First-principles study on electronic properties of monolayer MoS₂ with X₃(X = Cu, Ag, Au) cluster adsorbing

In this work, the structural stabilities, band structures and densities of states of monolayer MoS₂ adsorbed with X₃ (X = Cu, Ag, Au) clusters are studied by first principles method. It is found that the stability of monolayer MoS₂ adsorbed with Cu₃, Ag₃ or Au₃ cluster in the S position is stronger than that in the Mo position; 3 impurity levels related to the donor and acceptor levels formed by covalent bonds between X₃ and S atoms are emerged in the adsorption systems. The metallic properties of Cu, Ag, and Au lead to the transition of monolayer MoS₂ to conductors. The densities of states of the adsorption systems are mainly derived from Mo 3s, S 5s and 3d, 4d and 5d orbitals of, respectively, Cu, Ag and Au in the low energy region. The d orbitals of Cu, Ag and Au are hybridized with the p orbitals of S, and a higher peak of density of states is formed in the range from -7.5 eV to -1 eV. At the same time, the charge distribution is mainly in the directions of Mo-S, Cu-S, Ag-S and Au-S bonds near the Fermi energy. (authors)