Reversible Bistable Switching in Nanoscale Thiol-Substituted Oligoaniline Molecular Junctions

• Published in: Nano letters 2005-12, Vol.5 (12), p.2365-2372
• Main Authors: Cai, Lintao, Cabassi, Marco A, Yoon, Heayoung, Cabarcos, Orlando M, McGuiness, Christine L, Flatt, Austen K, Allara, David L, Tour, James M, Mayer, Theresa S
• Format: Article
• Language: English
• Subjects: Aniline Compounds - chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electric Conductivity; Electrochemistry - instrumentation; Electrochemistry - methods; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in interface structures; Electronics; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Materials science; Materials Testing; Nanoscale materials and structures: fabrication and characterization; Nanotechnology - instrumentation; Nanotechnology - methods; Nanotubes - chemistry; Nanotubes - ultrastructure; Physics; Quantum wires; Semiconductors; Signal Processing, Computer-Assisted - instrumentation; Sulfhydryl Compounds - chemistry; Tunneling
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl051219k

Single molecular monolayers of oligoaniline dimers were integrated into sub-40-nm-diameter metal nanowires to form in-wire molecular junctions. These junctions exhibited reproducible room temperature bistable switching with zero-bias high- to low-current state conductance ratios of up to 50, switching threshold voltages of approximately ±1.5 V, and no measurable decay in the high-state current over 22 h. Such switching was not observed in similarly fabricated saturated dodecane (C12) or conjugated oligo(phenylene ethynylene) (OPE) molecular junctions. The low- and high-state current versus voltage was independent of temperature (10−300 K), suggesting that the dominant transport mechanism in these junctions is coherent tunneling. Inelastic electron tunneling spectra collected at 10 K show a change in the vibrational modes of the oligoaniline dimers when the junctions are switched from the low- to the high-current state. The results of these measurements suggest that the switching behavior is an inherent molecular feature that can be attributed to the oligoaniline dimer molecules that form the junction.