Strain-tunable electronic and transport properties of MoS₂ nanotubes

Using density functional theory calculations, we have investigated the mechanical properties and strain effects on the electronic structure and transport properties of molybdenum disulfide (MoS₂) nanotubes. At a similar diameter, an armchair nanotube has a higher Young's modulus and Poisson ratio than its zigzag counterpart due to the different orientations of Mo-S bond topologies. An increase in axial tensile strain leads to a progressive decrease in the band gap for both armchair and zigzag nanotubes. For armchair nanotube, however, there is a semiconductor-to-metal transition at the tensile strain of about 8%. For both armchair and zigzag nanotubes, the effective mass of a hole is uniformly larger than its electron counterpart, and is more sensitive to strain. Based on deformation potential theory, we have calculated the carrier mobilities of MoS₂ nanotubes. It is found that the hole mobility is higher than its electron counterpart for armchair (6, 6) nanotube while the electron mobility is higher than its hole counterpart for zigzag (10, 0) nanotube. Our results highlight the tunable electronic properties of MoS₂ nanotubes, promising for interesting applications in nanodevices, such as opto-electronics, photoluminescence, electronic switch and nanoscale strain sensor.