Effects of transition metal ions doping on optical and electronic properties of GaN

Transition metal ions Co, Cr, Mn and V were implanted at 200 keV into GaN thin films at three different doses 5 × 1014, 5 × 1015 and 5 × 1016 cm−2 and then thermally annealed to recover the lattice from implantation induced damages. In order to access the modification in optical properties of the samples, detailed photoluminescence investigations were carried out at room temperature and low temperatures. The emission related to band edge of the material is observed un-shifted for all samples but lower in intensity whereas several new luminescence centers appeared after implantation. The emission observed for pure GaN at 3.44 eV is enhanced after implantation whereas newly observed line at 3.35 eV appeared only after implantation at highest dose of 5 × 1016 cm−2. The decrease in intensity of existing emission lines of the material is assigned to implantation induced non-radiative recombination centers whereas emergence of new peaks is allocated to dopant related gap states as per predictions made by our first principles calculations.