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."
Metal-insulator-metal diodes work by using two different metals with different work functions, allowing electrons to tunnel across the gap very quickly without consuming excess power or generating excess heat.
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.
I am both looking forward to and dreading the onset of computing and communications based on quantum principles. For years I have had a working understanding of pretty much every technology used in modern electronics, but so far that has not helped me to understand how any of this works and how to use it. This is exciting to me because of the potential scale of it while I am also terrified that ultimately I may not understand it. Either way, I can't wait!
That is kind of what I think also... looks like the next shift is quantum physics in regards the semiconductor industry... not that the current don't use quantum science but that it is being used in such new ways that looks like the students of EE will have to have a quantum physics course added to their curricula... I remember I didn't have that. Students ... beware!
Hi Colin. We haven't spoken since I was with Phiar, the company you reference in the above. While quantum tunneling unlocks much higher frequency operation, the seminal question is "who cares?" Near-term, the only mm-wave market of interest seems to be the 60GHz consumer electronics wireless space. SiBEAM and others have credibly demonstrated that silicon CMOS can operate at those frequencies. As your readers know, betting against CMOS is dangerous business...
Further, unless OSU has a working transistor, their diode is destin to remain forever in the lab. The market for discrete, high frequency, square law detector diodes is tiny. Integration atop silicon CMOS in real fabs will be required for MIM electronics to gain real traction.
Happily for students and your readers, the physics aren't as complex as one would think.
Thanks for the interest in this work! If anyone’s interested in more on the science behind the story, including details on how the diodes were constructed and tested, we’ve set the original research article free to access for the next four weeks; you can find it here: http://www.materialsviews.com/details/news/874437/New_Diodes_Quantum_Tunnel_Their_Way_To_Improved_Electronics.html