Self-assembled GaN nanorods were grown by metal-organic chemical vapor deposition. A highly regular rosette-shaped cathodoluminescence pattern in the GaN nanorods is observed, where its origin is helpful to deepen the understanding of GaN nanorod growth. The pattern forms at the very early stages of nanorod growth, which consists of yellow luminescence at the edges and the non-luminous region at six vertices of the hexagon. To clarify its origin, we carried out detailed cathodoluminescence studies, electron microscopy studies and nanoscale secondary ion mass spectrometry at both the nanorod surface and cross-section. We found the pattern is not related to optical resonance modes or polarity inversion, which are commonly reported in GaN nanostructures. After chemical composition and strain analysis, we found higher carbon and nitrogen cluster concentration and large compressive strain at the pattern area. The pattern formation may relate to facet preferential distribution of non-radiative recombination centers related to excess carbon/nitrogen. This work provides an insight into strain distribution and defect-related emission in GaN nanorod, which is critical for future optoelectronic applications.

通过金属有机化学气相沉积法生长自组装的GaN纳米棒。在GaN纳米棒中观察到高度规则的玫瑰状阴极发光图案，其起源有助于加深对GaN纳米棒生长的理解。该图案在纳米棒生长的非常早期阶段形成，其由边缘的黄色发光和六边形的六个顶点的非发光区域组成。为了阐明其起源，我们在纳米棒的表面和横截面均进行了详细的阴极发光研究，电子显微镜研究和纳米级二次离子质谱。我们发现该图案与GaN纳米结构中通常报道的光学共振模式或极性反转无关。经过化学成分和应变分析，我们发现图案区域的碳和氮团簇浓度较高，压缩应变较大。图案形成可以涉及与过量碳/氮有关的非辐射复合中心的方面优先分布。这项工作提供了对GaN纳米棒中应变分布和缺陷相关发射的见解，这对于未来的光电应用至关重要。