Semiconducting nanowires

The team from IBM, Purdue University and the University of California at Los Angeles has learned how to create nanowires with layers of different materials that are sharply defined at the atomic level, which is said to be a critical requirement for making efficient transistors out of the structures.

‘Having sharply defined layers of materials enables you to improve and control the flow of electrons and to switch this flow on and off,’ said Eric Stach, an associate professor of materials engineering at Purdue.

Electronic devices are often made of ‘heterostructures’, meaning they contain sharply defined layers of different semiconducting materials, such as silicon and germanium. Until now, however, researchers have been unable to produce nanowires with sharply defined silicon and germanium layers. Instead, this transition from one layer to the next has been too gradual for the devices to perform optimally as transistors.

The new findings point to a method for creating nanowire transistors. Whereas conventional transistors are made on flat, horizontal pieces of silicon, the silicon nanowires are ‘grown’ vertically. Because of this vertical structure, they have a smaller footprint, which could make it possible to fit more transistors on an integrated circuit, or chip, Stach said.