AFM and SEM Study on Crystallographic and Topographical Evolution of Wet-Etched Patterned Sapphire Substrates (PSS) I. Cone-Shaped PSS Etched in Sulfuric Acid and Phosphoric Acid Mixture (3:1) at 230 degrees C
AFM and SEM Study on Crystallographic and Topographical Evolution of Wet-Etched Patterned Sapphire Substrates (PSS) I. Cone-Shaped PSS Etched in Sulfuric Acid and Phosphoric Acid Mixture (3:1) at 230 degrees C
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AFM 和 SEM 研究湿法蚀刻图案化蓝宝石基板 (PSS) 的晶体学和形貌演化 I. 在 230 ℃ 硫酸和磷酸混合物 (3:1) 中蚀刻的锥形 PSS
DOI：
10.1149/2.0221701jss
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发表时间：
2017
影响因子：
2.2
通讯作者：
Gan Yang
中科院分区：
文献类型：
--
作者：
Shen Jian;Zhang Dan;Wang You;Gan Yang
深入了解湿法刻蚀图案化蓝宝石衬底（PSS）的晶体学和形貌演化对于揭示刻蚀机理和制备优化的PSS以增强GaN基LED器件的性能至关重要。作为本论文的第一部分，我们利用互补扫描电子显微镜（SEM）和原子力显微镜（AFM），系统地研究了在230 ℃条件下，用普通腐蚀剂（H2SO 4：H3 PO 4= 3：1，体积比）对锥形PSS进行的晶体学和形貌演化。发现图案的形貌从正常的圆锥体到截头圆锥体，到具有多个暴露的晶面家族的三棱锥，然后到具有单个平面家族的六棱锥和三棱锥。三个主要暴露晶面的米勒指数随倾斜角的减小分别为{1 0 5}、{4 1 38}和{1 0 12}，其中后两个晶面为首次报道。这清楚地表明，AFM，由于其3D形貌成像能力相比，扫描电镜和聚焦离子束，可以是一个不可或缺的工具，快速和可靠的表征常规PSS样品。
A thorough understanding about the crystallographic and topographical evolution of wet-etched patterned sapphire substrates (PSS) is essential for revealing the etching mechanism and critical for fabricating optimized PSS for enhanced performance of GaN-based LED devices. As the first one of a series of three papers, using complementary scanning electron microscope (SEM) and atomic force microscope (AFM), we carried out a systematic study on the crystallographic and topographical evolution of cone-shaped PSS etched with an ordinary etchant (H 2 SO 4: H 3 PO 4= 3: 1 at volume ratio, 230 C) which enables crystallographic specific etching. The topography of patterns was found to evolve from normal cones to truncated cones, to triangular pyramids with multiple families of exposed crystallographic planes, then to hexagonal and triangular pyramids with a single family of planes. The Miller indexes of three major exposed crystallographic planes, with decreasing slant angles, were determined to be {1 0 5},{4 1 38} and {1 0 12} with the last two being reported for the first time to our best knowledge. It was clearly demonstrated that AFM, thanks to its 3D topography imaging capability compared to SEM and focused ion beam, can be an indispensable tool for fast and reliable characterization of routine PSS samples.