BN analogues of graphene: On the formation mechanism of boronitrene layers — solids with extreme structural anisotropy

Boron nitride is an extremely useful material for applications in material sciences and appears in a manifold of crystalline modifications, with hexagonal and cubic boron nitride as most prominent substances. In hexagonal boron nitride, threefold coordinated boron and nitrogen atoms form two-dimensional layers, which resemble the boron nitride analogue of graphene layers, and we refer to this two-dimensional network as boronitrene layers. So far, there is little knowledge about the elementary growth reactions of these boronitrene layers.Here we show that it is possible to regenerate a previously prepared 14 × 14 BN/13 × 13 Rh(111) superstructure [obtained by CVD of borazine (B3N3H6)] after an oxidation step from an unordered monolayer of a boron–oxygen compound by chemical reactions induced by ammonia as nitrification agent on the surface. The individual steps of the experiment were controlled by a LEED- and XPS- analysis and indicate that the original BN superstructure can be recovered without traceable amounts of oxygen in the film. The presented results indicate that highly mobile species from the B–N–O–H system can be considered as surfactants in the elementary formation and degradation reactions of highly ordered boronitrene layers. An understanding of these reactions is a fundamental issue in tuning the crystal growth and quality of the BN phases.