Resistive Switching in Nanodevices

TL;DR

This paper explains resistive switching in nanoscale metal/insulator/metal devices as a result of different spontaneous charge states caused by band bending, revealing the physical mechanism behind resistive state changes.

Contribution

It introduces a physical model based on band bending solutions of Poisson's equation to explain resistive switching, and proposes a new magnetic memristor device with enhanced storage capacity.

Findings

Resistive states correspond to different charge distributions due to band bending.

Switching occurs only at nanoscale and specific bias voltages.

A new magnetic memristor device with increased storage capacity is proposed.

Abstract

Passing current at given threshold voltages through a metal/insulator/metal sandwich structure device may change its resistive state. Such resistive switching is unique to nanoscale devices, but its underlying physical mechanism remains unknown. We show that the different resistive states are due to different spontaneously charged states, characterized by different `band bending' solutions of Poisson's equation. For an insulator with mainly donor type defects, the low-resistivity state is characterized by a negatively charged insulator due to convex band bending, and the high-resistivity state by a positively charged insulator due to concave band bending; vice versa for insulators with mainly acceptor type defects. These multiple solutions coexist only for nanoscale devices and for bias voltages limited by the switching threshold values, where the system charge spontaneously changes and the system switches to another resistive state. We outline the general principles how this functionality depends on material properties and defect abundance of the insulator `storage medium', and propose a new magnetic memristor device with increased storage capacity.