Catalyst‐Selective Growth of Single‐Orientation Hexagonal Boron Nitride toward High‐Performance Atomically Thin Electric Barriers

• Published in: Advanced materials (Weinheim) 2019-06, Vol.31 (24), p.e1900880-n/a
• Main Authors: Wang, Shengnan, Dearle, Alice E., Maruyama, Mina, Ogawa, Yui, Okada, Susumu, Hibino, Hiroki, Taniyasu, Yoshitaka
• Format: Article
• Language: English
• Subjects: Boron nitride; chemical vapor deposition; Crystal structure; Density functional theory; electric barrier; Electrical properties; hexagonal boron nitride; Interfacial strength; Layered materials; Materials science; Morphology; Orientation; Resistance; single orientation; Stability; Substrates; Thin films; Two dimensional materials; wrinkle‐free
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201900880

The ability to control the crystal orientation of 2D van der Waals (vdW) layered materials grown on large‐scale substrates is crucial for tailoring their electrical properties, as well as for integration of functional 2D devices. In general, multiple orientations, i.e., two or four orientations, appear through the crystal rotational symmetry matching between the material and its substrate. Here, it is reported that hexagonal boron nitride (h‐BN), an ideal electric barrier in the family of 2D materials, has a single orientation on inclined Cu (1 0 1) surfaces, where the Cu planes are tilted from the (1 0 1) facet around specific in‐plane axes. Density functional theory (DFT) calculation indicates that this is a manifestation of only one favored h‐BN orientation with the minimum vdW energy on the inclined Cu (1 0 1) surface. Moreover, thanks to the high interfacial strength with the underlying Cu, the single‐orientation h‐BN is free of thermal wrinkles, and exhibits a spatially homogeneous morphology and tunnel conductance. The findings point to a feasible approach to direct growth of single‐orientation, wrinkle‐free h‐BN thin film for high‐performance 2D electrical devices, and will be of benefit for controllable synthesis of other vdW materials. The catalyst surface selection rule of hexagonal boron nitride (h‐BN) growth by chemical vapor deposition is demonstrated. The catalyst‐terrace symmetry breaking by surface steps is proposed to be the key for single‐orientation growth of h‐BN on a series of inclined Cu (1 0 1) facets. The single‐orientation h‐BN is free of wrinkles and exhibits excellent homogeneity of dielectric performance.