Improved Contacts and Device Performance in MoS₂ Transistors Using a 2D Semiconductor Interlayer

We report a contact engineering method to minimize the Schottky barrier height (SBH) and contact resistivity of MoS₂ field-effect transistors (FETs) by using ultrathin 2D semiconductors as contact interlayers. We demonstrate that the addition of a few-layer MoSe₂ between the MoS₂ channel and Ti electrodes effectively reduces the SBH at the contacts from ∼100 to ∼25 meV, contact resistivity from ∼6 × 10^-5 to ∼1 × 10^-6 Ω cm², and current transfer length from ∼425 to ∼60 nm. The drastic reduction of SBH can be attributed to the synergy of Fermi-level pinning close to the conduction band edge of the MoSe₂ interlayer and favorable conduction-band offset between the MoSe₂ interlayer and MoS₂ channel. As a result of the improved contacts, MoS₂ FETs with Ti/MoSe₂ contacts also demonstrate higher two-terminal mobility.