Lab aims for superconducting FET

May 09, 2011 // By R. Colin Johnson
The resistance of superconductivity to rational explanation has prompted the U.S. Department of Energy's (DoE) Brookhaven National Laboratory to fabricate atomically perfect ultra-thin-films capable of accurately characterize the transition from an insulator to superconductor.

A normally insulating copper-oxide material (cuprate) was configured like the channel of a field-effect transistor (FET), using molecular beam epitaxy to create an atomically perfect superconducting film. So far the researchers have demonstrated that an external electric field can tune the temperature at which the material superconducts by as much 30 degrees Kelvin, a tenfold increase over previous reported results, according to principle researcher on the project, Ivan Bozovic.

According to Bozovic, the millimeter scale of their material also makes it one of the few examples of quantum-mechanical behavior at the macroscopic sample. His team has also found evidence that the Cooper-pairing of electrons, necessary for superconductivity, actually precedes the transition, and that their films exhibit the exact resistance predicted by quantum mechanics when they transition to superconductivity, namely 6.45 kilo-ohms (Planck's quantum constant divided by twice the electron charge squared).

"As we continue to explore these mysteries, we are also striving to make ultrafast and power-saving superconducting electronics a reality," said Bozovic.

Brookhaven physicist Ivan Bozovic wants to understand why a thin-film insulator transitions to the superconducting state.Source: Brookhaven National Labs.

Superconducting FETs would be faster, lower power and could be packed more densely than conventional transistors today, plus could have novel new operation modes such as the ability to modulate superconductivity with an external electric field.

"This is just the beginning," Bozovic said.

Funding for the project was provided by the DoE's Office of Science and the Swiss National Science Foundation.