Complex Nanowires Spontaneously Grown on Graphene
The technology of the future may be quite different from what we are use to today, with the ongoing development of many materials with new and special properties. Among them are nanowires which can have their electrical characteristics determined by controlling what they are made of and their design. Researchers at the University of Illinois, Urbana-Champaign have recently discovered the spontaneous growth of nanowires with differing cores and outer shells.
There are a few ways to grow nanowires and all of them require a substrate for the wires to grow off of. Typically silicon is used for this, but the researchers decided to use graphene, a single-atom thick sheet of carbon, because it is cheaper, flexible, and less of it is needed. Graphene has been used as a substrate for growing nanowires previously, but this experiment differed from those as the nanowires were to be made of indium gallium arsenide (InGaAs); three elements instead of just two. To the researchers' surprise, the elements did not form solid InGaAs nanowires but an InAs core with an InGaAs shell surrounding it. This structure is desired for different applications and usually takes multiple steps, but here it was achieved in one.
Though the researchers did not expect this result, upon further examination they realized what happened. The distance between atoms in a crystal of InAs is roughly the same as a distance within graphene, so the InAs molecules fell into place, while the InGaAs molecules surrounded them.