title: 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: †Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors: Haixing
authors: H
authors: Li
authors: †Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors: Timothy A
authors: TA
authors: Su
authors: †Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors: Vivian
authors: V
authors: Zhang
authors: †Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors: Michael L
authors: ML
authors: Steigerwald
authors: †Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors: Colin
authors: C
authors: Nuckolls
authors: †Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors: Latha
authors: L
authors: Venkataraman