Influence of O and C co-implantation on the lattice site of Er in GaN

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 $^{167m}$Er give direct evidence that the majority (~90%) of Er atoms are located on substitutional Ga sites for all samples. Annealing up to 900 °C 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