The lattice location of low-dose implanted Er in GaN, GaN:O, and GaN:C was investigated using the emission channeling technique. The conversion electrons emitted by the probe isotope Er-167m give direct evidence that the majority (approximate to90%) of Er atoms are located on substitutional Ga sites for all samples. Annealing up to 900degreesC does not change these fractions, although it reduces the Er root-mean-square (rms) displacements. The only visible effect of oxygen or carbon doping is a small increase in the rms displacements with respect to the undoped sample. (C) 2004 American Institute of Physics.