Technology breakthrough yields ultra-thin transistors

By Gina Roos, editor-in-chief

Researchers at the Vienna University of Technology claim the next big step in miniaturization of transistors, which has been a challenge in keeping up with Moore’s Law. Researchers have developed ultra-thin transistors, with novel insulators, from 2D materials, consisting of an atom-thick layer of material. Exhibiting excellent electrical properties, the new transistor technology can be reduced to a very thin thickness.

Ultra-thin semiconductors can be fabricated from 2D materials with a few atomic layers, said Professor Tibor Grasser, the Institute of Microelectronics at Vienna University of Technology, in a press release. “But if you want to build an extremely small transistor, that’s not enough. In addition to the ultra-thin semiconductor, you also need an ultra-thin insulator.”

A schematic sketch of the ultra-thin transistors (red-blue: the insulator). (Image: TU Wien)

Grasser said that this is due to the fundamental structure of a transistor in which current flows from one side of the transistor to the other if a suitable electric field is generated in the middle by the application of an electrical voltage. Between the electrode and the semiconductor itself is the insulating layer.

To miniaturize this layer and the transistor, the researchers, including Yury Illarionov, a postdoc on Tibor Grasser’s team, used an ultra-thin material — in this case, ionic crystals — for both the semiconductor and insulator, indicating improvements in the electronic properties.

The team decided to use an insulator made of an atomically thin layer of calcium fluoride, produced at the Joffe Institute in St. Petersburg, where Illarionov was a researcher before transferring to TU Vienna. The transistors were manufactured at the Institute of Photonics at the Vienna University of Technology.

Grasser said that the first prototype exceeded their expectations. “In recent years, we have repeatedly received different transistors to investigate their technical properties, but we have never seen something like our transistor with calcium fluoride insulator.”

The team is now working on a combination of insulators and semiconductors to see which will work best, as well as improvements in the production processes for the material layers. They believe that it will likely be several years before the technology can be used for commercial computer chips. The development of these smaller and faster transistors could be the next big step in the computer industry, returning to Moore’s Law of doubling the number of transistors on a chip every two years.

The new technology was first presented in Nature Electronics.