Fig. 3: Characterization of commercial CVD-grown h-BN samples labelled as monolayer from Suppliers 1 and 2.

Panels a–f and panels g–l are taken in samples from Suppliers 1 and 2 (respectively). a, b and g, h Cross-sectional high-resolution transmission electron microscopy (TEM) images of different areas of the CVD-grown h-BN samples labelled as monolayer from Suppliers 1 and 2. For both samples, ~80% of the sample looks like panels a and g (~2 nm-thick), and ~20% like panels b and h (amorphous); no monolayer area is detected. c, i Top-view scanning electron microscopy (SEM) images of the samples, showing long wrinkles and some brighter (i.e., multilayer) regions. d, e and j, k CAFM topography and current maps were collected simultaneously at the same area of each sample without applying any bias. f, l 100 I–V curves collected at random locations of each sample.