The combination of thinner circuits and desirable high-K insulation means that these ultrathin semiconductors could be made into transistors 10 times smaller than anything possible with silicon today. 
Silicon is a metal that won't rust easily and is used for some electronic purposes.

Stanford has identified two semiconductors, hafnium diselenide and zirconium diselenide, and are exceeding some of the silicon's strengths. From rusting to electrical circuits, this new material is doing a even better job and more efficient job. This new material can even be shrunk to the size of 3 atoms!

“It’s a bit like rust, but a very desirable rust,” said Eric Pop, an associate professor of electrical engineering, who co-authored with post-doctoral scholar Michal Mleczko a paper that appears in the journal Science Advances. The new materials can also be shrunk to functional circuits just three atoms thick and they require less energy than silicon circuits. Although still experimental, the researchers said the materials could be a step toward the kinds of thinner, more energy-efficient chips demanded by devices of the future."

I gave credit to the orig. owner and placed it in quotations.