One-atom-thick germanium sheets could replace silicon in semiconductors
By Ben Coxworth
April 12, 2013
It consists of one-atom-thick sheets and it could revolutionize electronics ... but it’s not graphene. Chemists at Ohio State University, instead of creating graphene from carbon atoms, have used sheets of germanium atoms to create a substance known as germanane. Because of its numerous advantages over silicon, it could become the material of choice for semiconductors.
Germanium was used to create the first experimental microchips over 60 years ago, and Ohio State assistant professor of chemistry Joshua Goldberger wondered if it could still give graphene a run for its money. “Most people think of graphene as the electronic material of the future,” he said. “But silicon and germanium are still the materials of the present. Sixty years’ worth of brainpower has gone into developing techniques to make chips out of them. So we’ve been searching for unique forms of silicon and germanium with advantageous properties, to get the benefits of a new material but with less cost and using existing technology.”
The resulting material has been shown to conduct electrons ten times faster than silicon (and five times faster than conventional germanium), meaning that it could carry a proportionately higher load if used in microchips. It’s also more chemically stable than silicon, not oxidizing in the presence of air or water, plus it’s much better at absorbing and emitting light – this means that it could prove particularly useful in solar cells.
Scientist have created germanane before, although apparently never in sufficient quantities to conduct such an extensive study of its properties, or to allow for large-scale production. To make their germanane, Goldberger and his team took a unique approach.
Ordinarily, germanium takes the form of multilayered crystals. The single-atom-thick layers are bonded to one another, and each one is quite unstable on its own. The OSU researchers created their own germanium crystals, in which calcium atoms were inserted between the layers. That calcium was then dissolved using water, leaving empty chemical bonds in its absence. Those bonds were subsequently plugged with hydrogen, resulting in much more stable layers that could be peeled from the crystal while remaining intact.
Goldberger and his team now plan on investigating how the material’s properties could be tweaked, by changing the configuration of the atoms within a single sheet.
A paper on the research was recently published in the journal ACS Nano.
Source: Ohio State University