Telluriding monolayer MoS2 and WS2 via alkali metal scooter
A sodium ‘scooter’ speeds along the making of new two-dimensional semiconductors
Ultrathin semiconductors can be made by sandwiching a layer of transition metal atoms, such as molybdenum (Mo) between layers of either sulphur (S), selenium (Se) or telluride (Te) atoms. Swapping atoms in the outer layers with one of the other elements, for example S to Se or vice versa, creates new electronic properties, but converting S or Se to Te is tricky as MoTe2 breaks up at 700°C – lower than the temperature required for the conversion reaction. A team including researchers from the Institute for Basic Science grew wafers of molybdenum disulfide (MoS2) and used a sodium (Na) ‘scooter’ to carry Te to replace S. The Na-scooter catalysed the reaction and reduced the reaction temperature to 525°C, creating a stable MoS2-Te2 alloy.
This speedy conversion technique could be used to fine tune the electrical properties of ultrathin semiconductors.
- Nature Communications 8, 2163 (2017). doi: 10.1038/s41467-017-02238-0