Mn incorporation in GaN thin layers grown by molecular-beam epitaxy

GaMnN layers have been grown by MBE on Si(111) in a wide range of growth conditions. For different substrate temperatures the structural and composition dependence of the grown layers has been studied as a function of the Mn supply. We find that at regular substrate temperature the incorporation of Mn into the layer is low and difficult to control. Only at a reduced substrate temperature of 650 degrees C and under N-rich growth conditions it is possible to grow homogeneous GaMnN layers if the Mn supply is below 15% of the total metal flux. The incorporation efficiency in this range is about 30%, which corresponds to a maximum Mn content in the diluted layers of about 5%. Above a critical Mn supply, GaMn3N precipitates are formed, which often extend out of the surface with a typical pyramidal structure.