Synthesis of sub-millimeter single-crystal grains of aligned hexagonal boron nitride on an epitaxial Ni film

Alexandre Budiman Taslim, Hideaki Nakajima, Yung Chang Lin, Yuki Uchida, Kenji Kawahara, Toshiya Okazaki, Kazu Suenaga, Hiroki Hibino, Hiroki Ago

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Hexagonal boron nitride (h-BN), an insulating two-dimensional (2D) layered material, has attracted increasing interest due to its electrical screening effect, high-temperature-resistant gas barrier properties, and other unique applications. However, the presence of grain boundaries (GBs) in h-BN is a hindrance to obtain these properties. Here, we demonstrate the epitaxial growth of monolayer h-BN by chemical vapor deposition (CVD) on Ni(111) thin films deposited on c-plane sapphire. The Ni(111) films showed higher thermal stability than Cu(111) and Cu-Ni(111) alloy films, allowing us to perform CVD growth at a high temperature of 1100 °C. This resulted in an increase of the h-BN grain sizes to up to 0.5 millimeter, among the highest reported so far, and in a well-defined triangular grain shape. Low-energy electron microscopy (LEEM) revealed the epitaxial relationship between h-BN and the underlying Ni(111) lattice, leading to a preferential alignment of the h-BN grains. Both the large grain size and the alignment are expected to facilitate the synthesis of h-BN with a low density of GBs. We also found that the addition of N2 gas during the CVD improves the crystalline shape of the h-BN grains, changing from an irregular, truncated to a sharp triangle. The growth behavior of monolayer h-BN is further discussed in terms of the dependences on growth temperature and pressure, as well as on the structural evolution of the Ni metal catalyst. Our findings not only help understand the h-BN growth mechanism but also offer a new route to grow high-quality, monolayer h-BN films.

Original languageEnglish
Pages (from-to)14668-14675
Number of pages8
JournalNanoscale
Volume11
Issue number31
DOIs
Publication statusPublished - Aug 21 2019

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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