Direct resistance profile for an electrical pulse induced resistance change device

Abstract

We report the first direct measurements of the micro scale resistance profile between the terminals of a two terminal symmetric thin film Pr0.7Ca0.3MnO3 electrical pulse induced resistance change device composed of a Pr0.7Ca0.3MnO3 active layer. The symmetric device is one in which the electrode shape, size, composition, and deposition processing are identical. We show that under certain limitations of pulse switching voltage, such a symmetric electrical pulse induced resistance change device can exhibit either no net device resistance switching at room temperature, or bipolar switching with the resistance hysteresis curve exhibiting a "table leg" structure. The resistance measurements are made using surface scanning Kelvin probe microscopy, which allows for the measurement of the profile of resistance from one electrode, across the Pr0.7Ca0.3MnO3 material and into the second electrode, both before resistance switching and after switching. The results show that resistance switching in the symmetric device occurs primarily in the interface region within about 1 to 3 micron of the electrical contact surface. Resistance switching is also observed in the bulk Pr0.7Ca0.3MnO3 material although at a lower level. Symmetry considerations for a two terminal symmetric device that can switch resistance are discussed, and the data reported here is consistent with the symmetric model previously developed.[*]

Shock Waves and Commutation Speed of Memristors

“…The drift current is generally given by the expression j drift ¼ ugðEÞ. The form of the function gðEÞ is material dependent, and here we envision two limiting situations.In homogeneous conductors, we should have simple "Ohmic" behavior as gðEÞ ∼ E, while in granular materials, we expect exponential dependence due to activated transport, corresponding to gðEÞ ∼ sinh ðE=E 0 Þ, where E 0 is a parameter describing the activation process.Remarkably, these general ideas find an explicit realization in the context of RS in transition metal oxide memristors, such as manganites [15,32]. In fact, their transport properties are very sensitively dependent on the oxygen stoichiometry, i.e., on the concentration of oxygen…”

“…Remarkably, these general ideas find an explicit realization in the context of RS in transition metal oxide memristors, such as manganites [15,32]. In fact, their transport properties are very sensitively dependent on the oxygen stoichiometry, i.e., on the concentration of oxygen…”

“…In particular, the important role of highly resistive interfaces, such as Schottky barriers (SBs), has also been pointed out [7,9,15].…”

“…with α ¼ SB, B, where SB denotes the highly resistive (Schottky-barrier) region and B the more conductive bulk [15]. The values of these constants are taken as A SB ≫ A B ¼ 1, which allows us to neglect the bulk resistance [27].…”

“…Within the framework of this model, we perform numerical simulations to validate our shock-wave scenario. The VEOVM simply assumes that the local resistance of the cell at (discretized) position x along the conductive path of the device is simply given as a linear function of the local vacancy concentration, namely,with α ¼ SB, B, where SB denotes the highly resistive (Schottky-barrier) region and B the more conductive bulk [15]. The values of these constants are taken as A SB ≫ A B ¼ 1, which allows us to neglect the bulk resistance [27].…”