Researchers claim better 'quantum tunneling'

R Colin Johnson

November 1, 2010

R Colin Johnson

PORTLAND, Ore.—Researchers at Oregon State University (OSU)claim to have perfected a better method for "quantum tunneling" using metal-insulator-metal (MIM) architecture, potentially paving the way for faster, lower power and cooler running electronics.

Quantum tunneling offers advantages over traditional current flow, in which electrons jump across device barriers rather than traversing through them, slowing down the flow, increasing power requirements and generating excess heat. Traditional tunneling diodes use a heavily doped p–n junction which has limited their use to discrete devices.

A MIM diode uses two different metals with different work functions, separated by an insulator, resulting in a ballistic transport mechanism that accelerates electrons from one metal contact to the other.  In 2007, Phiar Corp. (Boulder, Colo.) demonstrated an experimental MIM diode that operated at frequencies as high as 3.8 THz, but the project was reportedly scrapped due to yield problems in transferring the technology out of the lab and into the commercial marketplace. OSU, on the other hand, claims to have solved potential yield problems by using an amorphous, instead of crystalline, metal contact.

"Our approach should provide a solution to yield problems, while also enabling low-temperature fabrication," said Douglas Keszler, an OSU professor. "It also provides a means to readily tune the properties of tunneling devices."

The new MIM fabrication method using amorphous metals can be perform at relatively low temperatures, according to Keszler, opening the possibility of using MIMs for large-area displays and other printable electronic devices. The devices can be made with a variety of different metals including copper, nickel or aluminum.

Next the researchers plan to adapt their technique to three-terminal tunneling transistors similar to those being proposed by the European Union's Steep Program.

Funding for the project was provided by the National Science Foundation, the Army Research Laboratory and the Oregon Nanoscience and Microtechnologies Institute.