Researchers discovered a family of two-dimensional semiconductors that could open the path for energy efficient electronics.
We are fitting more and more transistors in a single chip, thanks to ever decreasing size of transistors, some of which are so small that millions of them can be crammed onto a chip. But as the trend of miniaturization continues, silicon material is reaching its limit of performance. Shrinking a silicon-based transistor too small can lead to highly uncontrollable device behaviors due to quantum tunneling effects.
2D semiconductors are promising candidates for replacing silicon. These materials are few atoms thick, and because of this nanoscale size, such materials are strong contenders as replacements for silicon in the quest of developing compact electronic devices. However, these materials are pestered by high electrical resistance when they come into contact with metals.
Researchers from the Singapore University of Technology and Design (SUTD) have discovered a family of two-dimensional (2D) semiconductors could pave the way for high-performance and energy-efficient electronics.
“When you form a contact between metal and semiconductor, often there will be what we call a Schottky barrier,” explains SUTD Assistant Professor Ang Yee Sin, who led the study. “In order to force electricity through this barrier, you need to apply a strong voltage, which wastes electricity and generates waste heat.”
Therefore the team looked towards ohmic contacts or contacts with no schottky barriers. They discovered a family of 2D semiconductors, namely MoSi2N4 and WSi2N4, form Ohmic contacts with the metals titanium, scandium and nickel, which are widely used in the semiconductor device industry.
Furthermore, they observed that the new materials are free from Fermi level pinning (FLP), a problem that severely limits the application potential of other 2D semiconductors.
“FLP is an adverse effect that happens in many metal-semiconductor contacts, and is caused by defects and complex materials interactions at the contact interface,” Ang said. “Such an effect ‘pins’ the electrical properties of the contact to a narrow range regardless of the metal used in the contact.”
Researchers believe that their work may lead to the fabrication of semiconductor devices applicable in mainstream electronics and optoelectronics—and even potentially replace silicon-based device technology altogether.
The research appeared in the journal npj 2D Materials and Applications.