This Scalable NanoManufacturing (SNM) research project will advance the scalable manufacturing of ordered assemblies of carbon nanotubes and of radio frequency electronic devices and systems fabricated from these assemblies. Semiconducting carbon nanotubes are among the best semiconductors that have ever been discovered. They promise to significantly improve the speed, energy efficiency, and sensitivity of a wide range of electronic devices including central processing units (the brains) of personal computers, servers, laptops, and tablets; circuits that send and receive signals for cell phones and communication devices; and sensors such as those employed when screening for diseases or new drugs. The tremendous promise of nanotubes was first discovered 25 years ago, but the field has been held back by materials, processing, and manufacturing roadblocks particularly pertaining to the organization and assembly of aligned arrays of nanotubes. A novel, multiphase fluid process recently discovered by this team called tangential flow interfacial self-assembly with promise for overcoming these roadblocks will be researched in this project. The project is motivated by compelling preliminary results, in which the team has assembled nanotubes into aligned arrays to create field effect transistors (the fundamental building block of electronics) with nearly 10 times higher on-state electrical conductance than previous nanotube transistors' that also exceed the on-state conductance of transistors fabricated from state-of-the-art semiconductors including silicon and gallium arsenide for the first time. In addition to graduate students, underrepresented researchers and undergraduate students from primarily undergraduate institutions will participate in the research effort. The supported graduate students will conduct science-related activities at a local Boys and Girls Clubs and develop new activities via collaboration with an outreach specialist. Local K-12 teachers will also be hosted for summer research experiences.
The overarching goal of the project is to assemble semiconducting nanotubes into aligned arrays that are organized across multiple length-scales and that can be integrated into devices and circuits, via a continuous scalable process. The ideal array microstructure consists of parallel semiconducting nanotubes that are densely packed but individualized at a pitch of 5-10 nanometers. This microstructure needs to be uniformly repeated on the wafer-scale. Our approach for scalably realizing this microstructure will be to hierarchically control the structure and organization of nanotubes via multiple stages of self-assembly. Specific research activities will focus on: (1) designing and tailoring the structure of polymer-nanotube conjugates to improve the Nano-, micro-, and millimeter-scale uniformity and reproducibility of ordered nanotubes arrays; (2) uncovering the fundamental factors that control the assembly of nanotubes during the recently discovered tangential flow interfacial self-assembly process; (3) scaling this process; and, (4) integrating assembled nanotube arrays into complex devices, circuits, and systems for next-generation radio frequency communications technologies. At the project's conclusion, the PI aims to provide: (i) a pilot-scale instrument for the continuous deposition of aligned nanotube arrays with exquisite control over microstructure; (ii) the first example of a uniform, densely aligned array of semiconducting nanotubes on the 200 mm wafer-scale - a scale relevant for commercialization; and, (iii) performance-superior radio frequency low-noise amplifiers and mixers fabricated from these arrays and wafers, of relevance for next-generation cellular, WiFi, and Internet of Things technologies.
