Highly stable, extremely high-temperature, nonvolatile memory based on resistance switching in polycrystalline Pt nanogaps

Abstract

Highly stable, nonvolatile, high-temperature memory based on resistance switching was realized using a polycrystalline platinum (Pt) nanogap. The operating temperature of the memory can be drastically increased by the presence of a sharp-edged Pt crystal facet in the nanogap. A short distance between the facet edges maintains the nanogap shape at high temperature, and the sharp shape of the nanogap densifies the electric field to maintain a stable current flow due to field migration. Even at 873 K, which is a significantly higher temperature than feasible for conventional semiconductor memory, the nonvolatility of the proposed memory allows stable ON and OFF currents, with fluctuations of less than or equal to 10%, to be maintained for longer than eight hours. An advantage of this nanogap scheme for high-temperature memory is its secure operation achieved through the assembly and disassembly of a Pt needle in a high electric field.

Electromigration and the structure of metallic nanocontacts

“…To form a controllable switch, it should in addition be possible to reverse the process. Such reversibles processes have been demonstrated (Naitoh et al, 2006;Strachan et al, 2008;Schirm et al, 2013;Lim et al, 2013;and Suga et al, 2016).…”

“…Cyclic electromigration behavior at the atomic scale has been observed (Schirm et al, 2013). It has been proposed that new memory devices could be built on the basis of atomic switches Hasegawa, 2010 andSuga et al, 2016) and first systems are being commercialized (Kaeriyama et al, 2005).…”

Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography

“…The concept of using empty nanogap electrodes as switching devices is potentially far more interesting than conventional structures, owing to the simplicity of the system from a fabrication point of view (no insulator/semiconductor material is required) and the possibility of increasing device density. The cause of switching is still debated, being attributed to either conductive filaments forming through the substrate [28], [30]- [33] or changes in the nanogap dimensions leading to different values of tunnel current [34]- [45] . The apparent bottleneck to the broad adoption of this type of approach however is the difficulty of the fabrication of nanogap electrodes at high throughput and low cost.…”

Thermal robustness evaluation of nonvolatile memory using Pt nanogaps

“…1(a), the reconstruction of the Pt grains also occurred as in previous studies. 6,18) Such a faceted nanogap has the advantage of suppressing the facile migration of Pt atoms during resistance switching. Side wall structures of the etched SiO 2 layer, the height of which was about 50 nm, are clearly shown.…”

“…[3][4][5] In a previous study, we realized the first extremely high-temperature heat-resistant memory based on a polycrystalline Pt nanogap. 6) During operation, this memory exhibits a clear on=off ratio even at 873 K. When this is used over a wide temperature range, the resistance states at different temperatures can be misidentified when the resistance is strongly dependent on temperature. Since memory devices such as dynamic random access memory (DRAM) and flash memory generally have semiconductor channels, the conduction mechanism also involves carrier conduction in silicon channels, and temperature dependences are reflected by thermal activations.…”