Investigation of Mg doping in high-Al content p-type AlxGa1−xN (0.3<x<0.5)

A study of Mg doping of AlxGa1−xN up to x∼50% using microstructural and electrical probes is reported. The viability of effective p-type doping is defined by a minimum concentration of Mg required to offset the background impurities and, more importantly, a maximum limit above which inversion domains and structural defects start to nucleate, accompanied by a rapid degradation of electrical transport. Resistivity of 10 Ω cm and free hole concentrations above 1017cm−3 are achieved for AlxGa1−xN up to x∼50% within an optimum window of Mg incorporation.