Dependence of Electric Properties of a Nanogap Junction on Electrode Material

Abstract

Oblique deposition was used to fabricate two metal electrodes separated by a gap of less than 10 nm on a SiO2 substrate. By sweeping voltage between these electrodes, a negative resistance change of several digits was observed in vacuum. In this work, electrodes made of Au, Pd, Pt, and Ta were fabricated, and their electric properties were measured in vacuum. The negative resistance was observed for all of the four metals. The result of the measurements clearly shows the correlation between the voltage at the minimum resistance and the melting point. Also, the calculated temperature rise shows a correlation with the melting point. These facts support the effect that the thermal change of the electrode metal has a considerable effect on the electric properties of the nanogap switch (NGS).

Resistive switching effects in single metallic tunneling junction with nanometer-scale gap

“…The resistive switching occurs on Pd, Pt, and Ta electrodes as well as Au electrodes. 8 Furthermore, it is also observed in the NGJs made of silicon electrodes, which demonstrates that the NGJ is compatible with semiconductor process. 9 Therefore, the NGJ is expected as a building block of the next-generation memory systems.…”

“…5 For the realization of ultrahigh density memory devices, the structure of the individual memory cell should be as simple as possible. Recently, Naitoh and co-workers [6][7][8][9][10] reported a negative differential resistance ͑NDR͒ characteristics in metallic electrode junctions with a nanometer-scale gap. They also found that the current-voltage ͑I-V͒ curves of those nanoscale-gap junctions ͑NGJs͒ exhibit nonvolatile resistance switching phenomena even though the NGJs do not have any memristive medium between electrodes.…”

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

“…The differences in the HRS and LRS were then supposed to be due to tunneling current at different scales. To this end there is significant evidence that the reported nanogap switching behaviour is due to tunnelling current and a change in gap size, namely the temperature independence of the current, multilevel switching, [53] dependence of switching on the electrode material, [41] and independence of the switching behaviour on substrate material [54]. However, there is also significant evidence that switching can be due to a breakdown in the dielectric substrate (often SiO2), such as an independence of switching on electrode material [33], evidence of damage to the substrate [55], and direct imaging of filamentation taking place [28].…”

Non-volatile high-speed resistance switching nanogap junction memory

“…Further, the memory has a wide selectivity of metals such as Pt, Ta, W, and Si and other nanostructures. 13,14 Earlier, we demonstrated a multilevel resistance switching and the possibility of increasing the bit capacity per cell. 15 Therefore, the nanogap switch based memory is scalable to ultrahigh densities.…”