Erbium was implanted into (00▪1) epitaxial GaN grown on sapphire with an energy of 80keV and a dose of 2.5 x 1014Er/cm2. Rutherford back-scattering and channeling spectrometry were used to investigate the effect of the implantation geometry upon defect generation. The defect density was significantly reduced when implanting along the GaN c-axis and gradually increases when changing the implantation angle towards random implantation (i.e. 10° off the c-axis). A rather large critical angle of ~6.5° was found, indicating that channeling of the Er ions occurred easily. The generated defects expand the GaN lattice in the implanted region, which resulted in a satellite peak in the high-resolution X-ray diffraction spectra. After annealing the samples at 950C for 30 min in N ambient, a reduction in defect density as well as a relaxation of the GaN lattice towards the bulk value was observed for all implantation angles.

Influence of the Implantation Angle on the Generation of Defects for Er Implanted GaN. B.Pipeleers, S.M.Hogg, A.Vantomme: Nuclear Instruments and Methods in Physics Research B, 2003, 206, 95-8