Current localisation and redistribution as the basis of discontinuous current controlled negative differential resistance in NbOx

Sanjoy Kumar Nandi; Shimul Kanti Nath; Assaad El Helou; Shuai Li; Xinjun Liu; Peter E. Raad; Robert G. Elliman

doi:10.1002/adfm.201906731

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arXiv · 1906.08980

Current localisation and redistribution as the basis of discontinuous current controlled negative differential resistance in NbOx

Sanjoy Kumar Nandi·Shimul Kanti Nath·Assaad El Helou·Shuai Li·Xinjun Liu·Peter E. Raad·Robert G. Elliman

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Abstract

In-situ thermo-reflectance imaging is used to show that the discontinuous, snap-back mode of current-controlled negative differential resistance (CC-NDR) in NbOx-based devices is a direct consequence of current localization and redistribution. Current localisation is shown to result from the creation of a conductive filament either during electroforming or from current bifurcation due to the super-linear temperature dependence of the film conductivity. The snap-back response then arises from current redistribution between regions of low and high current-density due to the rapid increase in conductivity created within the high current density region. This redistribution is further shown to depend on the relative resistance of the low current-density region with the characteristics of NbOx cross-point devices transitioning between continuous and discontinuous snap-back modes at critical values of film conductivity, area, thickness and temperature, as predicted. These results clearly demonstrate that snap-back is a generic response that arises from current localization and redistribution within the oxide film rather than a material-specific phase transition, thus resolving a long-standing controversy.

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Sanjoy Kumar Nandi, Shimul Kanti Nath, Assaad El Helou, Shuai Li, Xinjun Liu, Peter E. Raad, Robert G. Elliman. 2019-06-21. Current localisation and redistribution as the basis of discontinuous current controlled negative differential resistance in NbOx. https://doi.org/10.1002/adfm.201906731

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