Fast Crystallographic Texture Mapping of Atomically-Thin hBN Films on Ni(111) Using Secondary Electron Contrast

High-throughput characterisation and rapid quality feedback play pivotal roles in accelerating advanced materials development and expand their horizon of applications. This is particularly pertinent for the chemical vapor deposition (CVD) driven industrialisation of ultra-thin device materials, like hBN, where complex texture at atomic layer level remains hard to characterise and thus feedback loops and workflow remain slow.[1] Scanning electron microscopy (SEM) is a well-established technique particularly for facile characterization of emerging 2D materials, where secondary electron (SE) contrast allows rapid and non-destructive mapping of monolayer domains and films on a wide range of substrates. Here, we show that SE contrast generated by surface-sensitive in-lens detectors can be used to fingerprint monolayer hBN domains alignment to the Ni(111) surface, thus opening fast crystallographic texture mapping capabilities with conventional SEM.[2] This is supported by density functional theory (DFT) computations indicating a work function difference of 50 meV between the two anti-parallel epitaxial hBN orientations, and of around 600 meV between epitaxial and non-epitaxial (rotated) hBN orientations, where we also account for realistic vicinal Ni surfaces. We demonstrate how this enables the effective and systematic analysis of the large-area structure of hBN CVD films and gives insight in their evolution, including the nature of resulting domain boundaries [3] and bilayer regions.<br/><br/>[1] Wang et al. ACS Nano 13, 2114 (2019)<br/>[2] Babenko et al, submitted<br/>[3] Bayer et al. ACS Nano 11, 4521 (2017)