Twisted Transition metal dichalcogenide (TMDC) structures exhibit moiré superlattice structures, which bring interesting properties and open new avenues for exploring fundamental physical phenomena. Due to the strong Coulomb interaction originating from 2D structure, excitonic states can be used to study the properties of TMDC materials. Photoluminescence (PL) spectroscopy is a useful method to investigate the optical emission information from excitonic states.

In this study, we fabricated a twist bilayer WSe₂ device with a twist angle of 1.1° and observed intralayer and interlayer excitonic emission signals in PL measurement. We found the quenching of the intralayer signal and the enhancement of the interlayer signal in the twist bilayer region compared to the monolayer region with th...[ Read more ]

Twisted Transition metal dichalcogenide (TMDC) structures exhibit moiré superlattice structures, which bring interesting properties and open new avenues for exploring fundamental physical phenomena. Due to the strong Coulomb interaction originating from 2D structure, excitonic states can be used to study the properties of TMDC materials. Photoluminescence (PL) spectroscopy is a useful method to investigate the optical emission information from excitonic states.

In this study, we fabricated a twist bilayer WSe₂ device with a twist angle of 1.1° and observed intralayer and interlayer excitonic emission signals in PL measurement. We found the quenching of the intralayer signal and the enhancement of the interlayer signal in the twist bilayer region compared to the monolayer region with the extra splitting of peaks for both intralayer and interlayer signal in the twist bilayer region.

By using excitation power, helicity, and magnetic field dependent PL, we further investigated the characteristics of split peaks. For intralayer excitonic signal, we found similar power factor for all split peaks except one peak showed fast increase with excitation power qualitatively. When the device is excited with linearly polarized light, the intensity of split peaks under σ+ detection is significantly larger than that under σ- detection under a magnetic field with direction from the bottom to the top of the device. The peaks further split under magnetic fields and shifted to different directions for σ+ and σ- detection. The g-factor ranging from 6-10 for intralayer peaks was obtained except one peak had the opposite sign. For interlayer excitonic signal, larger g factors were estimated.