Laser Method Yields Single-Atom-Thick Molybdenum Sulfide

A laser-based technique can make one-atom-thick layers of molybdenum disulfide, possibly enabling large-scale production of electronics based on the semiconductor (Nano Lett., DOI: 10.1021/nl301164v). Single-atom-thick MoS₂ has a band gap—the energy difference between a conducting state and a nonconducting one—greater than silicon’s. As a result, transistors made from the material would require less power to turn off than silicon-based ones do. Researchers think the flexible and transparent material could be an alternative to silicon in bendable displays and electronics. Currently, methods to make single-atom sheets of MoS₂, such as exfoliating chunks of the material using sticky tape, are too cumbersome for large-scale production. Andres Castellanos-Gomez, a researcher at Delft University of Technology, in the Netherlands, found that when he shined a 10-mW green laser beam on multilayer MoS₂ flakes, the material’s top layers vaporized. He and his colleagues used optical microscopy, atomic force microscopy, and Raman spectroscopy to confirm that the remaining material was a single layer of atoms. They produced transistors using the material and found that the devices had switching speeds similar to those of transistors made from exfoliated single-layer flakes.