A "grow-in-place" architecture and methodology for electrochemical synthesis of conducting polymer nanoribbon device arrays

Fully enclosed horizontal nanochannels, in a prearranged array on a substrate and with built-in electrical contacts and chemical access regions, were used as growth templates for electrochemical synthesis of conducting polymer nanoribbons. In this "grow-in-place" approach, the nanochannel templates are part of the final array structure and remain after fabrication of the nanoribbons. The built-in electrical contacts, which provide the electrical potential for electrochemical polymerization, also remain and become contacts/interconnects to the array components. The grow-in-place architecture and methodology remove the need for template dissolution, any post-synthesis nanoribbon "grow-and-then-place" manipulation, and any post-synthesis electrical contacting. The fact that the templates are fully enclosed prohibits dendrite formation during growth, ensures precise dimensionality, and gives the encapsulation needed in any real device application. In this report the grow-in-place approach to electrochemical polymerization is used to produce polyaniline nanoribbons. These were found to be fibrils and not tubes and to grow from the central region of the growth-template cross-section and not from the template walls. Two-point and four-point electrical characterization of these polyaniline nanoribbons, obtained using the built-in electrodes, was employed to yield the true polyaniline conductivity and to assess the ohmicity of the contacting approach. Conductivity studies, done as a function of nanoribbon width, show conductivity increases as the width decreases. We also show that our grow-in-place approach may be used for chemical polymerization. However, at least for polyaniline, electrochemical polymerization is superior since it does not suffer from diffusion-limited growth and allows precise placement of the nanoribbons in the growth channel.