The combination of two-dimensional (2D) materials into heterostructures enables the formation of atomically thin devices with designed properties. To achieve a high-density, bottom-up integration, the growth of these 2D heterostructures via van der Waals epitaxy (vdWE) is an attractive alternative to the currently mostly employed mechanical transfer, which is problematic in terms of scaling and reproducibility. Controlling the location of the nuclei formation remains a key challenge in vdWE. Here, a focused He ion beam is used to deterministically place defects in graphene substrates, which serve as preferential nucleation sites for the growth of insulating, 2D hexagonal boron nitride (h-BN). Therewith a mask-free, selective-area vdWE (SAvdWE) is demonstrated, in which nucleation yield and crystal quality of h-BN are controlled by the ion beam parameters used for defect formation. Moreover, h-BN grown via SAvdWE is shown to exhibit electron tunneling characteristics comparable to those of mechanically transferred layers, thereby lying the foundation for a reliable, high-density array fabrication of 2D heterostructures for device integration via defect engineering in 2D substrates.

将二维 (2D) 材料结合到异质结构中，可以形成具有设计特性的原子级薄器件。为了实现高密度、自下而上的集成，通过范德华外延 (vdWE) 生长这些 2D 异质结构是目前最常用的机械转移的有吸引力的替代方案，后者在缩放和可重复性方面存在问题。控制核形成的位置仍然是 vdWE 中的一个关键挑战。在这里，聚焦 He 离子束用于确定性地将缺陷放置在石墨烯衬底中，这些缺陷用作绝缘 2D 六方氮化硼 (h-BN) 生长的优先成核位点。因此展示了无掩模的选择性区域 vdWE (SAvdWE)，其中 h-BN 的成核率和晶体质量由用于缺陷形成的离子束参数控制。此外，通过 SAvdWE 生长的 h-BN 显示出与机械转移层相当的电子隧道特性，从而为可靠、高密度的二维异质结构阵列制造奠定了基础，用于通过二维衬底中的缺陷工程进行器件集成。