Screw-Dislocation Driven Growth of Multilayer Hexagonal Boron Nitride

Abstract

Hexagonal boron nitride (h-BN) is an exceptional class of two-dimensional material because of its atomically flat surface, uniquely insulating nature and its high temperature and chemical stability. Controllable and large-scale synthesis of hexagonal boron nitride (h-BN) films has thus been extensively explored using chemical vapor deposition on various catalytic metals to enable the fabrication of scalable electronic devices. It is reported that the growth of h-BN is not self-limited and multilayer islands are observed after extended growth duration. Stranki-Krastanov model (island on layer) and inverted wedding cake model for h-BN multilayer are reported but the growth mechanism of such multilayer films is still not well discussed. In this work, we show that multilayer h-BN islands can be formed by screw-dislocation initiated at aligned domain boundary, using transmission electron microscopy. Unlike the single screw-dislocation growth observed on nanoplates or other 2D materials such as MoS2 or WS2, involvement of double screw-dislocation on growth process makes h-BN maintain its stable AA’ stacking configuration. Strain-induced topological defect, which is originated from the screw-dislocation, is also studied.