Cathodoluminescence and Raman research of V-shape inverted pyramid in HVPE grown GaN film
Cathodoluminescence and Raman research of V-shape inverted pyramid in HVPE grown GaN film
复制标题
DOI：
10.1016/j.matlet.2006.12.065
复制
发表时间：
2007-07
影响因子：
3
通讯作者：
Tiefeng Wei;P. Ma;R. Duan;Junhong Wang;Jiewen Li;Zh. Liu;Y. Zeng
中科院分区：
文献类型：
--
作者：
Tiefeng Wei;P. Ma;R. Duan;Junhong Wang;Jiewen Li;Zh. Liu;Y. Zeng
利用自制的垂直式HVPE反应器在（0001）蓝宝石衬底上生长了高质量的GaN厚膜。薄膜表面出现了大小为100 μ m的六角倒金字塔形凹坑，凹坑由六个{10-11}三角形面组成。这些{10-11}面显示出强的发光发射，并且是掺杂的n型材料的特征。宽红光发射在{10-11}面受到抑制，仅在坑外的平坦区域发现，这与{10-11}面上的缺陷减少有关。在V形凹坑的顶点处观察到低的CL发射强度，这是由于增强的非辐射复合。拉曼光谱表明，与坑外的平坦区域相比，坑内有较高的载流子浓度和较低的应变。应变弛豫可能是GaN薄膜表面V形凹坑形成的主要机制。
Thick GaN films with high quality have been grown on (0001) sapphire substrate in a home-made vertical HVPE reactor. Micron-size hexagonal pits with inverted pyramid shape appear on the film surface, which have six triangular {10–11} facets. These {10–11} facets show strong luminescence emission and are characteristic of doped n-type materials. Broad red emission is suppressed in {10–11} facets and is only found at the flat region out of the pit, which is related with the decreasing defects on {10–11} facets. Low CL emission intensity is observed at the apex of V-shape pits due to the enhanced nonradiative recombination. Raman spectra show that there are higher carrier concentration and low strain in the pit in comparison to the flat region out of the pit. The strain relaxation may be the main mechanism of the V-shape pits formation on the GaN film surface.