Effect of fluence on the lattice site of implanted Er and implantation induced strain in GaN

A GaN thin film was implanted with 5 x 10(14) cm(-2) of 60 keV stable (166)Er, followed by the implantation of 2 x 10(13) cm(-2) radioactive (167)Tm (t(1/2) = 9.3 d) and an annealing sequence up to 900 degrees C. The emission channeling (EC) technique was applied to assess the lattice location of Er following the Tm decay from the conversion electrons emitted by (167m)Er, which showed that more than 50% of (167m)Er occupies substitutional Ga sites. The results are briefly compared to a (167m)Er lattice location experiment in a GaN sample not pre-implanted with (166)Er. In addition, high-resolution X-ray diffraction (HRXRD) was used to characterize the perpendicular strain in the high-fluence implanted film. The HRXRD experiments showed that the Er implantation resulted in an increase of the c-axis lattice constant of the GaN film around 0.5-0.7%. The presence of significant disorder within the implanted region was corroborated by the fact that the EC patterns for off-normal directions exhibit a pronounced angular broadening of the order of magnitude of 0.5 degrees. (C) 2009 Elsevier B.V. All rights reserved.