"Now scientists in China have created a transistor using graphene and molybdenum disulfide with a gate length of just 0.34 nm by exploiting the vertical aspect of the device. “We have realized the world’s smallest gate-length transistor,” says study senior author Tian-Ling Ren, an electrical engineer at Tsinghua University in Beijing."
These Transistor Gates Are Just One Carbon Atom Thick Researchers may have hit a hard limit
https://spectrum.ieee.org/smallest-transistor-one-carbon-atom