Researchers at the Nano-Science Center of the University of Copenhagen, Denmark, have developed a way to produce ultra-clean nanowires, overcoming one of the challenges to the production of such materials – controlling the production so the electronic structure is perfectly uniform throughout the nanowire.
The new nanowires will have a central role in the development of new high-efficiency solar cells and electronics on a nanometer scale. Peter Krogstrup, a PhD student, said “[T]he ultra-clean wires are grown on a silicon substrate with an extremely thin layer of natural oxide. The element Gallium, which is a part of the nanowire material, reacts with the oxide and makes small holes in the oxide layer, and here the gallium collects into small droplets of a few nanometers in thickness. These droplets capture the element Arsenic — the other material in the nanowire and through a self-catalytic effect starts the growth of the nanowires without interference from other substances.” Since the nanowires are grown on a silicon substrate, which is cheaper than alternative substrates, a high efficiency solar cell based on these nanowires will be more cost effective. “The substrate is cheaper than the alternative substrates that many other researchers use. It is important because ultimately it is about getting as much energy as possible for as little cost as possible,” explained Krogstrup.