Fig. 4: Electrical control of excitonic quantum interference involving the p-like high-lying trion in monolayer WSe2.
From: High-lying valley-polarized trions in 2D semiconductors
a Excitation-energy dependence of SHG spectra at gate voltages of 0, 0.5, 1.5, and 2.5 V, measured under excitation by a laser of 80 fs pulse length. b Illustration of an excitonic three-level system based on neutral and charged species. The neutral three-level system is formed by the band-edge A exciton and the p-like HX. A negatively charged three-level system is formed by the band-edge trion and the charged p-like HX. c Gate-voltage dependence of the SHG spectrum measured at an excitation energy of 1.7 eV. d SHG spectra at gate voltages of 2.4, 0, and −2.4 V. Black arrows mark the SHG dips. The gray line presents the same spectrum at 0 V (blue line) multiplied by 10 at the corresponding energy range, showing the UPL of the s-like HX. All measurements were performed at 5 K.
