Thermal Annealing Characteristics of Si and Mg-implanted GaN Thin Films

In this letter, we report the results of ion implantation of GaN using ²⁸Si and ²³Mg species. Structural and electrical characterizations of the GaN thin films after thermal annealing show that native defects in the GaN films dominate over implant doping effects. The formation energies of the annealing induced defects are estimated to range from 1.4 to 3.6 eV. A 30 keV10^¹⁴ cm^-2 Mg implant results in the decrease of the free-carrier concentration by three orders of magnitude compared to unimplanted GaN up to an annealing temperature of 690 °C. Furthermore, we have observed the correlation between these annealing-induced defects to both improved optical and electrical properties.