School of Science, Chang'an University, Xi'an 710061, China.
School of Physics, Northwest University, Xi'an 710069, China.
Molecules. 2023 Jul 7;28(13):5262. doi: 10.3390/molecules28135262.
Benefiting from a high quantum efficiency, low thermal emittance, and large absorption coefficient, InGaAs is an excellent group III-V compound for negative electron affinity (NEA) photocathodes. As the emission layer, InGaAs, where x = 0.15, has the optimal performance for detection in the near-infrared (NIR) region. Herein, an NEA InGaAs photocathode with AlGaAs as the buffer layer is designed in the form of a transmission mode module. The electronic band structures and optical properties of InGaAs and AlGaAs are calculated based on density functional theory. The time response characteristics of the InGaAs photocathode have been fully investigated by changing the photoelectron diffusion coefficient, the interface recombination velocity, and the thickness of the emission layer. Our results demonstrate that the response time of the InGaAs photocathode can be reduced to 6.1 ps with an incident wavelength of 1064 nm. The quantum efficiency of the InGaAs photocathode is simulated by taking into account multilayer optical thin film theory. The results indicate that a high quantum efficiency can be obtained by parameter optimization of the emission layer. This paper provides significant theoretical support for the applications of semiconductor photocathodes in the near-infrared region, especially for the study of ultrafast responses in the photoemission process.
得益于高量子效率、低热发射率和大吸收系数，InGaAs 是一种用于负电子亲和势（NEA）光电阴极的优秀 III-V 族化合物。作为发射层，x = 0.15 的 InGaAs 在近红外（NIR）区域检测方面具有最佳性能。在此，设计了一种以传输模式模块形式存在的具有 AlGaAs 作为缓冲层的 NEA InGaAs 光电阴极。基于密度泛函理论计算了 InGaAs 和 AlGaAs 的电子能带结构和光学性质。通过改变光电子扩散系数、界面复合速度和发射层厚度，充分研究了 InGaAs 光电阴极的时间响应特性。我们的结果表明，对于 1064nm 的入射波长，InGaAs 光电阴极的响应时间可以降低到 6.1ps。通过考虑多层光学薄膜理论对 InGaAs 光电阴极的量子效率进行了模拟。结果表明，通过对发射层的参数优化可以获得高量子效率。本文为半导体光电阴极在近红外区域的应用提供了重要的理论支持，特别是对光发射过程中超快响应的研究。
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