Researchers find way to make ultra-thin transistors

Researchers at Cornell University have found a new way to make transistors ultra-thin. They coated a silicon surface with a surface area of ​​several square centimeters with a layer of semiconductor material three atoms thick.

The challenge in making usable devices is to uniformly manufacture the billions of transistors on a chip. The team of Jiwoong Park, a chemist at Cornell University, succeeded in making uniform surfaces of a semiconductor material only three atoms thick. 99 percent of the circuits that the researchers made with it worked.

The researchers used a material in the transition metal class dichalcogenides or TMDs as a semiconductor. TMDs are suitable for making transistors, light detectors, solar cells and LEDs, and can also be made in extremely thin layers, with a thickness of only a few atoms. That makes them interesting for future electronics.

Previous studies attempted to obtain very thin layers of the material by stripping layers from a larger piece. Park and his team instead coated a silicon surface measuring several square centimeters with the tmd material. Previous attempts to coat a surface with the material used corrosive and toxic substances, and failed to produce an even coating. Park and his team found a process that uses substances that are relatively safe, which also produces a uniform coating.

The process also enables three-dimensional circuits. When the first layer of semiconductor material is on the chip, more layers can be added. However, a number of problems still need to be overcome before the technology can be used in practice. For example, coating now takes 26 hours at a temperature of 550 degrees Celsius.

Building smaller and smaller circuits is one way to get more transistors on a chip. Chip densities are still doubling every two years, as Gordon Moore predicted in 1975. This development cannot continue without new discoveries that allow transistors to be made smaller.