Nanotechnology

Switching kinetics of a Cu₂S-based gap-type atomic switch

Alpana Nayak¹, Tohru Tsuruoka¹, Kazuya Terabe¹, Tsuyoshi Hasegawa¹ and Masakazu Aono¹

Published 11 April 2011 • IOP Publishing Ltd
Nanotechnology, Volume 22, Number 23 Citation Alpana Nayak et al 2011 Nanotechnology 22 235201

Abstract

The switching time of a Cu₂S-based gap-type atomic switch is investigated as a function of temperature, bias voltage, and initial off-resistance. The gap-type atomic switch is realized using a scanning tunneling microscope (STM), in which the formation and annihilation of a Cu-atom bridge in the vacuum gap between the Cu₂S electrode and the Pt tip of the STM are controlled by a solid-electrochemical reaction. Increasing the temperature decreases the switching time exponentially with an activation energy of about 1.38 eV. Increasing the bias voltage also shortens the switching time exponentially, exhibiting a greater exponent for the lower bias than for the higher bias. Furthermore, faster switching has been achieved by decreasing the initial off-resistance between the Cu₂S electrode and STM tip. On the basis of these results, we suggest that, in addition to the chemical reaction, the electric field in the vacuum gap plays a significant role in the operation of a gap-type atomic switch. This investigation advances our understanding of the operating mechanism of an atomic switch, which is a new concept for future electronic devices.

The post Switching kinetics of a Cu2S-based gap-type atomic switch appeared first on Nanoarchitectonics Lab.

Alpana Nayak ¹, Qi Wang, Yaomi Itoh, Tohru Tsuruoka, Tsuyoshi Hasegawa, Liam Boodhoo, Hiroshi Mizuta, Masakazu Aono

Affiliation

• ¹WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo, 102-0075, Japan.

• PMID: 25772614
• DOI: 10.1088/0957-4484/26/14/145702

Abstract

Resistive random access memories (ReRAMs) are promising next-generation memory devices. Observation of the conductive filaments formed in ReRAMs is essential in understanding their operating mechanisms and their expected ultimate performance. Finding the position of the conductive filament is the key process in the preparation of samples for cross-sectional transmission electron microscopy (TEM) imaging. Here, we propose a method for locating the position of conductive filaments hidden under top electrodes. Atomic force microscopy imaging with a conductive tip detects the current flowing through a conductive filament from the bottom electrode, which reaches its maximum at a position that is above the conductive filament. This is achieved by properly biasing a top electrode, a bottom electrode and the conductive tip. This technique was applied to Cu/Ta2O5/Pt atomic switches, revealing the formation of a single Cu filament in a device, although the device had a large area of 5 × 5 μm(2). Change in filament size was clearly observed depending on the compliance current used in the set process. It was also found from the TEM observation that the cross-sectional shape of the formed filament varies considerably, which is attributable to different Cu nuclei growth mechanisms.

The post Position detection and observation of a conducting filament hidden under a top electrode in a Ta₂O₅-based atomic switch appeared first on Nanoarchitectonics Lab.