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The role of nitrogen doping in ALD Ta2O5 and its influence on multilevel cell switching in RRAM

Sedghi, N and Li, H and Brunell, IF and Dawson, K and Potter, RJ and Guo, Y and Gibbon, JT and Dhanak, VR and Zhang, W and Zhang, JF and Robertson, J and Hall, S and Chalker, PR (2017) The role of nitrogen doping in ALD Ta2O5 and its influence on multilevel cell switching in RRAM. Applied Physics Letters, 110 (10). ISSN 0003-6951

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Abstract

The role of nitrogen doping on the stability and memory window of resistive state switching in N-doped Ta2O5 deposited by atomic layer deposition is elucidated. Nitrogen incorporation increases the stability of resistive memory states which is attributed to neutralization of electronic defect levels associated with oxygen vacancies. The density functional simulation with screened exchange hybrid functional approximation finds that the incorporation of nitrogen dopant atoms in the oxide network removes the O vacancy midgap defect states, thus nullifying excess defects and eliminating alternative conductive paths. By effectively reducing the density of vacancy-induced defect states through N doping, 3-bit multilevel cell switching is demonstrated, consisting of eight distinctive resistive memory states achieved by either controlling the set current compliance or the maximum voltage during reset. Nitrogen doping has a threefold effect; widening the switching memory window to accommodate more intermediate states, improving the stability of states, and providing gradual reset for multi-level cell switching during reset. The N-doped Ta2O5 devices have relatively small set and reset voltages (< 1 V) with reduced variability due to doping.

Item Type: Article
Uncontrolled Keywords: 09 Engineering, 02 Physical Sciences
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Q Science > QD Chemistry
T Technology > TK Electrical engineering. Electronics. Nuclear engineering
Divisions: Electronics and Electrical Engineering
Publisher: AIP Publishing
Date Deposited: 07 Mar 2017 10:12
Last Modified: 08 Sep 2017 06:20
DOI or Identification number: 10.1063/1.4978033
URI: http://researchonline.ljmu.ac.uk/id/eprint/5772

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