Nanowires boost plastic circuits

The move is on to develop flexible, cheap, plastic electronics, but so far organic circuits have fallen far short of silicon chip performance.

Researchers from the Hahn-Meitner Institute in Germany have moved the field forward with a new way to make flexible transistors. The method causes forests of vertical semiconductor nanowires to grow inside a plastic film. The researchers' thin film contains as many as 100 million nanowires per square centimeter.

The researchers made the array of transistors by using an ion beam to etch pores as small as 50 nanometers into a sandwich of metal surrounded by polymer layers, then using electrical current to cause nanowire material dissolved in a solution to solidify into a nanowire at each hole. Fifty nanometers is the span of 500 hydrogen atoms.

The semiconductor nanowires served as transistor channels, the metal layer served as the gate electrode, and the researchers added source and drain electrodes to the top and bottom of the stack to complete the transistors. The gate electrode blocks or allows electricity to flow through a transistor channel.

The researchers are now working with different semiconductor materials to try to boost the nanowire transistor performance. The work appeared in the June 30, 2003 issue of Applied Physics Letters.