If you're looking to a future of ever more affordable electronics and pervasive-computing applications, look through a thinner film. The March 18 issue of the technical journal Nature includes a report from researchers at IBM's T.J. Watson Research Center in Yorktown Heights, N.Y., who Big Blue says have made a big step toward making easily and cheaply manufactured semiconducting materials for everything from smart cards to flexible displays.

While other CPU scientists focus on etching ever smaller, more sophisticated transistors onto silicon crystals, IBM Research team leader David Mitzi's group works on the other end of the electronic spectrum: inventing extremely low-cost methods for producing high volumes of relatively simple devices, such as electronics sprayed onto molded plastic shapes.

Mitzi's specialty is spin coating -- a technique as simple as a carnival paint spinner, in which several drops of a liquid solution are placed onto a spinning platter so centripetal forces will spread the liquid to a uniform thickness. The liquid is then cured into a thin film that can accommodate transistors and other electronic devices.

Points in the Paint

Until now, the only semiconductor materials that could be made with spin coating suffered from low charge mobility -- electrical charges couldn't move through the film very fast, so electronic circuits made from it didn't work exceptionally well. The Watson Research Center team found a new way to dissolve higher-mobility semiconducting materials, combining semiconducting metal chalcogenide molecules and the formerly poor-performing solvent hydrazine (a highly energetic molecule also used as rocket fuel) with extra chalcogen -- oxygen, sulfur, selenium, or tellurium -- atoms.

The latter proved to improve the solubility of the liquid, while evaporating -- along with the hydrazine -- when the resulting film is heated, leaving just a thin (as thin as 5 nanometers) layer of conducting chalcogenide. The result is charge mobility approaching that of more pricey polycrystalline silicon -- 10 times the electrical-charge flow of any previously spin-coated material.