This Phase I CCI focuses on the important question of how to use molecules to replace bulk materials as components in integrated circuits (IC's). The dramatic improvements of electronic device performance have been a direct consequence of steady improvements in "top-down" methods to fabricate IC's, but feature sizes are rapidly approaching the limits of traditional lithographic methods. In addition, device improvements have not scaled with the latest generations of line-width improvements and new ways to carry out computation and data storage are being explored. Molecular electronics, which substitute nanoparticles and molecule based structures in place of bulk materials currently used in IC's, offer the potential to address these challenges. Unleashing this potential will require new fabrication methods that allow control of the location, dimension, and orientation at the molecular level. The initial focus of the Phase I Center for Nanostructured Electronic Materials is research in 2D directional growth with novel use of chemical precursors and synthetic methods, such as surface plasmon-mediated chemical deposition (SPMCD) that exploits the optical properties of nanoparticles for selective growth of material at specific locations. The non-destructive fabrication of electrical contacts (junctions) between juxtaposed molecular electronic components will be approached by electron beam induced dissociation (EBID) and electrodeposition of contact materials. The research will be extended to 3D growth techniques where specific chemical interactions, involving self-assembled monolayers and tailored chemical precursors, can be applied to induce preferential growth in the z direction. The size and proximity of the nanostructures explored in this program will enable the unprecedented utilization of quantum confinement, coulomb charging and proximal optical coupling for fabrication of potentially new nanoelectronic and nanophotonic devices. This CCI will foster close collaborations between experts in the development of new nanoscale electronic materials and specialists in the creation of prototypes with direct technological relevance. Participants at the University of Florida, University of Illinois at Urbana-Champaign and the University of Georgia will collaborate with industrial mentors from companies on the forefront of development of molecular electronics, who will provide an industrial perspective on materials requirements, device design and manufacturing.
The focus of the Center for Nanostructured Electronic Materials on chemistry-based approaches to molecular electronics for applications in the microelectronics industry is a crucial component of America's competitive edge in technology. Such innovation would aid US national economic competitiveness as articulated in the American Competitiveness Initiative. Within this context, the center will educate students for interdisciplinary collaborative work by building team-based problem solving skills that reach outside the students' own disciplines. Internships, mentoring of undergraduate researchers, and interactions with industrial research personnel will be used to further broaden the students' perspectives. In order to communicate the excitement of science to the general public, the CCI will develop a series of two-minute radio spots and podcasts that will feature real world applications of chemistry and materials science research. To enable broader participation by under-represented groups, the CCI will partner with the established broadening participation programs of the three universities participating in this CCI to recruit and mentor minority and female undergraduates and Ph.D. students.
The Centers for Chemical Innovation (CCI) Program supports research centers that can address major, long-term fundamental chemical research challenges that have a high probability of both producing transformative research and leading to innovation. These Centers will attract broad scientific and public interest by sharing the results of their innovative approach to this challenging question.
This Phase I Center for Chemical Innovation focused on the important question of how to use molecules to replace bulk materials as components in integrated circuits. Unleashing this potential will require new fabrication methods that allow control of the location, dimension, and orientation at the molecular level. Experiments addressed strategies to organize and connect molecules and other nanoscale objects into functional integrated circuits (ICs) with reduced size and vastly improved performance. Professors Wei and McElwee-White developed a new deposition method, called surface plasmon-mediated chemical deposition (SPMCD), to fabricate interconnected nanostructures with molecular level control. The technique uses visible light to raise the local temperature of nanostructure features and exploits the resulting temperature differences to promote localized chemical depositions at the "hot spots" on the surfaces of the nanostructures. Under the right conditions, the depositions may be directed to grow wires that will link the nanostructures into arrays. A process for nanotube nanosoldering, was developed by Professors Girolami and Lyding. Nanotube nanosoldering is a chemistry based method to improve the performance of field effect transistors fabricated from arrays of carbon nanotubes. These transistors are very easy to fabricate, and thus quite appealing, but their performance suffers due to the fact that the current flow must traverse highly resistive nanotube-nanotube junctions during operation. Nanotube nanosoldering takes advantage of the high nanotube-nanotube junction resistance by recognizing that local heating will occur at these junctions during current flow. This heating can then be used to drive a local chemical reaction, such as a metal chemical vapor deposition (CVD) reaction, to encase the resistive junction in low resistance metal and solder the connection. Electrochemical methods were used by Professor Lay to lower the electrical resistance in 2-dimensional arrays of single walled carbon nanotubes (SWNTs). This involved depositing copper nanoparticles onto the SWNTs to increase electrical conductivity through the arrays, while maintaining the semiconductive properties of the nanotubes. Copper nanoparticles with sizes ranging from 5 to 20 nanometers were found to provide optimal increases in electrical conductivity without significantly reducing the performance of SWNT arrays in field-effect transistors. This technique allows performance enhancement of SWNT-based materials by avoiding damage to the π-bonding network that gives nanotubes their fascinating properties, while concurrently increasing electrical transport across junctions between the SWNTs in an array. Public Outreach: In conjunction with the University of Florida public radio station WUFT-FM, CNEM produced the radio series Tiny Tech, which is a set of 90-second radio modules devoted to the chemistry of nanotechnology. Broadcasting of the modules on WUFT began on September 30, 2011 and as of August 31, 2014, 32 different episodes had been aired. Audio (mp3) files and the scripts are available in the archives at tinytechradio.org. The archive can also be reached through the local programming link at www.wuftfm.org/. Podcasting of Tiny Tech began in Year 3, and the entire series is available on the iTunes store.
