Raman measurements and photoluminescence (PL) were performed on the metal-organic chemical-vapor deposition epitaxially grown GaN before and after the implantation with Er and Er+O. Several Raman defect modes have emerged from the implantation-damaged samples. The structures around 300 and 595 cm-1 modes are attributed to the disorder-activated Raman scattering, whereas the 670 cm-1 peak is assigned to nitrogen-vacancy-related defect scattering. One additional peak at 360 cm-1 arises after Er+O coimplantation. This Raman peak is attributed to the O-implantation-induced defect complex. The appearance of the 360 cm-1 mode results in the decrease of the Er3+ -related infrared PL intensity for the GaN:Er+O samples.