Crystallographic orientation dependence of dopant and impurity incorporation in GaN films grown by metalorganic chemical vapor deposition

In this study we investigated the incorporation of the dopants Si, Mg, and Fe and the unintentional impurities O and C in GaN films grown on mm-plane (101¯0), aa-plane (112¯0) as well as semi-polar (101¯1), (101¯1¯), (112¯2), and (112¯2¯) bulk GaN substrates by metalorganic chemical vapor deposition. GaN layer stacks were grown under various growth conditions and analyzed by secondary ion mass spectroscopy. Whereas the dopant incorporation was little affected by the crystallographic orientation, differences were observed in the doping profiles, in particular for Mg and Fe doping. Significant variations were observed in the impurity incorporation. While N-rich surfaces exhibited a high affinity towards O incorporation in general, C incorporation trends were strongly dependent on the specific growth conditions.