Homoepitaxy of boron nitride on exfoliated hexagonal boron nitride flakes

The experimental data presented is related to the article: Binder, J., Dabrowska, A. K., Tokarczyk, M., Rousseau, A., Valvin, P., Bozek, R., Nogajewski, K., Kowalski, G., Pacuski, W., Gil, B., Cassabois, G., Stepniewski, R., & Wysmolek, A. (2024). Homoepitaxy of boron nitride on exfoliated hexagonal boron nitride flakes. Nano Letters, https://doi.org/10.1021/acs.nanolett.4c01310.Data in FigS4.zip presents PL spectra for different regions on the sample: on a homepitaxial triangular grain, on the bulk hBN flake and next to the flake on the sapphire substrate.Although large efforts have been made to improve the growth of hexagonal boron nitride (hBN) by heteroepitaxy, the non-native substrates remain a fundamental factor that limits the quality. This problem can be solved by homoepitaxy, which is the growth of hBN on hBN substrates. In this report, we demonstrate the homoepitaxial growth of triangular BN grains on exfoliated hBN flakes by Metal-Organic Vapour Phase Epitaxy and show by atomic force microscopy and photoluminescence that the stacking of these triangular islands can deviate from the AA’ stacking of hBN. We show that the stacking order is enforced by the crystallographic direction of the edge of the exfoliated hBN flakes, with armchair edges allowing for centrosymmetric stacking, whereas zigzag edges lead to the growth of non-centrosymmetric BN polytypes. Our results indicate pathways to grow homoepitaxial BN with tuneable layer stacking, which is required to induce piezoelectricity or ferroelectricity.