Semiconductor nanowires

Semiconductor nanowires are high aspect ratio wire-like structures that are often referred to as one-dimensional (1D) materials.  The small diameter and cylindrical geometry of nanowires can be exploited to develop unique device structures such as axial and radial heterojunctions where the composition and doping are modulated along the length and/or across the radius of the nanowire.

Our research focuses on the use of vapor-liquid-solid growth for the synthesis of semiconductor nanowires with a special emphasis on the growth and characterization of silicon and silicon-germanium nanowire structures with controlled dopant and compositional profiles.  We seek to understand the effect of nanoscale size on the fundamental mechanisms that control nanowire growth and develop structures for high performance nanowire devices.

We are investigating methods to incorporate silicon nanowires into crystalline silicon solar cell devices to increase the conversion efficiency.  One approach uses an array of high aspect ratio radial junction silicon nanowires as the active region of the solar cell to enhance light absorption and increase photogenerated carrier collection via the short radial junction distance.  In collaboration with Advanced Silicon Group, Inc., we are also investigating the use of silicon nanowires, formed by aluminum-catalyzed vapor-liquid-solid growth, as a p-type antireflective emitter on n-type silicon substrates.

Silicon nanowires synthesized by vapor-liquid-solid growth

Silicon nanowires synthesized by vapor-liquid-solid growth

Si-SiGe axial heterostructured nanowire (courtesy of E.C. Dickey)

Si-SiGe axial heterostructured nanowire  (courtesy of L. Pan and E.C. Dickey)