Strong coupling between a topological insulator and a III-V heterostructure at terahertz frequency

作者：D. Quang To, Zhengtianye Wang, Dai Q. Ho, Ruiqi Hu, Wilder Acuna, Yongchen Liu, Garnett W. Bryant, Anderson Janotti, Joshua M. O. Zide, Stephanie Law, Matthew F. Doty · 发表于：Physical Review Materials · 年份：2022 · DOI：10.1103/physrevmaterials.6.035201 · 被引用次数：11 · 研究领域：Topological Materials and Phenomena、Strong Light-Matter Interactions、Thermal Radiation and Cooling Technologies

We theoretically probe the emergence of strong coupling in a system consisting of a topological insulator (TI) and a III-V heterostructure using a numerical approach based on the scattering matrix formalism. Specifically, we investigate the interactions between terahertz excitations in a structure composed of ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ and GaAs materials. We find that the interaction between the ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ layer and AlGaAs/GaAs quantum wells with intersubband transitions (ISBTs) in the terahertz frequency regime creates new hybrid modes, namely Dirac plasmon-phonon-ISBT polaritons. The formation of these hybrid modes results in anticrossings (spectral mode splitting) whose magnitude is an indication of the strength of the coupling. By varying the structural parameters of the constituent materials, our numerical calculations reveal that the magnitude of splitting depends strongly on the doping level and the scattering rate in the AlGaAs/GaAs quantum wells, as well as on the thickness of the GaAs spacer layer that separates the quantum-well structure from the TI layer. Our results reveal the material and device parameters required to obtain experimentally observable signatures of strong coupling. Our model includes the contribution of an extra two-dimensional hole gas (2DHG) that is predicted to arise at the ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$/GaAs interface, based on density functional theory (DFT) calculations that explicitly account for d...