Random barrier double-well model for resistive switching in tunnel barriers

TL;DR

This paper introduces a double-well trap model to explain resistive switching in MgO tunnel junctions, demonstrating power-law behaviors in resistance and hysteresis that align with experimental data and vary with temperature.

Contribution

The paper presents a novel double-well trap model for charged defects in MgO, capturing the power-law dynamics of resistive switching and hysteresis observed experimentally.

Findings

Power-law dependence of resistance on time under bias

Power-law relation of hysteresis with voltage sweep frequency

Exponent of power laws varies with temperature as predicted

Abstract

The resistive switching phenomenon in MgO-based tunnel junctions is attributed to the effect of charged defects inside the barrier. The presence of electron traps in the MgO barrier, that can be filled and emptied, locally modifies the conductance of the barrier and leads to the resistive switching effects. A double-well model for trapped electrons in MgO is introduced to theoretically describe this phenomenon. Including the statistical distribution of potential barrier heights for these traps leads to a power-law dependence of the resistance as a function of time, under a constant bias voltage. This model also predicts a power-law relation of the hysteresis as a function of the voltage sweep frequency. Experimental transport results strongly support this model and in particular confirm the expected power laws dependencies of resistance. They moreover indicate that the exponent of these power laws varies with temperature as theoretically predicted.