Nanowire growth

Our nanowire growth activity is focused on fabricating specific nanowires for later integration into electronic devices such as field-effect-transistors. Specifically we are concentrating on group IV (Si & Ge) and, most recently, on III-V nanowires.

In our project, we use two approaches to fabricate nanowires. The first method relies on patterning a resist layer using electron lithography, followed by dry etching. This is very similar to processes used today in semiconductor manufacturing. In contrast, the second method relies on a process called vapor-liquid-solid (VLS) growth [1,2]. Here, a metal particle is used as catalytic seed to promote the growth of a nanowire. During VLS growth, the metal particle first forms a eutectic melt with a semiconducting material, such as silicon, that is supplied from the gas phase. After reaching a critical silicon concentration in the liquid seed, a solid crystal having a similar diameter as the seed particle precipitates out from the seed. Seed particles are predominantly small colloidal gold particles with diameters down to a few nanometers that can be synthesized using wet chemistry. Whereas colloidal Au particles are simple to synthesize, their controlled placement on substrates was only recently achieved [3]. Alternatively, nanowires can be grown from gold dots that are patterned using electron lithography and metal deposition techniques as shown in the figure at right [4]. Nanowires that grow epitaxially on a substrate are particularly well suited for subsequent device integration [5,6,7].

 References