分析纳米结构光电导器件的高效间断Galerkin格式
Efficient Discontinuous Galerkin Scheme for Analyzing Nanostructured Photoconductive Devices
摘要：
在光电导器件（PCD）的设计中引入等离子体纳米结构显著提高了它们的光-太赫兹转换效率。然而，这种改进是以增加这些设备的设计和仿真的复杂性为代价的。事实上，由于时间和空间上的多个特征尺度导致的高计算成本，纳米结构PCD的多物理场过程和复杂器件几何形状的准确和有效建模是具有挑战性的。在这项工作中，一个不连续的伽辽金（DG）为基础的单位细胞计划，有效地模拟与周期性纳米结构的PCD。该计划考虑了两个物理阶段的设备和模型，他们使用两个耦合系统：一个系统的泊松和漂移扩散方程描述的非平衡稳态，和一个系统的麦克斯韦和漂移扩散方程描述的瞬态阶段。在单位单元的相对边界上强制执行“电位降”边界条件以模拟偏置电压的效果。周期性边界条件用于载流子密度和电磁场。用DG方法对耦合方程和边界条件描述的单胞模型进行离散。数值结果表明，所提出的DG基单胞方案在预测THz光电流方面与考虑整个器件的DG框架具有相同的精度，同时显著降低了计算成本。
英文摘要：
Incorporation of plasmonic nanostructures in the design of photoconductive devices (PCDs) has significantly improved their optical-to-terahertz conversion efficiency. However, this improvement comes at the cost of increased complexity for the design and simulation of these devices. Indeed, accurate and efficient modeling of multiphysics processes and intricate device geometries of nanostructured PCDs is challenging due to the high computational cost resulting from multiple characteristic scales in time and space. In this work, a discontinuous Galerkin (DG)-based unit-cell scheme for efficient simulation of PCDs with periodic nanostructures is proposed. The scheme considers two physical stages of the device and models them using two coupled systems: a system of Poisson and drift-diffusion equations describing the nonequilibrium steady state, and a system of Maxwell and drift-diffusion equations describing the transient stage. A "potential-drop" boundary condition is enforced on the opposing boundaries of the unit cell to mimic the effect of the bias voltage. Periodic boundary conditions are used for carrier densities and electromagnetic fields. The unit-cell model described by these coupled equations and boundary conditions is discretized using DG methods. Numerical results demonstrate that the proposed DG-based unit-cell scheme has the same accuracy in predicting the THz photocurrent as the DG framework that takes into account the whole device, while it significantly reduces the computational cost.
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