Fig. 3: High-lying excitons and trions in monolayer MoSe₂.

a Doping dependence of band-edge excitons (X) from monolayer MoSe₂, measured by the PL as a function of the gate voltage applied to a top graphite electrode. b UPL as a function of gate voltage. The excitation is at 1.654 eV in resonance with X. The features attributed to the neutral HX, and the negatively and positively charged HX are marked as HX₀, HX⁻, and HX⁺, respectively. c A rescaled plot of panel B highlighting the HX emission. d–f Polarization resolved UPL spectra at gate voltages of 2 V (d), 0 V (e), and −2 V (f). g Illustration of resonant pumping scheme of the A exciton in the +K valley with a σ⁺ circularly polarized CW laser. The inset illustrates the Auger-like exciton-exciton annihilation process. h Schematic of the dominant negatively charged high-lying trion at the +K valley, with σ⁻ polarized emission. i Schematic of the dominant positively charged high-lying trion at the +K valley, with σ⁻ polarized emission.