Modeling and simulation of a GaAs/AlGaAs quantum well photodetector for terahertz application
摘要
This paper presents a novel GaAs/AlGaAs-based Quantum Well Photodetector (QWP) for Terahertz (THz) detection. The photodetector is optimized to operate in the 3.9–4.6 THz frequency range, with peak performance at 4.3 THz (69.7 µm). The performance of the QWP is analyzed in terms of quantum efficiency, responsivity, dark current, and capture probability in the high-frequency terahertz region using simulation tools MATLAB and TCAD. The optimized structure corresponds to a quantum well width of Lw = 180 Å and an aluminum mole fraction of x = 0.019, yield a high responsivity of 0.31 A/W, a low dark current of 0.99 mA, and a nearly constant capture probability 0.351 in the 3.9–4.6 THz range. These optimized values lead to enhanced wavelength detection sensitivity of the device, which arises from improved carrier transport, higher electrical conductivity, and stronger photoconductive gain. The simulation results are consistent with previously reported experimental studies, confirming the validity of the proposed model. The developed QWP demonstrates promising potential for next-generation terahertz applications, including 6G wireless and satellite communication systems. A key novelty of this work lies in the optimized GaAs/AlGaAs quantum well parameters, which improve responsivity, and quantum efficiency and reduce dark current for THz detection. Notably, the capture probability's slope remains negative and decreasing with quantum well width and exhibiting a low constant value between 3.9–4.6 THz. This observation is believed to enhance the electrical conductivity of the detector and hence, its gain increases. This study presents a novel observation and is being reported for the first time. The developed model is a strong contender for high-speed free-space optical and wireless communications.