AlGaN is the material of choice for high-efficiency deep UV light sources, which is the only alternative technology to replace mercury lamps for water purification and disinfection. At present, however, AlGaN-based mid- and deep UV LEDs exhibit very low efficiency. Here, we report a detailed investigation of the epitaxy and characterization of LEDs utilizing an AlGaN/GaN/AlGaN tunnel junction structure, operating at ∼265 nm, which have the potential to break the efficiency bottleneck of deep UV photonics. A thin GaN layer was incorporated between p+ and n+-AlGaN to reduce the tunneling barrier. By optimizing the thickness of the GaN layer and thickness of the top n-AlGaN contact layer, we demonstrate AlGaN deep UV LEDs with a maximum external quantum efficiency of 11% and wall-plug efficiency of 7.6% for direct on-wafer measurement. It is also observed that the devices exhibit severe efficiency droop under low current densities, which is explained by the low hole mobility, due to the hole hopping conduction in the Mg impurity band and the resulting electron overflow.

中文翻译：

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AlGaN隧道结发光二极管的性能特点

AlGaN 是高效深紫外光源的首选材料，是替代汞灯用于水净化和消毒的唯一替代技术。然而，目前基于 AlGaN 的中深紫外 LED 的效率非常低。在这里，我们报告了使用 AlGaN/GaN/AlGaN 隧道结结构的 LED 的外延和表征的详细研究，工作波长约为 265 nm，这有可能打破深紫外光子学的效率瓶颈。在 p+ 和 n+-AlGaN 之间加入薄的 GaN 层以减少隧道势垒。通过优化 GaN 层的厚度和顶部 n-AlGaN 接触层的厚度，我们展示了 AlGaN 深紫外 LED，其最大外部量子效率为 11%，壁塞效率为 7.6%，用于直接晶圆上测量。