Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
Nature. 2012 Aug 30;488(7413):627-32. doi: 10.1038/nature11408.
Precise spatial control over the electrical properties of thin films is the key capability enabling the production of modern integrated circuitry. Although recent advances in chemical vapour deposition methods have enabled the large-scale production of both intrinsic and doped graphene, as well as hexagonal boron nitride (h-BN), controlled fabrication of lateral heterostructures in these truly atomically thin systems has not been achieved. Graphene/h-BN interfaces are of particular interest, because it is known that areas of different atomic compositions may coexist within continuous atomically thin films and that, with proper control, the bandgap and magnetic properties can be precisely engineered. However, previously reported approaches for controlling these interfaces have fundamental limitations and cannot be easily integrated with conventional lithography. Here we report a versatile and scalable process, which we call 'patterned regrowth', that allows for the spatially controlled synthesis of lateral junctions between electrically conductive graphene and insulating h-BN, as well as between intrinsic and substitutionally doped graphene. We demonstrate that the resulting films form mechanically continuous sheets across these heterojunctions. Conductance measurements confirm laterally insulating behaviour for h-BN regions, while the electrical behaviour of both doped and undoped graphene sheets maintain excellent properties, with low sheet resistances and high carrier mobilities. Our results represent an important step towards developing atomically thin integrated circuitry and enable the fabrication of electrically isolated active and passive elements embedded in continuous, one-atom-thick sheets, which could be manipulated and stacked to form complex devices at the ultimate thickness limit.
精确控制薄膜的电学性能是实现现代集成电路生产的关键能力。尽管化学气相沉积方法的最新进展已经能够大规模生产本征和掺杂石墨烯以及六方氮化硼（h-BN），但在这些真正原子级薄的系统中，无法实现横向异质结构的受控制造。石墨烯/h-BN 界面特别有趣，因为已知在连续原子级薄的薄膜中可能共存不同原子组成的区域，并且通过适当的控制，可以精确设计带隙和磁性。然而，以前报道的控制这些界面的方法存在根本限制，并且不能与传统光刻技术轻易集成。在这里，我们报告了一种通用且可扩展的工艺，我们称之为“图案化再生长”，它允许在导电石墨烯和绝缘 h-BN 之间以及本征和替代掺杂石墨烯之间进行空间受控的横向结合成。我们证明了这些薄膜在这些异质结上形成了机械连续的薄片。电导测量证实了 h-BN 区域的横向绝缘行为，而掺杂和未掺杂石墨烯片的电性能都保持着优异的特性，具有低的电阻和高的载流子迁移率。我们的结果代表了朝着开发原子级薄集成电路迈出的重要一步，并能够制造嵌入连续、单原子厚薄片中的电隔离有源和无源元件，这些元件可以被操纵和堆叠，以在最终厚度限制下形成复杂的设备。
