Controlled fabrication of palladium nanoelectrodes for molecular electronics

L. ARZUBIAGA; F. GOLMAR; R. LLOPIS; F. CASANOVA; L. HUESO

Grenoble

Congreso; ElecMol'12 6th International Conference on Molecular Electronics; 2012

Considerable advances have been made in the field of single molecule transistors (SMT) in the last few years [1,2]. However, there are still problems for their systematic fabrication. Two of the principal challenges in single molecule electronics are first, obtaining the adequate electrode geometry and interelectrode distances for forming a SMT and second, achieving a good coupling between electrodes and individual molecules to ensure a good operability of the actual devices [2]. In this work we focus on electromigration, which is a widely used technique for fabricating electrodes of molecular dimensions [3,4]. It consists in opening a breach of a few nanometers in a metallic nanowire by electrical fatigue of the material. A molecule is eventually placed in this breach with the two adjoining nanowire-segments acting as electrodes. Our aim is to improve the ability for controlling the results of the fabrication process, which would eventually lead us to a more reliable fabrication of nanoelectrodes for SMTs. We present a study on electromigration in palladium nanowires. Palladium is a noble metal that becomes ferromagnetic by adding only about 0.1% of Co and it shows intrinsic features in charge-transport [5] that could add new effects to SMTs. This work shows how we control the conditions at which the onset of electromigration occurs in our devices. In addition, we found the appropriate working conditions for obtaining either palladium nanoconstrictions or nanogap electrodes.