Optical absorption in the terahertz region in HgTe/HgCd(Mn)Te double quantum well structures with a topological phase and structural inversion asymmetry

摘要

On the basis of the eight-band kp model, the theoretical engineering of HgTe/HgCd(Mn)Te double quantum well (DQW) structures is presented in this study. An external magnetic field and structural inversion asymmetry are taken into account. The advantages of HgTe two-dimensional topological insulator (2D TI) layers with x-Cd or x-Mn over pure 2D TI HgTe films are theoretically and experimentally proven. All advantages, such as the larger Fermi velocity, very high mobility of the surfaces states, the larger g factor for such mixed layers together with the sharpens on the edge layers in the 2D TI structures and the structural inversion asymmetry (which can be easy realized in the 2D DQW case), mean that the presented structures are encouraging as the basis of, for example, high resolution terahertz detectors. Considering this possible application, the optical transition for the cyclotron resonance and the excitation transfer in the terahertz region is analyzed. The results of the presented investigation are very promising for the application of HgTe/HgCd(Mn)Te DQW structures in terahertz detector.