping

Resistive random-access memory (RRAM) for neuromorphic systems has received significant attention because of its advantages, such as low power consumption, high-density structure, and high-speed switching. However, variability occurs because of the stochastic nature of conductive filaments (CFs), producing inaccurate results in neuromorphic systems. In this article, we fabricated nitrogen-doped tantalum oxide (TaO_x:N)-based resistive switching (RS) memory. The TaO_x:N-based device significantly enhanced the RS characteristics compared with a TaO_x-based device in terms of resistance variability. It achieved lower device-to-device variability in both low-resistance state (LRS) and high-resistance state (HRS), 8.7% and 48.3% rather than undoped device of 35% and 60.7%. Furthermore, the N-doped device showed a centralized set distribution with a 9.4% variability, while the undoped device exhibited a wider distribution with a 17.2% variability. Concerning pulse endurance, nitrogen doping prevented durability from being degraded. Finally, for synaptic properties, the potentiation and depression of the TaO_x:N-based device exhibited a more stable cycle-to-cycle variability of 4.9%, compared with only 13.7% for the TaO_x-based device. The proposed nitrogen-doped device is more suitable for neuromorphic systems because, unlike the undoped device, uniformity of conductance can be obtained.