School of Electrical and Electronic Engineering and ‡Temasek Laboratories@NTU, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.
Nano Lett. 2014 Feb 12;14(2):839-46. doi: 10.1021/nl404207f. Epub 2014 Jan 23.
Hexagonal-boron nitride (h-BN) or "white graphene" has many outstanding properties including high thermal conductivity, high mechanical strength, chemical inertness, and high electrical resistance, which open up a wide range of applications such as thermal interface material, protective coatings, and dielectric in nanoelectronics that easily exceed the current advertised benefits pertaining to the graphene-based applications. The development of h-BN films using chemical vapor deposition (CVD) has thus far led into nucleation of triangular or asymmetric diamond shapes on different metallic surfaces. Additionally, the average size of the triangular domains has remained relatively small (∼ 0.5 μm(2)) leading to a large number of grain boundaries and defects. While the morphology of Cu surfaces for CVD-grown graphene may have impacts on the nucleation density, domain sizes, thickness, and uniformity, the effects of the decreased roughness of Cu surface to develop h-BN films are unknown. Here, we report the growth and characterization of novel large area h-BN hexagons using highly electropolished Cu substrate under atmospheric pressure CVD conditions. We found that the nucleation density of h-BN is significantly reduced while domain sizes increase. In this study, the largest hexagonal-shape h-BN domain observed is 35 μm(2), which is an order of magnitude larger than a typical triangular domain. As the domains coalesce to form a continuous film, the larger grain size offers a more pristine and smoother film with lesser grain boundaries induced defects.
六方氮化硼（h-BN）或“白石墨烯”具有许多优异的性质，包括高热导率、高强度、化学惰性和高电阻，这为热界面材料、防护涂层和纳米电子学中的介电材料等领域的应用开辟了广阔的前景，这些应用很容易超过目前与基于石墨烯的应用相关的广告效益。迄今为止，使用化学气相沉积（CVD）开发 h-BN 薄膜导致在不同金属表面上形成三角形或不对称的金刚石形状的成核。此外，三角形畴的平均尺寸仍然相对较小（约 0.5 μm²），导致大量晶界和缺陷。虽然 CVD 生长石墨烯的 Cu 表面的形态可能会影响成核密度、畴尺寸、厚度和均匀性，但 Cu 表面粗糙度降低对开发 h-BN 薄膜的影响尚不清楚。在这里，我们报告了在常压 CVD 条件下使用高度电解抛光的 Cu 衬底生长和表征新型大面积 h-BN 六边形的情况。我们发现 h-BN 的成核密度显著降低，而畴尺寸增加。在这项研究中，观察到的最大六边形 h-BN 畴尺寸为 35 μm²，比典型的三角形畴大一个数量级。随着畴的合并形成连续的薄膜，较大的晶粒尺寸提供了更原始、更光滑的薄膜，具有较少的晶界诱导缺陷。
