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Electrical Engineers Developing Super Energy-Efficient Microelectronics

New Technology Uses Nanotransistors

UMass Lowell Image
From left, Prof. Martin Margala, Vikas Kaushal and Ignacio de la Torre from the Universidad de Salamanca in Spain working in the lab on the design of a “ballistic deflection transistor.”

By Edwin L. Aguirre

As smartphones, tablets and other mobile devices become increasingly popular, finding ways to make them even smaller in size, run a lot faster and consume far less power has become the holy grail for semiconductor researchers worldwide.

Electrical engineering Prof. Martin Margala, together with his former graduate student Vikas Kaushal and collaborators from the Universidad de Salamanca in Spain and North Carolina State University, are moving one step closer to achieving that goal with their work on “ballistic deflection transistors,” or BDTs. These unique, super-fast nanochips will form the building blocks for the next-generation ultrahigh-speed computers and electronic circuits.

“Such a nanotransistor would operate a thousand times faster — in the terahertz range — and consume extremely low power and generate far less heat compared to conventional transistors,” says Margala, a senior member of the Institute of Electrical and Electronics Engineers (IEEE) and chair of UMass Lowell’s Electrical and Computer Engineering Department.

Instead of starting and stopping the flow of electrons the way standard transistors do, the BDT design uses electrical fields to “steer” individual electrons and bounce them off deflectors, in a form of atomic billiards or pinball arcade game.

“Ballistic deflection transistors should be easy to mass-produce using current technologies,” says Margala. “They have the potential to revolutionize modern electronics.”

Enhancing the Nanotransistors’ Performance

Margala and his co-researchers were able to make the nanotransistors perform even better by depositing an ultrathin, uniform layer of aluminum oxide, Al2O3, to the walls of the etched trenches in BDTs. 

“By using the Al2O3 as an insulator instead of just air as before, we significantly improved the nanotransistor’s gate-control sensitivity,” explains Margala. “This means the nanotransistor could achieve peak performance at much lower power.”

The group’s findings were published in a recent issue of the journal “IEEE Electron Device Letters.”

Margala says ultimately, they will be able to reduce power consumption even further and operate the BDT at very low voltages. 

“This will make our nanotransistor unique for commercial applications that operate with very limited power sources yet require very high performance,” he says. “This includes all mobile devices, portable medical sensors, implants and other devices, as well as various electronics for deep-space missions.”

Margala’s research on BDTs actually began in 2005, while he was with the University of Rochester. Since he joined UMass Lowell in early 2007, he has continued his work in this field, receiving funding mainly from the Air Force Office of Scientific Research. In 2009, he received a $101,000 grant from the National Science Foundation (along with $40,000 from UMass Lowell) to purchase a multi-probe, wide-temperature parameter analysis system for measuring low voltages and low noises.

Margala received his master’s degree in microelectronics from Slovak Technical University in Bratislava, Slovakia, in 1990, and his Ph.D. in electrical and computer engineering from the University of Alberta in Edmonton in 1998. Kaushal graduated from UMass Lowell in 2011 with a doctorate in electrical engineering and now works at IBM in Burlington, Vt.