'Tunable Diode' A New Tool For Engineers

As reported in the Dec. 19 issue of Science magazine, Mark Lonergan has demonstrated the concept of a “tunable diode,” a new type of electronic device for controlling electricity.

The appearance of the article in this prestigious publication comes almost exactly 50 years after the discovery of the transistor by three researchers, one of whom, the late Walter Brattain, earned a master’s degree from the University of Oregon in 1926. Brattain and his collaborators, John Bardeen and William Shockley, jointly received the 1956 Nobel Prize in physics.

Lonergan’s realization of the tunable diode relies on the special properties of a relatively new class of materials known as conducting polymers. Presently, there is no direct analog to the tunable diode based on more conventional materials.

“The unique properties of this device hopefully will open new avenues for electrical engineers in the design of circuitry for the useful control and manipulation of electrical energy,” Lonergan says.

The manipulation of energy in electrical circuits can be likened to the control of traffic on a highway system. In each case, specialized structures exert control over the system’s traffic. Conventional diodes can be viewed as one kind of traffic control device--essentially a one-way street for electricity. The tunable diode remains a one-way street, but it offers the added flexibility of a variable number of lanes.

Specific applications of the tunable diode and its unique characteristics have yet to be devised. Lonergan notes, however, that “if the concept of the tunable diode can be successfully transferred into a practical device, it may one day join the transistor, resistor and capacitor as a common component found in a myriad of new electronic devices. It is a new tool, and the advent of any new tool opens new possibilities.”

Lonergan joined the UO chemistry faculty in 1996 as an assistant professor. Originally from Hillsboro, Ore., he attended the University of Oregon as an undergraduate, earning degrees in mathematics and chemistry with summa cum laude honors in 1990.