Observing "Quantized" Conductance Steps in Silver Sulfide: Two Parallel Resistive Switching Mechanisms

TL;DR

This study distinguishes two conductance switching mechanisms in silver sulfide devices at room temperature, revealing quantized conductance steps and the formation of metallic silver nanowires through experimental STM measurements.

Contribution

It demonstrates the ability to differentiate between metallic nanowire formation and lattice deformation as two resistive switching mechanisms in Ag$_2$S thin films.

Findings

Observation of quantized conductance steps during nanowire breaking.

Identification of a high conductance state related to metallic silver filament formation.

Evidence of lattice deformation through gradual conductance changes.

Abstract

We demonstrate that it is possible to distinguish two conductance switching mechanisms in silver sulfide devices at room temperature. Experiments were performed using a Ag$_2$S thin film deposited on a wide Ag bottom electrode, which was contacted by the Pt tip of a scanning tunneling microscope. By applying a positive voltage on the silver electrode the conductance is seen to switch to a state having three orders of magnitude higher conductance, which is related to the formation of a conductive path inside the Ag$_2$S thin film. We argue this to be composed of a metallic silver nanowire accompanied by a modification of the surrounding lattice structure. Metallic silver nanowires decaying after applying a negative voltage allow observing conductance steps in the breaking traces characteristic for atomic-scale contacts, while the lattice structure deformation is revealed by gradual and continuously decreasing conductance traces.