Nonlinear flexural response of a suspended Au nanobeam structure undergoing an electromigration-lead breakdown

Seokwon Kang,Seondo Park,Yun Daniel Park

doi:10.1063/5.0020550

Abstract

The nonlinear resonance response of electromechanical structures, such as Duffing resonators, can discern both geometrical and internal anomalies, such as the “softening” response attributed to deviations from an ideal parallel plane for the former and the “hardening” response attributed to internal strains for the latter. Herein, we study the evolution of the nonlinear resonance response of a suspended Au nanobeam structure undergoing a mechanical breakdown due to an electromigration-lead process. Nanogaps are formed by utilizing a feedback-controlled electromigration technique while simultaneously electrostatically driving the free-standing beam. The morphological evolution of the metallic nanobeam structures is further ascertained between feedback iterations by a scanning electron microscopy. We detect a rich nonlinear response when changing from softening to hardening, and vice versa, before the ultimate mechanical breakdown.

Highlights

In the development of nanomachining technology, the miniaturization of electronic devices could progress to less than 5 nm, and future research on devices using molecular electronics may overcome the difficulties of further scaling down in semiconductor technology.1 In order to create molecular electronics or single molecule based devices, nanogap electrodes connected to molecules are needed as probes to measure mechanical,2 optical,3 and thermoelectric properties.4 Of the many creative technologies to realize nanogaps, such as mechanically controlled breakjunctions (MCBJs),5 electromigration breakjunctions (EBJs),6 and scanning probe microscopy (SPM) techniques,7 the EBJ method has received much attention despite its well-known disadvantages, difficulties in achieving reliable and repeatable control of the nanogap sizes
Much progress has been made in researching the EM breakdown junction mechanism and observing the nanogap formation process using a scanning electron microscope (SEM), transmission electron microscope (TEM), and atomic force microscope (AFM)
In order to avoid thermal runaway due to excessive heating in the metallic nanostructures, the feedback-controlled electromigration (FCE) process is utilized in this experiment

Summary

Introduction

In the development of nanomachining technology, the miniaturization of electronic devices could progress to less than 5 nm, and future research on devices using molecular electronics may overcome the difficulties of further scaling down in semiconductor technology.1 In order to create molecular electronics or single molecule based devices, nanogap electrodes connected to molecules are needed as probes to measure mechanical,2 optical,3 and thermoelectric properties.4 Of the many creative technologies to realize nanogaps, such as mechanically controlled breakjunctions (MCBJs),5 electromigration breakjunctions (EBJs),6 and scanning probe microscopy (SPM) techniques,7 the EBJ method has received much attention despite its well-known disadvantages, difficulties in achieving reliable and repeatable control of the nanogap sizes. We investigate the evolution of the nonlinear resonance response of a suspended Au nanobeam structure undergoing an EM-lead breakdown to discern geometrical and internal anomalies.

Results

Conclusion