Revealing the nucleation mechanism of CVD-prepared hexagonal boron nitride on transition metal surfaces: A study from DFT calculations

Abstract

Hexagonal boron nitride (h-BN) has a promising application in the field of electronic devices due to its many unique properties, but the nucleation mechanism of h-BN on transition metal surfaces in chemical vapor deposition (CVD) experiments is still unclear. Here, we systematically investigated the formation energy and stability of h-BN clusters on 10 kinds of transition metal surfaces using density functional theory (DFT) calculations. The results show that h-BN clusters on different metal substrates may undergo the transition to the most stable structure at a critical size, but the critical size is different for different metal substrates. For the BN clusters on Ag(111) surface, the ground-state structures are chain-like and ring-shaped configurations at n ≤ 4 and 4 < n ≤ 11, respectively, then the honeycomb becomes the most stable one when the size of BN clusters increases to n = 12. The most stable structures for BN clusters on Cu, Pd and Co surfaces change from chain-like to sp2 honeycomb at the critical size of n = 8, 7 and 8, respectively. Thereafter, the honeycomb structure becomes the most energetically favourable one and continues to grow until it covers the entire substrate. Efficient charge transfer from underlying metals and highly symmetric structures are key factors for the stabilization of BN clusters. The study of BN nucleation on an atomic scale is helpful to improve experimental conditions and design experiments for the preparation of h-BN films or other two-dimensional (2D) materials.