Contact Resistance Reduction in 2D MoS₂ FETs Through the Thermal-Evaporated LiF Interlayer

Molybdenum disulfide (MoS₂) is most promising n-type two-dimensional (2D) transition metal dichalcogenide semiconductors for nanoscale electron devices. But, issues still remains in the 2D device and relatively high contact resistance is one of them. Although many scientific approaches have been made to obtain a record-low R_C, a practical and reliable technique should also be developed. Here thermal-evaporated ultrathin LiF is inserted between MoS₂ and source/drain metal to achieve minimum R_C in 2D-like MoS₂ field effect transistors (FETs). The R_C from the MoS₂ FET with LiF/Au contact is less than ∼600 Ω μm as measured by 4-bar method. The mobility measured from 2-bar FET scheme reaches that from 4-bar FET scheme which exclude mobility degradation from contact resistance. Furthermore, ultrathin LiF is compatible with ITO conductive oxide so that transparent MoS₂ FETs can be fabricated.