Large-area adlayer-free single-layer h-BN film achieved by controlling intercalation growth

Controllable wafer-scale growth is one of the ultimate goals in two-dimensional (2D) h-BN synthesis, which is not fully accomplished to date. One of critical issues is the formation of three-dimensional (3D) islands (adlayers) within 2D layers, thus the films are non-uniform in thickness. In this paper, we present a study of h-BN adlayer growth and provide a strategy towards eliminating these adlayers for the precise control of the number of 2D layers. By varying the growth parameters such as substrate property, nitrogen source composition, and substrate carburization time, we found that the adlayer growth can be controlled by controlling the nucleation and intercalation processes, which is achieved by engineering the defects and impurities on substrate and the activeness of the h-BN edges. While crystallographic defects and impurities stimulate the multilayer nucleation process, activated edge tends to turn off the intercalation process by reducing the probability of precursors penetrating into the interface. We have achieved the growth of a large-area adlayer-free single-layer h-BN film.