Nickel adsorption and incorporation on a 2 × 2-T4 GaN(0 0 0 1) surface: A DFT study

Abstract

We have performed first-principles calculations of energetic stability and electronic structure of nickel adsorption and incorporation on a 2×2 reconstructed GaN(0001) surface. Our total energy results show that the most stable positions of a Ni adatom on the reconstructed 2×2-T4 GaN(0001) surface are at the H3a0 and T4 adsorption sites. We found that the Ni adatom diffusion energy barrier between the H3a0 and T4 sites is around 0.16eV, 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 NiGax and Ni monolayers on the GaN(0001) surface is possible.