The NQPI Seminar Series presents John Harb of Brigham Young University, on Thursday, Oct. 24, at 4:10 p.m. in Clippinger Labs 194.
John Harb
Abstract: Bottom-up nanofabrication utilizing self-assembled DNA templates has the potential to create circuits and devices with complex geometries and functionality. In this presentation, we describe our efforts to fabricate nanowires, including the design and assembly of DNA origami templates, seeding of templates with nanorods, electroplating to make continuous nanowires, electrical testing of the wires, methods to improve production yields, and site-specific placement to form wires with metal-semiconductor junctions. Rods were formed with use of a CTAB surfactant, coated with DNA, and then molecularly directed to specific locations on either wireframe or tile templates. The seeding process was critical to successful nanowire fabrication. A method was developed for anisotropic electroless deposition to fill in gaps between nanorods and found to enable the fabrication of continuous high-aspect-ratio wires. Several different self-assembled Au nanowire arrangements on 70 nm × 90 nm DNA origami tiles have been demonstrated. The factors that limit the yields of these nanostructures have been identified and methods for yield improvement have increased yields as much as 6-fold. Unprecedented four-point conductivity measurements for DNA-templated Au nanowires (∼130 nm long, 10 nm diameter, and 40 nm spacing between measurement points) have been made with a technique that utilizes electron beam induced metal deposition to form probe electrodes. Nanowires formed on single DNA origami tiles were demonstrated to be electrically conductive, having resistivities as low as 4.24 × 10–5 Ω m. Wires with Au-Te junctions were also formed, connected and tested. This work demonstrates the creation and measurement of inorganic nanowires on DNA origami templates, and represents important progress toward the fabrication of devices and systems based on self-assembled biological templates.
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