MoS₂ Transistors with Low Schottky Barrier Contact by Optimizing the Interfacial Layer Thickness

Molybdenum disulfide (MoS₂) has attracted great attention from researchers because of its large band gap, good mechanical toughness and stable physical properties; it has become the ideal material for the next-generation optoelectronic devices. However, the large Schottky barrier height (Φ_B) and contact resistance are obstacles hampering the fabrication of high-power MoS₂ transistors. The electronic transport characteristics of MoS₂ transistors with two different contact structures are investigated in detail, including a copper (Cu) metal–MoS₂ channel and copper (Cu) metal–TiO₂-MoS₂ channel. Contact optimization is conducted by adjusting the thickness of the TiO₂ interlayer between the metal and MoS₂. The metal-interlayer-semiconductor (MIS) structure with a 1.5 nm thick TiO₂ layer has a smaller Schottky barrier of 22 meV. The results provide insights into the engineering of MIS contacts and interfaces to improve transistor characteristics.