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

Abstract

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 (ΦSB,N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Phi_{{\ ext{SB,N}}}$$\\end{document}) decreases upon graphene insertion into MoS2/metal contacts. Specifically, for single-layer graphene, the ΦSB,N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Phi_{{\ ext{SB,N}}}$$\\end{document} 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.