Nanowire photonic crystal (PhC) structure is one of promising approaches to enhance vertical light extraction efficiency (LEE) of ultraviolet light emitting diodes (UV LEDs). There are lots of investigations to study the structure of nanowire UV LEDs by using the finite-difference time-domain (FDTD) method. The optimal LEE are obtained by using some optimization algorithms. However, it needs a broad window, not the best values of geometrical parameters of nanowires in practical fabrication. In this paper, the vertical LEE of UV LEDs are theoretically enhanced by selecting the band gaps of AlGaN-based nanowire PhC structure. It illustrates that all the gaps can inhibit the horizontal propagation of light. However, the inhibiting ability of Gap 1 are weaker than them of Gap 2 and Gap 3. The reason is that the radii of nanowires in Gap 1 are too small to support enough guided modes. As a comparison, both Gap 2 and Gap 3 can efficiently inhibit the radiated mode propagation, and finally enhance the vertical LEE. In addition, the variations of height, number, and refractive index of nanowires on vertical LEE and optical band gaps are discussed. This work has benefits for the practical production of nanowire PhC UV LEDs.

中文翻译：

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通过选择带隙理论上提高AlGaN基纳米线光子晶体紫外发光二极管的垂直光提取效率


纳米线光子晶体（PhC）结构是提高紫外发光二极管（UV LED）垂直光提取效率（LEE）的有前途的方法之一。使用时域有限差分 (FDTD) 方法研究纳米线 UV LED 的结构有很多研究。最佳LEE是通过使用一些优化算法获得的。然而，它需要一个宽阔的窗口，而不是实际制造中纳米线几何参数的最佳值。在本文中，理论上通过选择基于AlGaN的纳米线PhC结构的带隙来增强UV LED的垂直LEE。这说明所有的间隙都会抑制光的水平传播。然而，间隙1的抑制能力弱于间隙2和间隙3。原因是间隙1中的纳米线半径太小，无法支持足够的导模。相比之下，间隙2和间隙3都能有效抑制辐射模传播，最终增强垂直LEE。此外，还讨论了纳米线在垂直 LEE 和光学带隙上的高度、数量和折射率的变化。这项工作有利于纳米线 PhC UV LED 的实际生产。