“We’re coming at this from a completely different angle than what has been done conventionally,” Keszler says. “Ours is a green emphasis. But being green is only one driving force. Performance is another. We want the materials to perform better than what is currently available.”
The center’s early work has drawn upon resources within Oregon State, including its department of chemistry and school of electrical engineering and computer science, as well as the University of Oregon’s department of chemistry. “None of this happens without good chemistry,” Keszler says.
With the new diode, for example, the researchers purify plain tap water and add metal salts with constituents such as hydrogen peroxide—the liquid used medically to treat wounds—to produce specific “nanoclusters,” tiny synthetic compounds that serve as the basis for the inks. “We add these synthetic chemicals and mix them in controlled ways to produce the nanoclusters,” Keszler says.
“We stay away from any elements that are toxic or radioactive,” he adds. “We do a lot of things with zinc, and zinc oxide, aluminum, which is the third most abundant element in the ground around us, and iron, the main component of steel. A lot of these nanoclusters occur in natural water systems, and we are learning more about the behavior of these systems in natural water as well.
“When we print the ink, the water leaves, and the nanoclusters in the inks turn into very high quality films and patterns which function as semi-conductors, insulators, or metals,” he continues. “On almost all of these devices, you need a high-quality insulator that impedes the flow of electrons in order to temporarily store electron energy or act as a gate for controlling movement of electrons through an adjacent semiconductor. That’s extremely hard to do, and what our chemistry does very well.”
Through additional chemical modification, the usefulness of the inks can be extended by making them sensitive to light or electron beams, where they behave like the chemicals in photographic film, Keszler says.
“In this way, the light and beam sources for manufacturing integrated circuits can be used with the inks to pattern very small, complex features with many fewer steps relative to conventional methods,” he says. “The inks give the semiconductor industry a new path to more efficiently manufacture transistors with higher speeds.”