Quantum Transport in n-type Tellurium Quantum Well

Tellurium (Te) is a narrow bandgap semiconductor with a unique chiral crystal structure. Quantum transport on n-type two-dimensional (2D) Te, realized by the atomic layer deposition doping technique, reveals its topological nature with Berry phase in the conduction band. In this work, we fabricated double-gated n-type Te Hall–bar devices, which can operate as two separate or coupled top and bottom layers controlled by the top gate and back gate independently. Profound Shubnikov-de Haas (SdH) oscillations are observed in both top and bottom layers. Temperature and density dependence of Landau levels of both layers are measured and analyzed. For example, under high magnetic field of 31T, we can identify two composite states such as ν=6 or 8, which are made of two quantum Hall states ν^b=4 from the bottom layer and ν^t=2 or 4 from the top layer.