Hexagonal boron nitride (h-BN), in particular, multilayer h-BN, has played an important role in the research of two-dimensional materials by enabling the observation of their intrinsic and excellent physical properties via effective screening of the influences from the surrounding environment. However, it is still difficult to synthesize high-quality multilayer h-BN in large scale, and its growth mechanism is not clearly understood. Here, we investigated the chemical vapor deposition (CVD) growth of multilayer h-BN using thin Ni–Fe films that are deposited on sapphire substrates with different crystal planes. The Ni–Fe film on r-plane sapphire was found to produce a uniform multilayer h-BN sheet whose surface coverage is much higher than those on c- and a-plane sapphire. Electron backscatter diffraction and X-ray diffraction investigations revealed that the uniform segregation of multilayer h-BN on Ni–Fe/r-sapphire occurs simultaneously with a drastic structural change of the Ni–Fe thin film from polycrystalline to face-centered cubic (fcc (111)) structure. On the other hand, the Ni–Fe films on c- and a-plane sapphire possessed the fcc (111) structure even before the reaction with borazine feedstock and did not show such structural change. The unique crystallographic change of the Ni–Fe thin film associated with uniform h-BN segregation was further supported by the studies using spinel substrates. Our work indicates the essential role of dynamic evolution of the crystal structure of the thin-film metal catalyst in h-BN growth, highlighting the importance of the controlling crystallographic properties of the metal catalyst for the synthesis of high-quality and uniform multilayer h-BN films.

中文翻译：

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金属薄膜的结构转变驱动均匀的多层六方氮化硼化学气相沉积生长

六方氮化硼（h-BN），尤其是多层h-BN，在二维材料的研究中发挥了重要作用，它可以通过有效地筛选周围环境的影响来观察其固有和优异的物理性能环境。然而，仍然难以大规模合成高质量的多层h-BN，并且其生长机理还不清楚。在这里，我们使用沉积在具有不同晶面的蓝宝石衬底上的镍铁薄膜来研究了多层h-BN的化学气相沉积（CVD）生长。在Ni-Fe膜- [R -平面蓝宝石被发现产生均匀的多层的h-BN片的表面覆盖率比那些高得多的Ç -和一个平面蓝宝石。电子背散射衍射和X射线衍射研究表明，多层h-BN在Ni-Fe / r-蓝宝石上均匀偏析的发生与Ni-Fe薄膜从多晶到面心立方（fcc （111））结构。另一方面，镍铁薄膜在c-和a平面蓝宝石甚至在与硼嗪原料反应之前就具有fcc（111）结构，并且没有显示出这种结构变化。使用尖晶石衬底的研究进一步支持了与均匀h-BN偏析相关的Ni-Fe薄膜的独特晶体学变化。我们的工作表明了薄膜金属催化剂晶体结构的动态演变在h-BN生长中的重要作用，突出了控制金属催化剂的晶体学性质对于合成高质量且均匀的多层h-b的重要性。 BN电影。