Fig. 4: Dependence of exciton resonance energy on THz pump-optical probe (TPOP) time delay and THz field strength for a device with 3 L MoS2 from the production batch α.
From: Terahertz field effect in a two-dimensional semiconductor
a, b Dependence of the A-exciton resonance energy \({E}_{{{\rm{A}}}}\) and B-exciton resonance energy \({E}_{{{\rm{B}}}}\) on the TPOP time delay. \(\Delta {E}_{{{\rm{A}}}}\) and \(\Delta {E}_{{{\rm{B}}}}\) on the right axis are the shifts in the exciton resonance energies in the absence of the THz pump. Horizontal dashed lines show the resonance positions without the presence of the THz field. c Incident THz field \({F}_{x,{{\rm{in}}}}\) in this measurement. Labels (1)-(3) indicate the timing corresponding to the schematic Figs. (1)–(3) in (f). d, e Dependence of the resonance energy for A- and B-excitons on the THz field strength. This dependence was established via the time correlation between the time-dependent resonance energies in (a, b) and the time-dependent instantaneous THz field in (c). This time correlation is illustrated via color coding in (c, d, and e). Error bars in (a, b, d, and e) show the standard deviation of the exciton resonance energies as resulting from the corresponding fits. f Illustration of a quantum-confined Stark effect in a 2D semiconductor induced by an out-of-plane THz field \({F}_{z}\) under the presence of a built-in field \({F}_{z,{{\rm{bi}}}}\). Sub-Figs. (1)–(3) correspond to the timing labels (1)–(3) in (c). The solid lines illustrate the quantum-confinement potential, the dashed lines depict the energy levels of the electron and hole, and the areas filled with orange and blue colors depict the squared wave functions of the electron and hole, respectively.
