Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance

Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of...

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Bibliographic Details
Published in:Applied physics letters 2015-09, Vol.107 (12)
Main Authors: Dawson, J. A., Guo, Y., Robertson, J.
Format: Article
Language:English
Subjects:
Applied physics
Chemical potential
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Defects
DENSITY FUNCTIONAL METHOD
Density functional theory
ELECTRODES
ELECTRONIC STRUCTURE
ENERGY LEVELS
INTERSTITIALS
MEMORY DEVICES
Metal oxides
METALS
NICKEL OXIDES
Organic chemistry
OXYGEN
Random access memory
RECOMBINATION
VACANCIES
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Summary:Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4931751