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The role of nitrogen doping in ALD Ta<inf>2</inf>O<inf>5</inf>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, WD and Zhang, JF and Robertson, J and Hall, S and Chalker, PR (2017) The role of nitrogen doping in ALD Ta<inf>2</inf>O<inf>5</inf>and its influence on multilevel cell switching in RRAM. Applied Physics Letters, 110. ISSN 0003-6951

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Abstract

© 2017 Author(s). The role of nitrogen doping on the stability and memory window of resistive state switching in N-doped Ta 2 O 5 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 simulations with the screened exchange hybrid functional approximation show 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 the more intermediate states, improving the stability of states, and providing a gradual reset for multi-level cell switching during reset. The N-doped Ta 2 O 5 devices have relatively small set and reset voltages ( < 1 V) with reduced variability due to doping.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:11
Last Modified: 16 Nov 2017 02:09
DOI: