Tuning the Schottky barrier height in single- and bi-layer graphene-inserted MoS2/metal contacts

First-principle calculations based on density functional theory are employed to investigate the impact of graphene insertion on the electronic properties and Schottky barrier of MoS₂/metals (Mg, Al, In, Cu, Ag, Au, Pd, Ti, and Sc) without deteriorating the intrinsic properties of the MoS₂ layer. The results reveal that the charge transfer mainly occurs at the interface between the graphene and metal layers, with smaller transfer at the interface between bi-layer garphene or between graphene and MoS₂. And the tunneling barrier exists at the interface between graphene and MoS₂, which hinders electron injection from graphene to MoS₂. Importantly, the Schottky barrier height ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Φ</mml:mi> <mml:mtext>SB,N</mml:mtext></mml:msub> </mml:math> ) decreases upon graphene insertion into MoS₂/metal contacts. Specifically, for single-layer graphene, the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Φ</mml:mi> <mml:mtext>SB,N</mml:mtext></mml:msub> </mml:math> of MoS₂ contacted with Mg, In, Sc, and Ti are - 0.116 eV, - 0.116 eV, - 0.014 eV, and - 0.116 eV, respectively. Furthermore, with bilayer graphene, when by inserting bi-layer graphene, the negative n-type Schottky barrier of - 0.086 eV, - 0.114 eV, - 0.059 eV, - 0.008 eV, and - 0.0636 eV are observed for MoS₂ contacted with the respective metals, respectively. These findings provide a practical guidance for developing and designing high-performance transition metal dichalcogenide nanoelectronic devices.