Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms vol:206 pages:95-98
Erbium has been implanted into (0001) epitaxial GaN grown on sapphire with an energy of 80 keV and a dose of 2.5 x 10(14) Er/cm(2). Rutherford backscattering and channelling spectrometry were used to investigate the effect of the implantation geometry on the defect generation. The defect density is significantly reduced when implanting along the GaN c-axis and gradually increases when changing the implantation angle towards random implantation (i.e. 10degrees off the c-axis). A rather large critical angle of -6.5degrees is found, indicating that channelling of the Er ions occurs easily. The generated defects expand the GaN lattice in the implanted region, which results in a satellite peak in the high-resolution X-ray diffraction spectra. After annealing the samples at 950 degreesC for 30 min in nitrogen ambient, a reduction in defect density as well as a relaxation of the GaN lattice towards the bulk value is observed for all implantation angles. (C) 2003 Elsevier Science B.V. All rights reserved.