Next-generation computing relies on extremely thin semiconductors—now there's a better way to make them

The ability to develop extremely thin semiconductors is key to advancing the fields of electronics and computing. But so far, there's been a trade-off between the quality of these semiconductors and the ability to make them at industrial scale. Prof. Cong Su and his research team have found a solution that combines the best aspects of two methods to make high-quality materials at scale.

The results are published in the Journal of the American Chemical Society.

The importance of monolayer semiconductors

Developing monolayer semiconductors, which transport the current in transistors, is critical to making more powerful electronics and computing devices. Having the thickness of only one atom, monolayer semiconductors are among the thinnest materials possible.

"CPUs are getting more and more powerful because we can shrink the size of transistors," said Su, assistant professor of materials science.

Su and his research team used a method known as chemical vapor deposition (CVD) to synthesize very thin monolayer semiconductors. Typically, the problem with this method, Su said, is that when it's used on a large scale, it produces low-quality crystal.

In conventional methods of CVD using liquid precursors, the precursor (the material from which the monolayers are drawn) is placed in a base solution. But because the ingredients vaporize uncontrollably, atoms in a grown lattice get pulled from the crystal by some byproducts from precursors, which can produce defective, patchy layers.

"We have found a very simple way to make this method scalable," Su said. "Basically, we're changing the environment of the solution from a basic solution to an acid solution."

By pre-treating the chemical ingredients with acid, the researchers successfully anchored them to the surface during growth. "This breakthrough produces record-quality materials, paving the way for faster, highly efficient electronic and quantum devices," Su said.

In fact, he said, the quality of crystal produced is on par with the "Scotch tape method." That method involves applying tape to a commercially available bulk material and then peeling it back, taking with it a thin layer of crystals. While the method is good for producing high-quality crystals and for research purposes, it's not scalable for industry use.

"The biggest breakthrough with this work is that we've reconciled the scalable method that has been widely adopted in the semiconductor fabrication industry with the sample quality," Su said.