Electric field breakdown in single molecule junctions.

Abstract

Here we study the stability and rupture of molecular junctions under high voltage bias at the single molecule/single bond level using the scanning tunneling microscope-based break-junction technique. We synthesize carbon-, silicon-, and germanium-based molecular wires terminated by aurophilic linker groups and study how the molecular backbone and linker group affect the probability of voltage-induced junction rupture. First, we find that junctions formed with covalent S-Au bonds are robust under high voltage and their rupture does not demonstrate bias dependence within our bias range. In contrast, junctions formed through donor-acceptor bonds rupture more frequently, and their rupture probability demonstrates a strong bias dependence. Moreover, we find that the junction rupture probability increases significantly above ∼1 V in junctions formed from methylthiol-terminated disilanes and digermanes, indicating a voltage-induced rupture of individual Si-Si and Ge-Ge bonds. Finally, we compare the rupture probabilities of the thiol-terminated silane derivatives containing Si-Si, Si-C, and Si-O bonds and find that Si-C backbones have higher probabilities of sustaining the highest voltage. These results establish a new method for studying electric field breakdown phenomena at the single molecule level.

• Authors: Haixing Li, Timothy A Su, Vivian Zhang, Michael L Steigerwald, Colin Nuckolls, Latha Venkataraman
• Journal: Journal of the American Chemical Society (J Am Chem Soc) Vol. 137 Issue 15 Pg. 5028-33 (Apr 22 2015) ISSN: 1520-5126 [Electronic] United States
• PMID: 25675085 (Publication Type: Journal Article)