  The structural analysis of GaN and Al$_x$Ga$_{1-x}$N/GaN heterostructures
grown by metalorganic vapor phase epitaxy in the presence of Mn reveals how Mn
affects the growth process, and in particular the incorporation of Al, the
morphology of the surface, and the plastic relaxation of Al$_x$Ga$_{1-x}$N on
GaN. Moreover, the doping with Mn promotes the formation of layered
Al$_x$Ga$_{1-x}$N/GaN superlattice-like heterostructures opening wide
perspective for controlling the segregation of ternary alloys during the
crystal growth and for fostering the self-assembling of functional layered
structures.
