Abstract Triangular defects are frequently observed in 4H-SiC homoepitaxial layers and their existence is reported to greatly degrade the performance of corresponding p-n junction diodes. Regarding the formation mechanisms of these defects, there have been a few models postulated before, which will be briefly reviewed here. In this study, we have observed a significant number of triangular defects in a 150mm n - /n + commercial 4H-SiC homoepitaxial wafer using Nomarski Microscopy and Synchrotron X-ray topography (SXRT). The observed defects show varying morphology and complexity. In order to investigate their complex microstructures and gain insight on the formation mechanism, selected triangular defects were characterized by high resolution transmission electron microscopy (HRTEM) and micro-Raman spectroscopy. Results confirm that all the triangular defects have a 3C-SiC nature. In addition, { 1 1 1 } twins and double positioning boundaries (DPBs) were frequently observed inside the triangular defects. Based on these observations, a model has been developed to interpret the formation mechanism of these defects. In this model, the introduction of downfall particle during epitaxy creates a large triangular on-axis terrace, on which 3C-SiC crystals nucleate 2-dimensionally and grow under no constraint, eventually overgrown by 4H-SiC growth steps.

中文翻译：

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了解 4H-SiC 同质外延中三角形缺陷的微观结构

摘要 在 4H-SiC 同质外延层中经常观察到三角形缺陷，据报道它们的存在会大大降低相应 pn 结二极管的性能。关于这些缺陷的形成机制，之前已经提出了几个模型，这里简单回顾一下。在这项研究中，我们使用 Nomarski 显微镜和同步加速器 X 射线形貌 (SXRT) 在 150mm n - /n + 商用 4H-SiC 同质外延晶片中观察到大量三角形缺陷。观察到的缺陷显示出不同的形态和复杂性。为了研究其复杂的微观结构并深入了解其形成机制，通过高分辨率透射电子显微镜（HRTEM）和显微拉曼光谱对选定的三角形缺陷进行了表征。结果证实所有三角形缺陷都具有 3C-SiC 性质。此外，在三角形缺陷内经常观察到 { 1 1 1 } 孪晶和双定位边界 (DPB)。基于这些观察，已经开发了一个模型来解释这些缺陷的形成机制。在该模型中，外延过程中下落粒子的引入产生了一个大的三角形轴上平台，在该平台上 3C-SiC 晶体二维成核并在不受约束的情况下生长，最终通过 4H-SiC 生长步骤过度生长。