Hexagonal boron nitride (h-BN) is a critical 2D insulator used as a substrate, gate dielectric, or encapsulation layer for graphene and other 2D materials and their van der Waals heterostructures. It is also promising as an active layer in single-photon emitters and other photonic devices. With the chemical formula H₃N-BH₃, ammonia borane is the most attractive precursor for up-scalable growth of large-area h-BN, using chemical vapor deposition given its stoichiometric B:N ratio, high stability under ambient conditions, nontoxicity, and high solubility in common solvents. Here, the synthesis of large-area (100 × 150 mm²) crystalline hexagonal boron nitride layers by thermal activation and decomposition of the precursor ammonia borane is presented. We describe two different reaction pathways for h-BN synthesis, providing evidence for dissimilarities in the sublimation kinetics of ammonia borane and how these differences critically influence the growth of h-BN. This understanding helps us accelerate h-BN production, reuse precursors, and reduce machine runtime, paving the way for upscalability. Moreover, our work provides a consistent unified view explaining the diverse deposition conditions reported in the literature for h-BN grown by CVD using ammonia borane as a precursor.

中文翻译：

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氨硼烷升华动力学在均匀、大面积六方氮化硼化学气相沉积中的作用

六方氮化硼 (h-BN) 是一种关键的二维绝缘体，用作石墨烯和其他二维材料及其范德华异质结构的基板、栅极电介质或封装层。它还有望作为单光子发射器和其他光子器件中的活性层。具有化学式 H ₃ N-BH ₃，氨硼烷是大面积 h-BN 放大生长的最有吸引力的前体，由于其化学计量的 B:N 比，使用化学气相沉积，在环境条件下具有高稳定性，无毒, 在普通溶剂中溶解度高。在这里，合成大面积（100  ×  150 mm ²) 呈现了通过热活化和分解前体氨硼烷的结晶六方氮化硼层。我们描述了 h-BN 合成的两种不同反应途径，为氨硼烷升华动力学的差异以及这些差异如何严重影响 h-BN 的生长提供了证据。这种理解有助于我们加速 h-BN 生产、重复使用前体并减少机器运行时间，为升级铺平道路。此外，我们的工作提供了一致的统一观点，解释了文献中报道的使用氨硼烷作为前体通过 CVD 生长的 h-BN 的不同沉积条件。