Quantifying redox-induced Schottky barrier variations in memristive devices via in operando spectromicroscopy with graphene electrodes

Abstract

The continuing revolutionary success of mobile computing and smart devices calls for the development of novel, cost- and energy-efficient memories. Resistive switching is attractive because of, inter alia, increased switching speed and device density. On electrical stimulus, complex nanoscale redox processes are suspected to induce a resistance change in memristive devices. Quantitative information about these processes, which has been experimentally inaccessible so far, is essential for further advances. Here we use in operando spectromicroscopy to verify that redox reactions drive the resistance change. A remarkable agreement between experimental quantification of the redox state and device simulation reveals that changes in donor concentration by a factor of 2–3 at electrode-oxide interfaces cause a modulation of the effective Schottky barrier and lead to >2 orders of magnitude change in device resistance. These findings allow realistic device simulations, opening a route to less empirical and more predictive design of future memory cells.

Influence of Dislocations in Transition Metal Oxides on Selected Physical and Chemical Properties

“…In fact, thermodynamic arguments show [268] that if the resistive switching would only be induced by a change of the center of gravity of the population of point defects in the crystal the induced, new resistance state would not be stable on a long time scale. We therefore argue that the chemical and crystallographic transformation of the core of dislocations seems to be a plausible alternative to models which solely rely on a Schottky-type disorder [267,269,270]. …”

The influence of non-stoichiometry on the switching kinetics of strontium-titanate ReRAM devices

“…10,[13][14][15][16][17] Current studies are discussing the possibility of oxygen transfer reactions between the oxide and the metal electrodes as additional effects involved in VCM-type resistive switching. [18][19][20] Due to its thoroughly investigated defect chemistry, strontium titanate (STO) is often used as a model system for resistive switching. 21,22 Recently, several studies have dealt with the influence of stoichiometry on resistive switching in STO, revealing differences in forming voltage and statistics, 23 data retention, 24 or even switching/no-switching.…”

Oxygen migration during resistance switching and failure of hafnium oxide memristors

“…[1][2][3][4][5] There has been particular interest in understanding the role of migration of oxygen atoms in determining the operation of memristors. [6][7][8][9][10][11] Similar recent advances in understanding the localized nanoscale physico-chemical changes underlying resistance switching 4,[12][13][14][15] have opened up fresh interests into studying the effect of atomic movements on extended device operation and the nanoscale material behavior during eventual failure and possible techniques to mitigate such failure. [16][17][18] To enable scanning transmission x-ray microscopy (STXM) measurements, each device was built on a 200 nm low-stress Si 3 N 4 film suspended over 50 µm x 50 µm holes etched through a silicon substrate.…”