Low temperature growth of h-BN on graphene via molecular beam epitaxy

Hexagonal boron nitride has emerged as a fundamental building block for atomically thin electronic devices. This contribution investigates its formation on graphene via molecular beam epitaxy at temperatures well below 1300°C, where it is considered metastable as a bulk material. However, it is shown that even at lower temperatures single- to few-layer hexagonal boron nitride still nucleates on graphene, and that the formation of the sp
²
- and sp
³
-bonded phases of BN can be manipulated via an in-situ N
2
-plasma pretreatment of the substrates. Here the experimental discovery of a novel, metastable, sp
³
-bonded phase, which so far has been only predicted theoretically, demonstrates a rich polymorphism in BN at the nanoscale.