Fe ion implantation in GaN: Damage, annealing, and lattice site location

In this article we report the damage and annealing behavior as well as lattice site location of Fe atoms in GaN. The Fe ions were homogeneously implanted in GaN films with an energy of 150 keV at room temperature. A two-step annealing (650 degreesC 15 min and then 1000 degreesC 2 min) was performed to remove the implantation-induced damage and to drive the dopants into the lattice site. The structure of GaN films before and after the implantation as well as at each stage of the annealing was characterized by Rutherford backscattering/channeling combined with particle induced x-ray emission and high resolution x-ray diffraction. The Fe+ implanted GaN films exhibits an expanded lattice. After the two-step annealing, the lattice distortion does not fully recover. Angular scans along both [0001] and [10 (1) over bar1] directions show that the Fe atoms occupy the lattice site of Ga atoms in the case of low dose implantation after annealing. However, for the high dose implanted GaN, about 75% of the implanted Fe atoms substitutes Ga atoms, showing that the damage is not annealed out and the dopants are not completely activated. (C) 2001 American Institute of Physics.