Abstract Silicon-cap annealing (SiCA) emerged as a promising silicidation-less ohmic contact formation method that can solve the crucial reliability limitation of ohmic contacts formed with metals; this limitation was due to carbon aggregation introduced during silicidation annealing. However, no previous study for a complete understanding of SiCA effects on the metal/SiC exists. In this study, the band-energy state of silicidation-less ohmic contacts formed by SiCA-SiC is directly estimated using hard X-ray photoelectron spectroscopy (HAXPES). The results show that Si-dot formation on the SiC surface reduces the contacts resistivity, and ohmic contact behavior is still observed even after Si-dot removal. A peak position analysis of Si 1 s orbit using HAXPES shows a clear increase in the band energy under various SiC surface conditions. Particularly, the Al/SiCA-SiC sample shows a peak shift of 0.765 eV. This strong potential barrier lowering the derived formation of the thin-depletion layer and low potential barrier on Al/SiCA-SiC junction. Moreover, the observations made using HAXPES, and transmission electron microscopy, suggest that the modification of the outer-most surface layer plays an essential role in the ohmic contact formation. These results provide insights on the ohmic contact formation mechanism for wide-band-gap semiconductor materials.

中文翻译：

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使用硬 X 射线光电子能谱估算硅帽退火 4H-SiC 表面的能带能量

摘要 硅帽退火（SiCA）是一种很有前途的无硅化欧姆接触形成方法，可以解决金属形成欧姆接触的关键可靠性限制；这种限制是由于在硅化退火过程中引入的碳聚集。然而，之前没有关于 SiCA 对金属/SiC 影响的完整理解的研究。在这项研究中，使用硬 X 射线光电子能谱 (HAXPES) 直接估计了由 SiCA-SiC 形成的无硅化欧姆接触的带能状态。结果表明，在 SiC 表面形成 Si 点降低了接触电阻率，即使在去除 Si 点后仍观察到欧姆接触行为。使用 HAXPES 对 Si 1 s 轨道的峰值位置分析显示，在各种 SiC 表面条件下，能带能量明显增加。特别是，Al/SiCA-SiC 样品显示出 0.765 eV 的峰位移。这种强大的势垒降低了 Al/SiCA-SiC 结上薄耗尽层和低势垒的衍生形成。此外，使用 HAXPES 和透射电子显微镜进行的观察表明，最外表面层的改性在欧姆接触形成中起着至关重要的作用。这些结果为宽带隙半导体材料的欧姆接触形成机制提供了见解。表明最外表面层的改性在欧姆接触形成中起着重要作用。这些结果为宽带隙半导体材料的欧姆接触形成机制提供了见解。表明最外表面层的改性在欧姆接触形成中起着重要作用。这些结果为宽带隙半导体材料的欧姆接触形成机制提供了见解。