Controlling Cu Migration on Resistive Switching, Artificial Synapse, and Glucose/Saliva Detection by Using an Optimized AlO_x Interfacial Layer in a-CO_x-Based Conductive Bridge Random Access Memory

Abstract

The Cu migration is controlled by using an optimized AlO x interfacial layer, and effects on resistive switching performance, artificial synapse, and human saliva detection in an amorphous-oxygenated-carbon (a-CO x )-based CBRAM platform have been investigated for the first time. The 4 nm-thick AlO x layer in the Cu/AlO x /a-CO x /TiN x O y /TiN structure shows consecutive >2000 DC switching, tight distribution of SET/RESET voltages, a long program/erase (P/E) endurance of >109 cycles at a low operation current of 300 μA, and artificial synaptic characteristics under a small pulse width of 100 ns. After a P/E endurance of >108 cycles, the Cu migration is observed by both ex situ high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy mapping images. Furthermore, the optimized Cu/AlO x /a-CO x /TiN x O y /TiN CBRAM detects glucose with a low concentration of 1 pM, and real-time measurement of human saliva with a small sample volume of 1 μL is also detected repeatedly in vitro. This is owing to oxidation–reduction of Cu electrode, and the switching mechanism is explored. Therefore, this CBRAM device is beneficial for future artificial intelligence application.

Contact Engineering Approach to Improve the Linearity of Multilevel Memristive Devices

“…The high energy gap of Al 2 O 3 ensures the maintenance of the high R OFF /R ON ratio, whereas its high thermal conductivity (15 W/mK) facilitates the formation of Cu ion conductive filament [35]. In addition, oxidation of Cu electrode at the Al 2 O 3 /Cu-TE interface provides a higher migration rate of Cu 2+ ions due to the lower Cu-O bond energy compared with that of Cu-Cu metallic bond (1.5 eV vs. 2.0 eV [36]).…”

Au and Pt Diffusion in Electrodeposited Amorphous Sb2Te3 Thin Films

“…This is probably due to the covalent nature of Te atoms, which are not as mobile as the metal species, and the fact that the electrodeposited Sb 2 Te 3 films are uniform in chemical composition along the depth of the film and thus there is no concentration gradient to promote the diffusion. Another interesting feature of this work is that in general, Ag and Cu have been commonly used as active electrodes in CBRAM devices [13,14] ; however, our accidental discovery of the diffusive nature of some noble metals such as Au and Pt in a chalcogenide solid electrolyte (i.e., amorphous Sb 2 Te 3 ) could open a new area in chalcogenide-based CBRAM devices.…”

Organismic Memristive Structures With Variable Functionality for Neuroelectronics

“…In this case, copper is considered as a volatile (mobile) dopant. The oxidation of the Cu electrode at the Al 2 O 3 /Cu–TE interface provides a higher migration rate of Cu ions due to the lower Cu–O bond energy compared to that of the Cu–Cu metallic bond (1.5 vs. 2.0 eV) ( Ginnaram et al, 2020 ).…”