The Demonstration of Increased Selectivity during Experimental Measurement in Filament-Type Vanadium Oxide-Based Selector

Chun Kuei Chen, Chih Yang Lin, Po Hsun Chen, Ting Chang Chang, Chih Cheng Shih, Yi Ting Tseng, Hao Xuan Zheng, Ying Chen Chen, Yao Feng Chang, Chun Chu Lin, Hui Chun Huang, Wei Chen Huang, Hao Wang, Simon M. Sze

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


In this paper, vanadium oxide (VOx) was chosen for the resistive switching layer in a typical resistive random access memory (RRAM) structure. During negative forming bias, we found an initial selector property. This indicates the presence of metal-insulator-transition characteristics in the VOx layer even without an annealing process. In order to study this phenomenon, material analyses were conducted, with results indicating that there are V-O stretching bonds and an oxide/vanadium ratio of nearly 2.2 (O/V = 2.2). In addition, the experimental results of the dc sweeping test indicated that off-state current gradually decreased after each cycle, meaning that the selectivity characteristics in the VOx selector could be improved. Endurance performance of our experimental devices reached 108, sufficient for integration with RRAM devices in a 1S1R array. To further investigate this special phenomenon, current fitting analysis and simulation analyses were conducted. The results of the fitting analysis indicated that the conduction mechanism for off-state current was Schottky emission and the Schottky distance increased with increasing numbers of cycles. In other words, oxide ions migrate toward the filament at low negative voltage during dc sweeping, causing the formation of VOx. Furthermore, the results of thermal field simulation analysis indicated that there is a thermal concentration effect in and around the filament. Thus, oxide ions more easily migrate toward the vanadium filament when a stronger electrical field is present around the filament during dc sweeping cycles. Finally, stable vanadium selector characteristics are obtained and a conduction filament behavior model is proposed.

Original languageEnglish (US)
Article number8443118
Pages (from-to)4622-4627
Number of pages6
JournalIEEE Transactions on Electron Devices
Issue number10
StatePublished - Oct 2018
Externally publishedYes


  • Electric fields
  • metal-insulator transition (MIT)
  • selectivity
  • selector
  • thermal fields
  • vanadium oxide (VOx)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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