Fig. 5: Shift of exciton resonance energy in different devices and with different gating-field polarizations.

a Illustration of gating field inversion by rotating the antenna by \(180^\circ\) in the incident THz beam. The curved and straight red arrows represents the incident and gating THz field, respectively. Dependence of the A-exciton resonance energy \({E}_{{{\rm{A}}}}\) (b, d, f) and B-exciton resonance energy \({E}_{{{\rm{B}}}}\) (c, e, g) on the strength of the incident THz field \({F}_{x,{{\rm{in}}}}\), for several tested devices: b, c – device I, the antenna with 3 L MoS₂ from production batch α, d, e—device II, the antenna with 3 L MoS₂ from production batch β, f, g device III, the antenna with 4 L MoS₂ from production batch α. These measurements included inversion of the gating field by rotation of antenna by \(180^\circ\), as depicted in (a) and shown by the trace legends. Error bars in (b–g) show the standard deviation of the exciton resonance energies resulting from the corresponding fitting. Solid lines in (b, d, f): fit of the parabolic part of the dependence of A-exciton resonance energy on the incident THz field \({F}_{x,{{\rm{in}}}}\) with a quadratic equation describing the perturbative-regime quadratic quantum confined Stark effect, and the polarizability of the A-exciton established in ref. ²². These fits allow one to estimate the strength of the built-in field in the tested devices, as well as the THz field enhancement factors of the antennas and the peak THz gating field strength.