Growth of aligned and twisted hexagonal boron nitride on Ir(110)

The growth of monolayer hexagonal boron nitride (h-BN) on Ir(110) through low-pressure chemical vapor deposition is investigated using low energy electron diffraction and scanning tunneling microscopy. We find that the growth of aligned h-BN on Ir(110) requires a growth temperature of 1500 K, whereas lower growth temperatures result in coexistence of aligned h-BN with twisted h-BN. The presence of the h-BN overlayer suppresses the formation of the nanofaceted ridge pattern known from clean Ir(110). Instead, we observe the formation of a (1 x n) reconstruction, with n such that the missing rows are in registry with the h-BN/Ir(110) moire pattern. Our moire analysis showcases a precise methodology for determining both the moire periodicity and the h-BN lattice parameter on an fcc(110) surface. Aligned h-BN on Ir(110) is found to be slightly compressed compared to bulk h-BN, with a monolayer lattice parameter of a(h-BN) = (0.2489 +/- 0.0006) nm. The lattice mismatch with the substrate along [1 (1) over bar0] gives rise to a moire periodicity of a(m) = 2.99 +/- 0.08 nm.