Local Ion
Irradiation-Induced Resistive Threshold
and Memory Switching in Nb<sub>2</sub>O<sub>5</sub>/NbO<sub><i>x</i></sub> Films
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Abstract
Resistive switching devices with a Nb<sub>2</sub>O<sub>5</sub>/NbO<sub><i>x</i></sub> bilayer stack combine threshold and memory
switching. Here we present a new fabrication method to form such devices.
Amorphous Nb<sub>2</sub>O<sub>5</sub> layers were treated by a krypton
irradiation. Two effects are found to turn the oxide partly into a
metallic NbO<sub><i>x</i></sub> layer: preferential sputtering
and interface mixing. Both effects take place at different locations
in the material stack of the device; preferential sputtering affects
the surface, while interface mixing appears at the bottom electrode.
To separate both effects, devices were irradiated at different energies
(4, 10, and 35 keV). Structural changes caused by ion irradiation
are studied in detail. After successful electroforming, the devices
exhibit the desired threshold switching. In addition, the choice of
the current compliance defines whether a memory effect adds to the
device. Findings from electrical characterization disclose a model
of the layer modification during irradiation