Fig. 2: Oxygen-assisted growth of hexagonal-shaped hBN on Cu(111).
From: Single-crystal hBN Monolayers from Aligned Hexagonal Islands
a, b False-color scanning electron microscopy (SEM) images of as-grown hBN on Cu(111) foils with triangular (a) and hexagonal islands (b). c SEM image of as-grown well-aligned hexagonal-shaped hBN islands on the Cu(111) substrate. d, e Raman maps of the CuOx intensity (\(I_{{{{\mathrm{CuO}}}}_{{\mathrm{x}}}}\)) measured on the triangle- (d) and hexagonal-shaped hBN islands (e). f, g Raman spectra taken from ∼ 100 random locations of bare Cu (f) and hBN-covered (g) regions. The compared spectra collected from the marked positions in (e) are shown in the inset of (g). h, i Atomic force microscopy (AFM) topography (h) and conductive AFM current map (i) of as-grown hexagonal-shaped hBN island on Cu(111) substrate after the oxidation treatment. j, k I–V curves collected from 77 and 66 random positions in the area of as-grown hexagonal- (j) and triangle-shaped (k) hBN islands on Cu(111) by applying ramped voltage stresses from 0 to 10 V to the tip. l, m Statistical analysis of the onset voltages for hexagonal-shaped (l) and triangle-shaped (m) hBN islands. The solid lines show fitted distribution curves, illustrating the differences in onset voltages between the two island shapes.
