利用纳米孔（柱）阵列同时提高LED内、外量子效率的研究

LED因其诸多优点已经被广泛应用于照明、交通、背光源、全彩显示屏等许多领域。因此，探讨表面界面结构、微纳结构对LED发光效率的影响规律，具有重要的理论价值和现实意义。本项目拟采用干法刻蚀工艺，从InGaN/GaN多量子阱基蓝绿光LED表面自上而下刻蚀、形成具有周期性排列的纳米孔（或柱）阵列结构；研究、分析不同刻蚀工艺（如FIB、ICP）、结构参数（如孔或柱的深度、直径、密度及形状）和后续处理工艺（如退火、钝化）对LED发光效率的影响规律。特别关注将纳米孔（柱）的深度分别扩展至p-GaN层、有源区及n-GaN层时，对LED发光效率的影响规律和作用机制。根据上述实验结果，选取合适的制备工艺和结构参数，来达到既能降低LED的应力和缺陷以提高内量子效率、同时又能有效降低LED表面对出射光的内反射（即增强光的提取效率）以提高外量子效率的目的，从而探索出制备高效稳定LED器件的新工艺、新结构和新原理。

LED structures have been widely used in many areas of lighting, traffic, backlight, full-color display and so on because of their many advantages. Therefore, exploring the effect of the surface- and interface-structure as well as the micro- and nano-structure on LED PL efficiency has important theoretical and practical significance. In this project, a nanohole (or nanorod) array structure with a spatial periodicity will be formed from the top surface of the LED toward the n-typed GaN layer by dry etching; The effects of the nanohole (or nanorod) array structures formed by different etching processes (such as FIB, ICP), structural parameters (depth, diameter, density and shape of the nanohole or nanorod) and subsequent treatment processes (annealing, passivation) on the LED PL efficiency are investigated. Particularly notice the effects of nanohole (nanorod) depth parameter on LED PL efficiency when the depth varies from the p-type layer to active region and to n-type layer. Based on the experimental results mentioned above, select the appropriate fabrication process and structural parameter to achieve the enhancements both in the internal quantum efficiency by decreasing the stresses and defects within LED, and in the external quantum efficiency (i.e. enhancing light extraction efficiency) by reducing the internal reflection of the emitted light caused by LED surface, and finally obtain a new technology, new structure and new principle for fabricating the high efficient and stable LED devices.