Optimized Resistive Switching in TiO₂ Nanotubes by Modulation of Oxygen Vacancy Through Chemical Reduction

• Published in: IEEE transactions on electron devices 2020-05, Vol.67 (5), p.1-8
• Main Authors: Hazra, Arnab, Jan, Atif, Tripathi, Ashutosh, Kundu, Souvik, Boppidi, Pavan Kumar Reddy, Gangopadhyay, Subhashis
• Format: Article
• Language: English
• Subjects: Anodizing; Arrays; Chemical reduction; Crystallography; Electric potential; Electrodes; Electroforming; Endurance; Hydrazines; Metal oxides; Nanotubes; Oxidation; Oxygen; oxygen vacancy modulation; Photoelectrons; Photoluminescence; Random access memory; resistive switching; Substrates; Switching; TiO₂ nanotubes; Titanium; Titanium dioxide; Vacancies; Voltage
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2020.2983755

The resistive switching behavior of 1-D TiO₂ nanotube-based resistive random access memory (ReRAM) is discussed in this article. Highly oriented TiO₂ nanotubes were synthesized by anodic oxidation method on a Ti substrate, which was used as the bottom electrode. To modulate the oxygen vacancy (VO) in TiO₂ nanotubes, hydrazine hydrate reduction was employed in the temperature range 60°C-100°C. After charactering the morphological, elemental, and crystallographic properties, the level of reduction in different TiO₂ nanotubes array was estimated by Raman, photoluminescence, and X-ray photoelectron spectroscopies. Au/TiO₂ nanotubes/Ti devices were fabricated by using TiO₂ nanotubes with various levels of reductions where thin and porous Au top electrode was used to make the resistive switching faster. TiO₂ Nanotubes array, reduced at 80°C showed promising resistive switching performance with SET/RESET voltages of 2 V/1.8 V, Roff/Ron of 19 at a read voltage of 0.5 V (25°C) and stable endurance behavior after the 100th cycle. Interestingly, reduction temperature at 60°C and 100°C, offered degraded resistive switching within the same voltage range. All the devices showed electroforming free bipolar resistive switching. Efforts were devoted to establish the role of VO and its tuning to improve the resistive switching behavior in 1-D TiO₂ nanotubes. This article systematically showcases the efficacy of 1-D metal oxide for potential ReRAM application and establishes an easy but efficient approach to improve the resistive switching by modulating oxygen vacancy in it.