Robust Excitons and Trions in Monolayer MoTe2

Molybdenum telluride (MoTe2) has emerged as a special member in the family of two-dimensional transition metal dichalcogenide semiconductors, owing to the strong spin–orbit coupling and relatively small energy gap, which offers new applications in valleytronic and excitonic devices. Here we successfully demonstrated the electrical modulation of negatively charged (X –), neutral (X 0), and positively charged (X +) excitons in monolayer MoTe2 via photoluminescence spectroscopy. The binding energies of X + and X – were measured to be ∼24 and ∼27 meV, respectively.The exciton binding energy of monolayer MoTe2 was measured to be 0.58 ± 0.08 eV via photoluminescence excitation spectroscopy, which matches well with our calculated value of 0.64 eV.