Polarity dependence of Mn incorporation in (Ga,Mn)N superlattices

•Introducing (Ga,Mn)N/GaN:Mg superlattices for achieving high p-type and Mn doping.•At high Mg fluxes, a drop in Mn concentrations of factor 100 to 1000 is observed.•The drop is shown to be linked to a polarity inversion caused by high Mg fluxes.•Comparison of Mg and Mn behaviour validates an analogy between underlying physics.

In the context of recent efforts to combine high Mn concentrations in (Ga,Mn)N with a pronounced p-type carrier density, (Ga,Mn)N/GaN:Mg-superlattices have been fabricated using plasma-assisted molecular beam epitaxy. Profiles of the dopant atomic densities in the heterostructures are obtained by secondary ion mass spectroscopy. They show an abrupt drop of two to three orders of magnitude in both Mn and Mg concentrations after the first GaN:Mg layer above a critical Mg-flux. Scanning electron microscopy before and after selective etching reveals a polarity inversion from originally Ga-face to N-face GaN in samples in which high Mg fluxes were applied. From our observations, we are able to draw an analogy between the impurity incorporation laws of Mg and Mn.