Exfoliating and Characterizing mm-Size 2D MoS₂ Films

A technique for exfoliating macroscopic 2D materials is exciting both for building macroscopic devices based on 2D films, and for educational purposes such as use in undergraduate labs and public demonstrations. This project explored methods that would allow a less specialized laboratory to create and study 2D devices. Using only an optical microscope and a thermal evaporator with a shadow mask, mm-size 2D MoS₂ films were exfoliated using two different techniques based on gold films. Electrical contacts with a narrow (10 µm) gap, as well as other structures, were also successfully created in the thermal evaporator using wire to create a shadow mask. The 2D films were transferred with a straightforward dry stamping technique based on PVC films. Gating and charge distribution in the resulting devices were studied using probe microscopy techniques including FM-Kelvin Probe Force Microscopy.