Insights into Nanoscale Electrochemical Reduction in a Memristive Oxide: the Role of Three‐Phase Boundaries

Abstract

The nanoscale electro-reduction in a memristive oxide is a highly relevant fi eld for future non-volatile memory materials. Photoemission electron microscopy is used to identify the conducting fi laments and correlate them to structural features of the top electrode that indicate a critical role of the three phase boundary (electrode-oxide-ambient) for the electro-chemical reduction. Based on simulated temperature profi les, the essential role of Joule heating through localized currents for electro-reduction and morphology changes is demonstrated.

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO3 Thin Film Devices

“…[ 17 ] In particular, during the initial electroforming step, the temperatures may come close to the melting temperature of the oxide. [ 18 ] Under these severe conditions it is expected that also cationic defects are generated and moved in SrTiO 3 despite of their high formation and migration energies.…”

“…[18][19][20] In general, the segregation of A-site cations during deposition, temperature treatment or oxidation/reduction of complex transition metal oxides is well known. [21][22][23][24][25] Regarding the impact of cationic defects and their movement during the electroforming and resistive switching of SrTiO 3 , it is not yet known how such defects are generated, whether their movement or generation is reversible, and whether they are incorporated into the lattice or precipitated as secondary phases.…”

Band alignment at memristive metal-oxide interfaces investigated by hard x-ray photoemission spectroscopy

“…However, intentional acceptor doping reduces the amount of free charge carriers by trapping the free carriers induced through V [29,30]. We therefore deal with n-doped films even when admixing substantial amounts of acceptor-type cations.…”

Functional materials for information and energy technology: Insights by photoelectron spectroscopy

“…With a lateral resolution of a few 10 nm, energyfiltered photoemission microscopes are ideally suited to tackle this challenge. Studies in the soft x-ray regime have already contributed significantly to the understanding of the microscopic processes during electroforming in Fe-doped SrTiO 3 [40] and resistive switching in GaO x [41]. h!…”