Improved resistive switching characteristics by O2 plasma treatment in bi-layer Ti/ZnO/OPT-ZnO/ITO RRAM

• Published in: Current applied physics Vol. 49; pp. 120 - 126
• Main Authors: Jeong, Hyeyeon, Shin, Jeongmin, Kim, Saeyoung, Pak, James J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2023
• Subjects: Embedded layer; Oxygen plasma treatment; Resistive switching; Ti/ZnO/ITO RRAM; Embedded layer; Oxygen plasma treatment; Ti/ZnO/ITO RRAM; Resistive switching
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2023.03.001

This paper presents the effect of oxygen plasma process to the ZnO switching layer of Ti/ZnO/ITO resistive random access memory (RRAM). ZnO thin film was formed by spin-coating of the precursor solution and oxygen plasma process was carried out in three different cases: Case 1) Single ZnO film with no oxygen plasma treatment; Case 2) Single ZnO film with oxygen plasma treatment on the top; Case 3) Two ZnO layers and oxygen plasma treatment on the bottom layer. The best resistive switching characteristics were obtained from the case 3) with stable endurance over 1000 DC cycles and stable retention up to 104 s, while the case 2) showed better endurance cycle (∼350 cycles) than that (<100) of the case 1). This result may be attributed to the prevention of oxygen ion absorption of Ti layer. XPS analysis indicates that the oxygen plasma process increases the oxygen contents in ZnO film, increasing metal-oxygen bonds and reducing the oxygen vacancies. •Oxygen plasma treatment modifies the oxygen contents in the ZnO switching layer and reduces the number of oxygen vacancies.•Some of extra additional oxygen ions in the upper part of the OPT-ZnO film are absorbed by Ti metal.•When the oxygen ion contents are reduced in the switching layer of the RRAM, the RESET process cannot happen normally.