Semiconductor advance paves the way for faster electronics

Researchers from Tohoku University, Cambridge University and the National Institutes for Quantum Science and Technology have demonstrated a new way to make a material known as tin sulfide (SnS), which can help build better and more compact electronic devices. The method can grow SnS in sheets so thin that they are comprised of one layer of atoms. This strategy could streamline the process of making SnS.

Makoto Kohda, a researcher from Tohoku University, said SnS is special because it can conduct electricity and respond to light in unique ways. “Our method makes it easier to study those unique properties, which are important because they could lead to faster, more efficient computers,” Kohda said.

Spin-valleytronics is an area of research that utilises both the “spin” and “valley” of tiny electron particles inside a computer with the aim of developing electronics with high efficiency. While SnS has many desirable traits, it is also challenging to selectively form SnS from base tin (Sn) and sulfur (S), as it may sometimes produce SnS₂ instead. To ensure the material produced is correct, the researchers developed an easier and safer process that can reliably produce ensure sheets of SnS.

The researchers found that heating sulfur and tin in the right way can grow pure, high-quality SnS crystals on ordinary silicon wafers. A computer-calculated phase diagram predicted that low sulfur levels should give SnS, while high sulfur levels should give SnS₂. The researchers tested that prediction in the lab by sliding the sulfur source closer or father from the tin. Then, the researchers used operando scanning electron microscopy to watch the outer layers “sublime” away (going directly from a solid to a gas), leaving a monolayer film behind.

“Our findings could speed up how scientists discover and understand new physical effects using monolayer SnS,” Kohda said.

Linking together three research areas – ferroelectrics, spintronics and valleytronics – opens the door to creating better electronics, especially those that use light and tiny spins to work faster and smarter. The research findings have been published in the journal Nano Letters.

Image credit: Tohoku University