Quantum Hall Effect of Electrons and Holes in 2D Te

Bilayer electron/hole systems provide a rich platform for exploring complex transport phenomena. In this study, we experimentally investigated the quantum Hall effect of both electrons and holes in 2D Tellurium (Te). Due to its narrow band gap and ultrathin nature, the carrier type and density in 2D Te can be tuned by applying gate voltages within the same device. The Landau level spectrum differs between the conduction and valence bands, thanks to Te's unique chiral crystal structure and strong spin-orbit interaction. This makes 2D Te an excellent material for studying the quantum Hall effect with various degrees of freedom, including spin, valley, and layer. Using gate spectroscopy techniques, we measured the Landau level spectrum by adjusting the magnetic field and both the top and back gate voltages. Bilayer quantum Hall states were observed in electron-electron, hole-hole, and electron-hole regions. Additionally, we observed Landau level crossings between electrons and holes, as well as the evolution of the zeroth quantum Hall plateau.