High-Quality Hexagonal Boron Nitride from 2D Distillation.

Cun, Huanyao; Miao, Zichun; Hemmi, Adrian; Al-Hamdani, Yasmine; Iannuzzi, Marcella; Osterwalder, Jürg; Altman, Michael S; Greber, Thomas · ACS Nano · 2021

basic_science · Level V

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Abstract

The production of high-quality two-dimensional (2D) materials is essential for the ultimate performance of single layers and their hybrids. Hexagonal boron nitride (<i>h</i>-BN) is foreseen to become the key 2D hybrid and packaging material since it is insulating, impermeable, flat, transparent, and chemically inert, though it is difficult to attain in ultimate quality. Here, a scheme is reported for producing single layer <i>h</i>-BN that shows higher quality in view of mosaicity and strain variations than material from chemical vapor deposition (CVD). We delaminate CVD <i>h</i>-BN from Rh(111) and transfer it to a clean metal surface. The twisting angle between BN and the second substrate yields metastable moiré structures. Annealing above 1000 K leads to 2D distillation, <i>i.e.</i>, catalyst-assisted BN sublimation from the edges of the transferred layer and subsequent condensation into superior quality <i>h</i>-BN. This provides a way for 2D material production remote from CVD instrumentation.