An insight into the dopant selection for CeO2-based resistive-switching memory system: a DFT and experimental study

Fayyaz Hussain, Muhammad Imran, Anwar Manzoor Rana, R. M.Arif Khalil, Ejaz Ahmad Khera, Saira Kiran, M. Arshad Javid, M. Atif Sattar, Muhammad Ismail

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The aim of this study is to figure out better metal dopants for CeO2 for designing highly efficient non-volatile memory (NVM) devices. The present DFT work involves four different metals doped interstitially and substitutionally in CeO2 thin films. First principle calculations involve electron density of states (DOS) and partial density of states (PDOS), and isosurface charge densities are carried out within the plane-wave density functional theory using GGA and GGA + U approach by employing the Vienna ab initio simulation package VASP. Isosurface charge density plots confirmed that interstitial doping of Zr and Ti metals truly assists in generating conduction filaments (CFs), while substitutional doping of these metals cannot do so. Substitutional doping of W may contribute in generating CFs in CeO2 directly, but its interstitial doping improves conductivity of CeO2. However, Ni-dopant is capable of directly generating CFs both as substitutional and interstitial dopants in ceria. Such a capability of Ni appears acting as top electrode in Ni/CeO2/Pt memory devices, but its RS behavior is not so good. On inserting Zr layer to make Ni/Zr:CeO2/Pt memory stacks, Ni does not contribute in RS characteristics, but Zr plays a vital role in forming CFs by creating oxygen vacancies and forming ZrO2 interfacial layer. Therefore, Zr-doped devices exhibit high-resistance ratio of ~ 104 and good endurance as compared to undoped devices suitable for RRAM applications.

Original languageEnglish
Pages (from-to)839-851
Number of pages13
JournalApplied Nanoscience (Switzerland)
Volume8
Issue number4
DOIs
StatePublished - 1 Apr 2018

Keywords

  • CERIA
  • Charge density
  • Density functional theory
  • Doping
  • Resistive switching

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