Crystal polarity effects on magnesium implantation into GaN layer

Crystal polarity effects on Mg implantation into GaN layers for p-type doping have been systematically investigated. It is found that we can observe a smaller X-ray diffraction full-width at half-maximum and a stronger Mg-acceptor bound exciton emission for the Mg implantation into Npolarity GaN layer than Ga-polarity one after a proper post-implantation annealing treatment. Raman experiment demonstrates that the tensile stress occurs on the as-grown N-polarity GaN layer, which can be resulting from the Ga vacancy. Hall measurement results further indicate that the p-type conductivity can be successfully obtained for N-polarity GaN compared with Ga-polarity one after Mg implantation regardless of under the identical implantation and post-implantation annealing conditions. These phenomena can all be attributed to the more Ga vacancies in the asgrown N-polarity GaN layer that enhances Mg acceptor substitution and eventually achieve p-type conductive characteristics by an appropriate postimplantation annealing treatment.