Nickel adsorption and incorporation on a 2 × 2-T_4 GaN(0 001) surface: A DFT study

摘要

We have performed first-principles calculations of energetic stability and electronic structure of nickel adsorption and incorporation on a 2 × 2 reconstructed GaN(0 001) surface. Our total energy results show that the most stable positions of a Ni adatom on the reconstructed 2 × 2-T_4 GaN(0 0 01) surface are at the H_3~(aO)f and T_4 adsorption sites. We found that the Ni adatom diffusion energy barrier between the H_3~(aO) and T_4 sites is around 0.16 eV, which is an indication of a significant Ni adatom diffusion on this surface. In addition, calculating the relative surface energy of several configurations, we constructed a phase diagram showing the energetically most stable surfaces as a function of the Ga chemical potential. Based on these results, we found that Ni adsorption is energetically more favorable compared with Ni incorporation in the Ga-substitutional and interstitial sites. In addition, confirming previous experimental results, we found that the growth of NiGa_x and Ni monolayers on the GaN(0 001) surface is possible.