Microstructural and electrical characterization of Er and Eu implanted gallium nitride

Transmission electron microscopy and deep levels transient spectroscopy (DLTS) are used to investigate Er/Eu implanted GaN layers. We used random and channeled implantation. Microstructural analysis shows that both ion implantation geometries exhibit similar defects. For the Er doped samples, the investigated annealing conditions leave a highly disordered surface layer and the fabricated diodes exhibit high leakage currents. The Eu doped samples have reasonably good electrical characteristics and an additional deep level which might be associated with the presence of the implantation damage. We also point out two levels which have already been observed in undoped GaN, but whose energy position is displaced probably due to the strain or defects after ion implantation.