Growth Mechanism of High-Quality hBN Monolayers on Cu through Chemical Vapor Deposition with Inductively Coupled Plasma

The growth mechanism associated with the nucleation and growth kinetics of hexagonal boron nitride (hBN) on Cu through chemical vapor deposition (CVD) has been studied. A fully covered hBN film with a large grain size has been obtained by lowering the density of the grain boundary during the thermal CVD. The Cu substrate is first annealed under the H2 ambiance in order to efficiently reduce the copper oxide on the surface and promote the Cu surface with the (111) plane. Next, the nucleation and growth kinetics of CVD hBN are investigated by the analysis of scanning electron microscopy (SEM) images and the Johnson-Mehl-Avrami-Kolmogorov model. The hBN growth is overall dominated by nucleation under a low flow rate of H2, while it is initially dominated by grain growth under a high flow rate of H2 and the grain size of hBN can be larger than 25 μm. The competition between nucleation and grain growth is reversed at higher temperatures, resulting from the wavier Cu surface. Furthermore, the hBN film is grown by the inductively coupled plasma-enhanced CVD (ICP-CVD) and its growth mechanism is compared with that of CVD hBN. The growth rate of ICP-CVD hBN is 50 times faster than that of CVD hBN due to more energetic B and N species caused by plasma. The growth mechanism of ICP-CVD hBN without a long incubation time is dominated by nucleation.