posted on 2019-03-07, 00:00authored byHyo Ju Park, Roland Yingjie Tay, Xiao Wang, Wen Zhao, Jung Hwa Kim, Rodney S. Ruoff, Feng Ding, Edwin Hang Tong Teo, Zonghoon Lee
Among the different
growth mechanisms for two-dimensional (2D)
hexagonal boron nitride (h-BN) synthesized using chemical vapor deposition,
spiraling growth of h-BN has not been reported. Here we report the
formation of intertwined double-spiral few-layer h-BN that is driven
by screw dislocations located at the antiphase boundaries of monolayer
domains. The microstructure and stacking configurations were studied
using a combination of dark-field and atomic resolution transmission
electron microscopy. Distinct from other 2D materials with single-spiral
structures, the double-spiral structure enables the intertwined h-BN
layers to preserve the most stable AA′ stacking configuration.
We also found that the occurrence of shear strains at the boundaries
of merged spiral islands is dependent on the propagation directions
of encountering screw dislocations and presented the strained features
by density functional theory calculations and atomic image simulations.
This study unveils the double-spiral growth of 2D h-BN multilayers
and the creation of a shear strain band at the coalescence boundary
of two h-BN spiral clusters.