Multilayers suppressed growth of hexagonal boron nitride on copper by nitrogen

Wei Yu Huang^1*, Woon Wei Yen¹

¹Physics, National Central University, Taoyuan, Taiwan

* Presenter:Wei Yu Huang, email:hyes92250@gmail.com

Monolayer hexagonal boron nitride (hBN) is an atomically thin two-dimensional material with sp2 structure. Large band gap, without dangling bonds, and stable physical and chemical properties make hBN an extraordinary van der Waals stacking layers for insulator and supported material.
In our previous work, pure hydrogen is confirmed to control nucleation and growth kinetics of hBN on copper to produce over 25um single crystal grain. However, we found that multilayers hBN would simply form under pure hydrogen growth might due to the hydrogen edge terminal of hBN grain. Also, the mechanism of hBN growth of controlled layer number is not clear yet. Here, we perform strategies to grow high quality monolayer hBN and understand the mechanism.
We study the synthesis mechanism through the nucleation and growth kinetics of hBN on copper. Its nucleation density and growth are the result of competition between the diffusion of the surface B/N adatoms and etched desorption rate. Introducing nitrogen during growth decrease the ratio of hydrogen which reduce the hydrogen edge terminal of hBN grain. Furthermore, the lowering of etching rate from hydrogen reserves more N adatoms on copper surface which promote the monolayer hBN grain growth because of hBN triangular geometry with N zigzag edge on copper which need more N atoms to form large single grain. With certain gas ratio of N2/H2 we produce high quality uniform monolayer hBN. SEM, Raman spectrum, AFM, and TEM are used to confirming the properties and understanding nucleation and growth kinetics of hBN.

Keywords: hexagonal boron nitride, 2D material, CVD