Mg-modified surface kinetics of the GaN growth by molecular beam epitaxy

The influence of Mg on the growth kinetics of GaN deposited by plasma-assisted molecular-beam epitaxy has been studied. It has been found that surface diffusion and/or the residence time of both N and Ga were drastically influenced by the presence of Mg on the surface. This leads to an abrupt phase transition from a low-mobility state to a high mobility state for the Ga atoms onto the surface when increasing the Ga/N flux ratio above a critical value. A Ga droplet density has been evaluated by a simple nucleation model, and found to be in agreement with experimental observations.