Electronic Structure and Edge Modification of Armchair MoS2 Nanoribbons

The geometries and electronic properties of armchair MoS2 nanoribbons were investigated by the first-principles method based on density functional theory. It was found that the stability and electronic properties of armchair MoS2 nanoribbons sensitively depend on edge modification. Increasing the number of hydrogen atoms on the edge caused the nanoribbons to become more stable and transition between indirect-gap semiconductor, semi-metal and direct-gap semiconductor. The band structure and densities of states of the nanoribbons indicated that low energy bands contributed to edge states. Different hydrogen adsorption patterns on each edge induce two kinds of edge state on the nanoribbons and these two kinds of edge state have little effect on each other. The relationships between the bandgap and width of three types of nanoribbons were studied. Nanoribbons terminated with zero or eight hydrogen atoms in each unit cell have a bandgap that oscillates with width in a period of three, while the bandgap changes nonperiodically in those terminated with four hydrogen atoms.