Synthesis of Hexagonal Boron Nitride Monolayer: Control of Nucleation and Crystal Morphology
by Yijing Stehle, et al.
A new era of electronics and even quantum devices could be ushered in with the fabrication of a virtually perfect single layer of “white graphene."
Monolayer hexagonal boronnitride (hBN) attracts signiﬁcant attention due to the potential to be used as a complementary two-dimensional dielectric in fabrication of functional 2D heterostructures. Here we investigate the growth stages of the hBN single crystals and show that hBN crystals change their shape from triangular to truncated triangular and further to hexagonal depending on copper substrate distance from the precursor. We suggest that the observed hBN crystal shape variation is aﬀected by the ratio of boron to nitrogen active species concentrations on the copper surface inside the CVD reactor. Strong temperature dependence reveals the activation energies for the hBN nucleation process of ∼5 eV and crystal growth of ∼3.5 eV. We also show that the resulting h-BN ﬁlm morphology is strongly aﬀected by the heating method of borazane precursor and the buﬀer gas. Elucidation of these details facilitated synthesis of high quality large area monolayer hexagonal boron nitride by atmospheric pressure chemical vapor deposition on copper using borazane as a precursor.