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Electron-plasmonic devices are of strong interest for terahertz applications. In this work, we develop rigorous computational tools using finite difference time domain (FDTD) methods for accurate modeling of these devices. Existing full-wave-hydrodynamic models already combine Maxwell's and hydrodynamic electron-transport equation for multiphysical hybrid modeling. However, these multilevel methods are time-consuming as dense mesh is required for plasmonic modeling. Therefore, they are not suited for design and optimization. To address this issue, we propose new iterative ADI-FDTD-hydrodynamic hybrid coupled model. The new implementations provide time-efficient, yet accurate, modeling of these devices. It is demonstrated that for a typical simulation, up to 50% reduction in simulation-time is achieved with a nominal 3% error in calculations.Using the new tool-set, we investigate several devices that operate using the properties of 2D electron gas (2DEG). We provide one of the first multiphysical numerical analyses of these devices, giving accurate estimates of their terahertz performance. The developed tool allows simulation of arbitrary 2DEG based terahertz devices, providing useful and intuitive 2D field information. This has allowed understanding of the operation and radiation principles of these devices. Specifically, we examine the known plasma-wave instability in short-channel high electron mobility transistors (HEMTs) that leads to terahertz emissions at cryogenic temperatures. We also examine terahertz emitters that exploit resonant tunneling induced negative differential resistance (NDR) in HEMTs. Finally, using this tool we numerically demonstrate the existence of acoustic and optical-plasmonic modes within 2DEG bilayer systems in HEMTs. Methods for exciting and controlling these modes are also discussed enabling new physics among bilayer devices. |
