Development And Application Of Automatic Electromigration Testing Platform Based On Mechanical Controllable Break Junction

With the size of traditional silicon-based circuit devices approaching the physical limit,organic molecular devices,as one of the important alternatives,have attracted more and more attention.To connect a single molecule in the loop,many kinds of methods for creating electrode pairs with nanoscale gap lengths have been tried.As a simple process with strong versatility,high interoperability and large-scale preparation potential,electromigration breakdown junction is worth studying and has good prospects in application.In recent years,researchers used electromigration technology to fabricate electrode pairs and measure the electrical transport properties of the single molecule,but there still remains some urgent problems in related fields.On the one hand,the research about the operating conditions and control scheme of electromigration is still not deep enough,and the success rate of creating electrode pairs with crack distance in 2 nm or less needs to be improved.On the other hand,due to the complexity of the microscopic mechanism of electromigration,the understanding of its variation characteristics is not complete,and the influence of conductor material structure and external environment on the process of electromigration still needs to be further explored.Therefore,in this thesis,we combined the mechanical controllable break junctions technology with electromigration technology,and developed instrument for automatic electromigration test and fracture distance measurement.Based on this,the effects on common control strategies for the process of fabricating electrode pairs with nanogaps by electromigration are tested and analyzed.The main research contents and results of this thesis are as follows:1.An automatic test platform for the fabrication of electrode pairs with nanogaps by electromigration has been built.It has a sampling frequency of 10 kHz,together with wide range and high precision current measuring range of mA-pA level.At the same time,by utilizing motion system formed by precision stepping motor and piezoelectric actuator,the instrument can measure the gap distance of the fabricated electrode pair accurately,combining with the unique motion attenuation feature of MCBJ.In addition,this instrument is also compatible for electromigration and further single-molecule devices fabrication and characterization on micro/nano-fabricated samples.2.The online control program and offline data analysis program are developed for the electromigration test platform.The online program can control the equipment to finish the operation steps including stretching hovering,migration cracking and gap distance measurement.On this basis,the automatic cycle experiment can be realized,and the experimental data can be recorded.The offline analysis program can help users to complete the statistical analysis and visualization of electromigration experimental data.3.Using this self-built test platform,the control scheme of nano-gap electrodes pair prepared by electromigration was studied.The performance of common migration control schemes is tested and analyzed,and new methods such as target-guided PID control strategy are developed,which provides a reference for related research.Finally,the electromigration and molecular device fabrication experiments were carried out on micro/nano-fabrication samples,which verified the effectiveness of the control strategy in the real application environment.