Superlattices and Microstructures vol:36 issue:4-6 pages:713-719
Deep level transient spectroscopy (DLTS) was used to investigate the electrical properties of GaN implanted with the rare earth (RE) ions erbium and thulium. The GaN layers have been grown by metal-organic chemical vapor deposition (MOCVD) onto (0001) sapphire substrates. We used the channeled implantation geometry to implant a dose of 5 x 10(14) RE cm(-2) with an energy of 150 keV. For each species, two different annealing procedures were used in a nitrogen atmosphere for 120 s. Indeed, the annealing temperature plays an important role in the lattice recovery, even if RE-related defects remain present. After annealing at 1000 degreesC, the appearance of two new peaks, for both studied RE ions, is associated with the lattice damage induced by the implantation, such as the presence of nitrogen vacancies. After annealing at 1100 degreesC, the recovery of the lattice is observed while a hole trap appears for both implanted RE ions with corresponding energy values E-v + 0.61 eV and E-v + 1.59 eV, in the case of Er and Tm, respectively. (C) 2004 Elsevier Ltd. All rights reserved.