Abstract
Temperature dependent photoluminescence (PL) in the ultraviolet (UV) regime and Hall measurements at room temperature have been performed on Metal‐Organic‐Chemical‐Vapour‐Deposition (MOCVD) grown GaN:Fe and (Ga,Fe)N:Mg layers. PL measurements were employed in order to study the dopants' influence on the near‐band edge excitonic emission and their tendency to provoke the formation and suppression of defects or incorporation of impurities. For their identification and for the understanding of the PL spectra the evaluation of the free carrier concentrations via Hall measurements were necessary. Depending on the iron concentration of the (Ga,Fe)N layers, the near‐band edge emission goes through two different stages: at low Fe‐concentration no excitonic emission can be seen whereas with higher doping levels, excitonic features develop. The (Ga,Fe)N films exhibit n‐type behaviour. The Mg codoped samples show strong Mg and defect related luminescence bands, whose occurrence and intensity also strongly depends on whether high or low Fe concentration is present. The (Ga,Fe)N:Mg layers were semi insulating. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)