Advanced atomic force microscopy-based techniques for nanoscale characterization of switching devices for emerging neuromorphic applications

Abstract

Neuromorphic systems require integrated structures with high-density memory and selector devices to avoid interference and recognition errors between neighboring memory cells. To improve the performance of a selector device, it is important to understand the characteristics of the switching process. As changes by switching cycle occur at local nanoscale areas, a high-resolution analysis method is needed to investigate this phenomenon. Atomic force microscopy (AFM) is used to analyze the local changes because it offers nanoscale detection with high-resolution capabilities. This review introduces various types of AFM such as conductive AFM (C-AFM), electrostatic force microscopy (EFM), and Kelvin probe force microscopy (KPFM) to study switching behaviors.

Resonant Activation of Resistance Switching in Memristors Based on YSZ Films with Au Nanoparticles

“…Similar results were obtained in the studies of RS in the YSZ films and in the YSZ/Ta 2 O 5 stacks by Conducting Atomic Force Microscopy (CAFM) [11,12]. In these investigations, a contact of the CAFM probe tip to the insulator films (or to the stacks) on the conductive substrates composed a nanometer-scale virtual memristive device [13]. The effect was related to a resonant activation of the electromigration (drift and/or diffusion) of the O 2ions through the V O s due to the alternating electric field [14].…”

Quantum Conductance in Memristive Devices: Fundamentals, Developments, and Applications

“…This availability of signal readouts, combined with a remarkable filament localization capability, comparable to that of TEM and EBIC, has converted SPM methods in some of the most used analytical techniques for failure analysis and reliability studies, involving the use of the nanosized tip as an active electrode for filament formation, or purely as a passive probe. [188,205,206] An interesting novel solution was offered by the concept of tomographic sensing with AFM, often referred to as tomographic-AFM (TAFM) or scalpel SPM. [207][208][209] Here, tip-induced nanoscale abrasive wear in contact-mode AFM, is used for the sub-nanometer material removal obtaining a controlled milling of the surface in combination with the acquisition of the secondary AFM readout (i.e., electrical information).…”

Semiconductor–Semimetal 2D/3D MoS2/SrRuO3(111) TMD/TMO Heterojunction-Based ReRAM Devices

“…However, based on the current image, it can be assumed that the conduction is space charge limited in the case of FL due to charge trapping and detrapping in the MoS 2 thin layer (Figure S4). Further, the log–log plot does indicate ohmic conduction, as shown in Figure C, for the low bias region in both high and low resistance states. Additionally, the MoS 2 /SRO heterojunction can be understood by EFM data, wherein a clear difference in work function (WF) and SBH is observed for the FL and BL MoS 2 at the MoS 2 /SRO heterostructures, respectively …”

“…Therefore, a charge accumulation region should be built in for Φ SM < Φ S at the semimetal−semiconductor junction. 41 One should then expect ohmic I−V characteristics for this SC/SM junction as is reflected in Figure S8.…”