High p-type conduction in high-Al content Mg-doped AlGaN

We report on the successful fabrication of highly conductive p-type Mg-doped Al0.7Ga0.3N thin films grown on sapphire substrates by metal-organic chemical vapor deposition. Photoluminescence measurements show that Mg doping for growth with a high V/III ratio and moderate Mg concentration can effectively suppress self-compensation by the formation of nitrogen vacancy complexes. The lowest electrical resistivity was found to be 47 Omega cm at room temperature. Moreover, the temperature dependence of the p-type conductivity in these high-Al content AlGaN films shows the extremely small effective activation energies of 47-72meV at temperatures below 500 K. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773594]