Department of Materials Science and Engineering, National Chung Hsing University, Taichung, 402, Taiwan.
Department of Photonics, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung, 40724, Taiwan.
Sci Rep. 2017 Jul 10;7(1):4968. doi: 10.1038/s41598-017-05391-0.
A GaN/AlGaN ultraviolet light emitting diode (UV-LED) structure with a porous AlGaN reflector structure has been demonstrated. Inside the UV-LED, the n-AlGaN/undoped-AlGaN stack structure was transformed into a porous-AlGaN/undoped-AlGaN stack structure through a doping-selective electrochemical etching process. The reflectivity of the porous AlGaN reflector was 93% at 374 nm with a stop-bandwidth of 35 nm. In an angle-dependent reflectance measurement, the central wavelength of the porous AlGaN reflector had blueshift phenomenon by increasing light-incident angle from 10° to 50°. A cut-off wavelength was observed at 349 nm due to the material absorption of the porous-AlGaN/u-AlGaN stack structure. In the treated UV-LED structure, the photoluminescence emission wavelength was measured at 362 nm with a 106° divergent angle covered by the porous-AlGaN reflector. The light output power of the treated UV-LED structure was higher than that of the non-treated UV-LED structure due to the high light reflectance on the embedded porous AlGaN reflector.
已经展示了一种具有多孔 AlGaN 反射器结构的 GaN/AlGaN 紫外发光二极管 (UV-LED) 结构。在 UV-LED 内部，通过掺杂选择性电化学刻蚀工艺，将 n-AlGaN/未掺杂-AlGaN 叠层结构转变为多孔-AlGaN/未掺杂-AlGaN 叠层结构。多孔 AlGaN 反射器的反射率在 374nm 时为 93%，截止带宽为 35nm。在角度相关反射率测量中，随着光入射角从 10°增加到 50°，多孔 AlGaN 反射器的中心波长出现蓝移现象。由于多孔-AlGaN/u-AlGaN 叠层结构的材料吸收，在 349nm 处观察到截止波长。在处理后的 UV-LED 结构中，在多孔 AlGaN 反射器覆盖的 106°发散角下，光致发光发射波长测量为 362nm。由于嵌入的多孔 AlGaN 反射器具有高反射率，处理后的 UV-LED 结构的光输出功率高于未经处理的 UV-LED 结构。
