Carrier gas effects on aluminum-catalyzed nanowire growth.

Aluminum-catalyzed silicon nanowire growth under low-pressure chemical vapor deposition conditions requires higher reactor pressures than gold-catalyzed growth, but the reasons for this difference are not well understood. In this study, the effects of reactor pressure and hydrogen partial pressure on silicon nanowire growth using an aluminum catalyst were studied by growing nanowires in hydrogen and hydrogen/nitrogen carrier gas mixtures at different total reactor pressures. Nanowires grown in the nitrogen/hydrogen mixture have faceted catalyst droplet tips, minimal evidence of aluminum diffusion from the tip down the nanowire sidewalls, and significant vapor-solid deposition of silicon on the sidewalls.

Microstructured optical fibers as high-pressure microfluidic reactors.

Deposition of semiconductors and metals from chemical precursors onto planar substrates is a well-developed science and technology for microelectronics. Optical fibers are an established platform for both communications technology and fundamental research in photonics. Here, we describe a hybrid technology that integrates key aspects of both engineering disciplines, demonstrating the fabrication of tubes, solid nanowires, coaxial heterojunctions, and longitudinally patterned structures composed of metals, single-crystal semiconductors, and polycrystalline elemental or compound semiconductors within microstructured silica optical fibers.