Assembly and electrical characterization of DNA-wrapped carbon nanotube devices

Abstract

In this article we report on the electrical characteristics of single wall carbon nanotubes (SWCNTs) wrapped with single-stranded deoxyribonucleic acid (ssDNA). We fabricate these devices using a solution-based method whereby SWCNTs are dispersed in aqueous solution using 20-mer ssDNA, and are placed across pairs of Au electrodes using alternating current dielectrophoresis (ACDEP). In addition to current voltage characteristics, we evaluate our devices using scanning electron microscopy and atomic force microscopy. We find that ACDEP with ssDNA based suspensions results in individual SWCNTs bridging metal electrodes, free of carbon debris, while similar devices prepared using the Triton X-100 surfactant yield nanotube bundles, and frequently have carbon debris attached to the nanotubes. Furthermore, the presence of ssDNA around the nanotubes does not appear to appreciably affect the overall electrical characteristics of the devices. In addition to comparing the properties of several devices prepared on nominally clean Au electrodes, we also investigate the effects of self-assembled monolayers of C 14 H 29 -SH alkyl thiol and benzyl mercaptan on the adhesion and electrical transport across the metal/SWCNT/metal devices.

A Substrate‐Independent Approach for the Surface Immobilization of Oligonucleotides using Aldehyde Functionalized Surfaces

“…For instance, CNTs are of interest due to their unique physical and chemical properties (including exceptional mechanical properties, [48] and electrical [49] and thermal conductivity [50] ). The introduction of ssDNA onto SWNTs can enhance CNT dispersion in aqueous media for nanodevice fabrication, [51] and presents new exciting opportunities for the precise patterning of CNT layers, whilst DNA-functionalized polymer microbeads are of great interest in the field of combinatorial chemistry.…”

Effect of electrode material on transport and chemical sensing characteristics of metal/carbon nanotube contacts

“…The presence of ssDNA around the nanotube, compared to other surfactants, does not appreciably affect the overall electrical characteristics of the devices. 4 However, the resistance is higher than for ballistic conductance for metallic SWCNTs. [5][6][7] While the origin of this higher resistance is speculated to be contact resistance between the nanotube and the electrode contact, we aim to develop a deeper understanding of this.…”

“…10 The main advantage of this technique is that one can easily vary the electrode material and introduce surface coatings, such as a selfassembled monolayer of an alkylthiol on Au. 4 We characterize the surface chemical composition of our Pd and Pd/PdO electrodes, determine the PdO thickness, and measure the electrical transport across Pd/SWCNT and Pd/PdO/SWCNT junctions. SWCNTs placed directly on clean Pd electrodes indeed form Ohmic contacts, albeit having high resistance, while transport across oxidized Pd electrodes is completely determined by tunneling.…”

RF/Microwave properties and applications of directly assembled nanotubes and nanowires: LDRD project 102662 final report.

“…1 insets). A previous study [18] of SWCNT transistors fabricated using very similar ACDEP conditions showed that roughly 1/5 of the devices exhibited semiconducting characteristics, with the rest metallic. No post-deposition annealing was done.…”

“…These nanomaterials were separated and put into suspension, and then directly assembled onto broadband co-planar waveguides (CPWs) using AC dielectrophoresis (ACDEP), [17,18] as illustrated in the insets of Fig. 1.…”