Remembering Professor Emeritus John Tucker
No matter the project, even the most heralded electronic devices are based on fundamental, well-established theories. There are basic tenants like Ohm’s law, taught in high-school physics classes, and there are concepts like the Tucker Theory, which is complex, yet essential for certain applications. The latter is named for Professor Emeritus John R. Tucker, who passed away in April, leaving an exceptional research legacy that bridged the boundary between theoretical physics and circuit development.
The significance of the Tucker Theory can be sensed best, perhaps, when looking at photos of the Atacama Large Millimeter/submillimeter Array, which is perched high on a sundrenched plateau in the Chilean Andes. Comprising more than 60 radio-frequency receivers, each resembling massive satellite dishes, this site is the most powerful telescope for observing the universe. Tucker’s theoretical framework made this equipment possible.James J. Coleman, who was a colleague of Tucker. “His predictions allowed others to build the hardware that helped dramatically change our understanding of the universe.”
Tucker’s theory led to the development of superconductor-insulator-superconductor mixers, which can detect and amplify radio frequencies with wavelengths less than a millimeter. By collecting these signals, astronomers are able to construct space images with much more clarity and depth than optical telescopes.
Before Tucker developed his theory, the radio-frequency receivers only detected much longer wavelengths. The submillimeter wavelengths were too noisy for analysis. Tucker, however, theorized that the signal could be amplified and the noise practically eliminated by using a process known as quantum tunneling. His predictions proved correct, and between 1978 and 1985, he developed the theory that now bears his name. From that breakthrough, the whole field of submillimeter astronomy resulted.
“While many people think about making progress with what we have today, John would think about what would sustain us 10, 20, 30 years from now,” said Professor Ravishankar K. Iyer, who then directed the Coordinated Science Laboratory where Tucker was a researcher. “More than one person, in fact, has remarked to me that John Tucker was of Nobel quality.”
Beyond his groundbreaking theory, Tucker was also interested in the development of quantum computers, which could dramatically accelerate computation speeds using novel components based on quantum-scale properties. To move toward this goal, Tucker focused his research on semiconductor fabrication. He and collaborators developed a new dopant patterning process, which he later employed in 3-D epitaxial integrated circuits. In 2001, he established the Center for Quantum Computers at Illinois to focus on these developments.
“We all talk about a computing wall, and John made some remarkable new discoveries that would allow a whole new generation of devices to be developed,” Iyer said.
Tucker also proposed gate-induced tunneling as a means of developing metal-oxide-semiconductor transistors with gate lengths smaller than 25nm. Based on their results, research teams in industry and academia began competing to develop smaller devices, beginning in the mid 1990s. Within the past five years, two start-up companies were working in the United States to further advance these techniques.
“There are just people who are gifted,” said Professor J. Gary Eden who recalls meeting Tucker during frequent conversations around the coffee pot in the former Electrical Engineering Research Laboratory. “They have the ability ... to see the theoretical underpinnings of a problem. They just see it in their mind’s eye. ... John was gifted in that way.”
Tucker joined the ECE ILLINOIS faculty in 1981, having caught the attention of Professor John Bardeen, the two-time Nobel Prize winner who worked at the same nexus of theoretical physics and circuit development. In fact, it is Bardeen’s theory of superconductivity—recognized by his second Nobel Prize—which underlies the Tucker Theory.
Tucker was named a Fellow of the American Physical Society in 2002 and received the IEEE Microwave Pioneer Award the same year. In 2008 and 2009, he served as the chairman of the MicroDevices Laboratory Visiting Committee at NASA’s Jet Propulsion Laboratory.
“It became apparent very quickly,” Eden said of their early conversations, “that this man—the only word I can think of—was just brilliant.”