Integrated Nanowire Electronics and Sensors on Flexible Plastic Substrates

Graduate SeminarbyDr. Michael McAlpine
Post-Doctoral Researcher
Division of Chemistry and Chemical Engineering
California Institute of TechnologyAbstractThe introduction of an ambient-temperature route for integrating high performance materials on
flexible plastic substrates could enable exciting avenues in fundamental research, and innovative
electronic and medical devices. However, the temperature constraints imposed by these substrates
restrict the use of high carrier mobility materials, such as polycrystalline silicon, generally limiting these devices to the modest computational capabilities of amorphous silicon and organic semiconductor thin film transistors. The development of new materials and novel materials processes for overcoming this restriction could impact a broad spectrum of applications.Semiconductor nanowires represent unique, high performance building blocks for electronic,
photonic, and sensing devices. In this talk, I will present my work demonstrating that single-crystal
nanowires can be hierarchically assembled onto flexible plastic substrates under ambient conditions to create multi-component, fully integrated devices, including field-effect transistors, light-emitting diodes, ring oscillators, and electronic noses. These devices all exhibit performance metrics which meet or exceed the state-of-the-art for flexible electronics.The key to our approach is the separation of the high-temperature synthesis of single-crystal
nanowires from room temperature assembly, thus enabling fabrication of high-performance devices on
virtually any substrate. Silicon nanowire field-effect transistors on plastic substrates display mobilities rivaling those of single-crystal silicon and exceeding those of amorphous silicon and organic transistors currently used for plastic electronics. Furthermore, we show that these systems can be integrated into ring oscillators on plastic which generate frequencies approaching the microwave, the highest observed frequencies for circuits based on nanoscale materials.Finally, we exploit SiO2 surface chemistries to construct a "nano-electronic nose" library,
which can distinguish acetone and hexane vapours via distributed responses. We also demonstrate that
amide coupling of theoretically tailored peptide sequences to the arrays allows for selective
discrimination of chemicals often found in the breath of sick patients. This excellent sensing
performance coupled with biocompatible plastic could open up far-reaching opportunities in mobile
computing, lightweight display, or even implantable monitoring applications.Thursday, November 15, 2007
12:45 p.m.
OHE 122Refreshments will be served after the seminar in HED Lobby
The Scientific Community is Cordially Invited.

Location: Olin Hall of Engineering (OHE) - 122

Audiences: Everyone Is Invited

Contact: Petra Pearce Sapir