Self-terminating growth in hexagonal boron nitride by metal organic chemical vapor deposition

Abstract

In this work, we demonstrate the growth of atomically smooth few-layer hexagonal boron nitride (h-BN) on sapphire substrates by metal organic chemical vapor deposition using triethylboron (TEB) and NH3 as precursors. Changing the V/III ratio in a certain temperature and pressure range was found to change the growth mode from random 3D nucleation to self-terminating growth. Infrared reflectance and Raman spectroscopy were used to identify the h-BN phase of these films. Atomic force microscopy measurements confirm that the surfaces are smooth and continuous even over atomic steps on the surface of the substrate. Using X-ray reflectance measurements, the thicknesses of films grown under self-terminating conditions were determined to be ∼1.6 nm and independent of the growth time (1 to 60 min) and TEB flux rate. On the basis of the results of this study, a possible mechanism for the observed self-terminating growth behavior is discussed.