Impact of Sequential N Ion Implantation on Extended Defects and Mg Distribution in Mg Ion-Implanted GaN

Abstract

In Mg ion implantation doping of GaN, sequential N ion implantation reportedly changes Mg concentrations in the Mg ion-implanted region and the underlying region after activation annealing. The impact of sequential N ion implantation on defects and Mg distribution after postimplantation annealing is investigated. The atomic-resolution analyses show that, in the Mg ion-implanted region, the N ion implantation increases the concentration of MgGa. It is thus concluded that the Mg soluble in GaN by Mg ion implantation is increased by N ion implantation. The rest of the Mg atoms agglomerate to form clusters on the extended defects, and their concentration is also increased by the N implantation. The coarsening of extended defects is suppressed by the N ion implantation: the defects in the MgþN-implanted sample are nanoscale interstitial-type defects, and they do not grow or annihilate after annealing. This indicates that the N implantation changes the concentrations of interstitials.