Extended Data Fig. 7: Characterization of as-grown single-crystal rBN films.
From: Bevel-edge epitaxy of ferroelectric rhombohedral boron nitride single crystal
a, AFM height mappings of transferred rBN films with typical thicknesses in the range of 2.2–12 nm. b, Statistics of the side length of separated domains at the nucleation stage. The average domain size is calculated to be 3.1 μm. c, Statistics of the average film thickness, exhibiting the nearly-linear dependence on the growth time. The estimated growth rate at the film-formation stage is 1.15 nm/h, which is consistent with the previously reported values (ref. 1: Nature 2022, 88, 606; ref. 2: Nano Letters 2016, 16, 3360). d, LEED patterns of the as-grown rBN film collected at different positions. The threefold symmetric patterns with consistent orientation confirm the single-crystal nature of the rBN lattice. e-h, UV-vis spectrum with an absorption peak at 6.1 eV (e), Raman spectrum with a characteristic E2g peak at 1368.5 cm−1 (f), and XPS spectra with B 1 s peak at 190.2 eV (g) and N 1 s peak at 397.9 eV (h), respectively, exhibiting the high quality of the as-grown rBN layers. i,j, In-situ SHG mappings of the rBN single-crystal films before (i) and after (j) etching, showing none of observed etched defect or thickness reduction. The same number corresponds to the same area, and all images are the same size.
