Effects of nitrogen impurities on the CVD growth of diamond: step bunchingin theory and experiment

The step flow dynamics during homoepitaxial diamond deposition on vicinal { 001} diamond surfaces in the presence of nitrogen impurities in the gas pha se is investigated by experiments as well as by computer simulations. The a dsorption of impurities on the diamond surfaces leads to step bunching, whe reby complex two-dimensional patterns are formed. A mesoscopic Monte Carlo model is used to study this effect, whereby line tension, anisotropy in ste p propagation, roughness of steps and impurity strength are introduced on a physical basis. The similarity between experimental results and the step c onfigurations resulting from simulations is remarkable. Furthermore, the co existence of both step bunching and an increased growth rate upon nitrogen addition is explained by the fact that nitrogen on the surface has a differ ent effect on the diamond growth than sub-surface nitrogen. This study give s a demonstration of a fruitful co-operation between computer simulations a nd real world experiments, which leads to a better understanding of the phy sical processes occurring during crystal growth. (C) 2000 Elsevier Science S.A. All rights reserved.