On the effect of ion implantation in the microstructure of GaN: an XAFS study

Nitrogen K-edge EXAFS measurements are used to study the effect of N+ and O + implantation in the microstructure of GaN. In the as-grown sample the cen tral N atom is four-fold coordinated with 3.35 Ga atoms at the expected dis tance of 1.93 Angstrom, and 0.65 displaced to a distance longer by similar to 0.33 Angstrom. Implantation with either N or O ions enhances the distort ion in the microstructure and the number of the displaced Ga atoms increase s from 0.65 to 1. The enhancement of the distortion in the coordination num ber is attributed to the generation of excess N vacancies. In addition to t hat implantation causes a reduction in the nearest neighbor distances by ab out 2% and an increase of the Debye-Waller factors.