(398b) Semiconductor Nanowires: From Conception to Practice

Semiconductor nanowires are threadlike crystals with nanometer-scale widths and lengths that can extend for millimeters. Their remarkably high surface area-to-volume ratios and nanoscale dimensions give rise to range of unique material properties that might be useful in a variety of new technologies, including printable electronics, solar cells, sensors and fabrics with unprecedented functionality. However, a significant roadblock to the development of semiconductor nanowire technologies has been the lack of production methods capable of producing industrial scale quantities of nanowires. After all, semiconductor nanowires are creations of chemistry-they are not found in nature, and must be synthesized in the laboratory.

During the past decade, we have been working to develop chemical methods capable of producing large quantities of silicon (Si) and germanium (Ge) nanowires with controlled dimensions. Our general approach relies on metal nanocrystals to seed nanowire growth from molecular reactants in a solvent. For example, Si nanowires are made in toluene using colloidal gold nanocrystals and monophenylsilane as a Si source. After nanowire formation, surfaces are modified with organic ligands to provide better chemical stability and improved electronic properties. We have also developed methods to chemically dope these nanowires with electrically-active impurities. The basic synthetic strategies and chemical and engineering lessons learned over the years will be presented, as well as a few examples of how these nanowires are being applied, as in printed nanowire field effect transistors, nanowire electromechanical resonators, and non-woven nanowire fabrics.