Shear strain bandgap tuning of monolayer MoS₂

Bandgap tuning is an attractive property of two-dimensional semiconductors and monolayer MoS2, in particular. We report here the bandgap tuning of monolayer MoS2. This was achieved by growing monolayer MoS2 on optical fibers that were then subjected to torsion, such that pure shear was transferred to MoS2. The effect of shear was inferred from the observed photoluminescence spectrum, after which a blue shift of ∼ 10 meV / % emerged. Detailed analysis revealed that this shift is mainly due to the trion luminescence and less due to the excitons. This observation experimentally uncovers the behavior of MoS2 under a yet uncharted pure shear deformation, which may enable the development of devices, such as tunable electronic components and high-precision sensors.