Conquering sealing problems of gaps: hydrogen assisted edge growth of h-BN

Edge kinetics in two-dimensional structure has been a key to understanding the growth. In this talk, we illustrate intrinsic difficulty of filling a gap of last few atoms on zigzag edges of hexagonal boron nitride, defined as a sealing problem. The physical origin of the problem is due to formation of dimers that largely distorted the edge structure. Specifically, the distortion becomes severe and creates a large growth barrier for the attachment of the last atom and degrades the crystal quality. To solve the sealing problem and reduce the energy barrier, it's possible to passivate the dangling bonds of the edge atoms with H to reduce the edge distortions. This new finding and growth strategy may largely enhance the crystal quality and growth rate.