Executive Summary : | This proposal aims to explore spin-valley locking effects on quasiparticle resonances in doped 2D semiconductors in the high carrier-density regime (larger than 10¹²/cm²). The study will use combined magneto-optical and magneto-transport methods to determine carrier density in gated monolayers of transition metal dichalcogenides (TMDCs) of the form MX₂. The project will quantitatively investigate the transfer of oscillator strength from trions to excitons in gated monolayers using μPhotoluminescence (μPL) and μAbsorption (μAbs) with carrier density. It will also detect the presence of Fermi-edge singularity (FES) in gated monolayers using temperature-resolved μAbs, μPL, and μFaraday rotation (μFR) spectroscopy in the high-carrier density regime. The Landau quantization of electron gas under high magnetic fields will be investigated using μRef and μPL spectroscopy in collaboration with the National High Magnetic Field Laboratory, Grenoble (France). The effect of carrier filling on the Landé g-factor of exciton and trion resonances will be determined using μFR, and the debate on charged quasiparticle excitations in low density regimes will be settled. The project will also study polarization characteristics of trions in doped bilayer WS₂, WSe₂, MoS₂, and MoSe₂ by performing μPL under high magnetic fields. The high-carrier density regime in 2D semiconductors is expected to open new dimensions in research, including Fermi-edge singularities, exotic magneto-optical and transport effects related to excitations of the Fermi sea, and their implications to valleytronics and quantum information. |