Wafer-Scale Synthesis of Semiconducting SnO Monolayers from Interfacial Oxide Layers of Metallic Liquid Tin

Atomically thin semiconductors are one of the fastest growing categories in materials science due to their promise to enable high-performance electronic and optical devices. Furthermore, a host of intriguing phenomena have been reported to occur when a semiconductor is confined within two dimensions. However, the synthesis of large area atomically thin materials remains as a significant technological challenge. Here we report a method that allows harvesting monolayer of semiconducting stannous oxide nanosheets (SnO) from the interfacial oxide layer of liquid tin. The method takes advantage of van der Waals forces occurring between the interfacial oxide layer and a suitable substrate that is brought into contact with the molten metal. Due to the liquid state of the metallic precursor, the surface oxide sheet can be delaminated with ease and on a large scale. The SnO monolayer is determined to feature p-type semiconducting behavior with a bandgap of ∼4.2 eV. Field effect transistors based on monolayer SnO are demonstrated. The synthetic technique is facile, scalable and holds promise for creating atomically thin semiconductors at wafer scale.