MBE growth of GaN films in presence of surfactants: the effect of Mg and Si

摘要

We present here a description and an analysis of the modifications in the growth behavior of GaN induced by the presence of foreign species. The particular cases of Mg and Si are analyzed. Profound changes, both in microscopic and macroscopic scales, occur in presence of Mg, even for fluxes of about 1/1000{sup}th of the Ga flux. The growth rate can be increased by almost 50％, depending of theⅢ/V ratio and on the amount of Mg. A theoretical model is proposed to describe the observed effect. It is found that Mg induces changes in the Ga and N diffusion barriers and acts as a surfactant. The effect is stronger on theα-GaN than on theβ-GaN, where N is more tightly bonded. The effect of Si is by far less pronounced, probably because it is more easily incorporated than Mg, and its effect on the surface kinetics is then strongly reduced.