Effects of nitrogen impurities on the CVD growth of diamond: step bunching in 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 phase is investigated by experiments as well as by computer simulations. The adsorption of impurities on the diamond surfaces leads to step bunching, whereby complex two-dimensional patterns are formed. A mesoscopic Monte Carlo model is used to study this effect, whereby line tension, anisotropy in step propagation, roughness of steps and impurity strength are introduced on a physical basis. The similarity between experimental results and the step configurations resulting from simulations is remarkable. Furthermore, the coexistence of both step bunching and an increased growth rate upon nitrogen addition is explained by the fact that nitrogen on the surface has a different effect on the diamond growth than sub-surface nitrogen. This study gives a demonstration of a fruitful co-operation between computer simulations and real world experiments, which leads to a better understanding of the physical processes occurring during crystal growth. (C) 2000 Elsevier Science S.A. All rights reserved.