Boron nitride (BN) is a promising 2D material as well as a potential wide-bandgap semiconductor. Chemical vapor deposition (CVD) is commonly used to deposit single layers or thin films of BN, but the deposition process is insufficiently understood at an atomic scale. the CVD of BN is studied using two boron precursors, the organoboranes, triethylborane, and trimethylborane. Using high resolution (scanning) transmission electron microscopy and electron energy loss spectroscopy, this study shows that hexagonal-BN (h-BN) nucleates and grows epitaxially for ≈4 nm before it either polytype transforms to rhombohedral-BN (r-BN), turns to less ordered turbostratic-BN or is terminated by a layer of amorphous carbon. this study proposes that the carbon in the organoboranes deposits on the epitaxially growing h-BN surface and this either leads to the polytype transition to r-BN, the transition to less ordered BN growth, or complete surface poisoning with carbon terminating BN growth. These results question the use of organoboranes in CVD of epitaxial BN films, and the polytype stability of h-BN growing on graphene.

中文翻译：

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碳对外延六方氮化硼薄膜多型及生长稳定性的影响

氮化硼（BN）是一种有前途的二维材料，也是一种潜在的宽带隙半导体。化学气相沉积 (CVD) 通常用于沉积单层 BN 或薄膜，但在原子尺度上对沉积过程的了解还不够。使用两种硼前体（有机硼烷、三乙基硼烷和三甲基硼烷）研究了 BN 的 CVD。使用高分辨率（扫描）透射电子显微镜和电子能量损失光谱，本研究表明，六方氮化硼（h-BN）在其多型转变为菱形氮化硼（r-BN）之前成核并外延生长约 4 nm，变成有序度较低的乱层氮化硼或由一层无定形碳终止。这项研究提出，有机硼烷中的碳沉积在外延生长的 h-BN 表面上，这要么导致多型转变为 r-BN，转变为有序性较低的 BN 生长，要么导致碳终止 BN 生长的完全表面中毒。这些结果对有机硼烷在外延 BN 薄膜 CVD 中的使用以及在石墨烯上生长的 h-BN 的多型稳定性提出了质疑。