First-principles study of indium adsorption on GaP(0 0 1)(2 x 1) surface

We applied first-principles calculations to investigate the structural and electronic properties of indium adsorption on the GaP(0 0 1) surface at the coverages (Θ) of 0.5 and 1 ML. It was found that at Θ = 0.5 ML In adatoms preferred to adsorb at the pedestal (HH) site, followed by the bridge site. This is similar to the In/GaAs (0 0 1) adsorption system. For the coverage of 1 ML, the most stable configuration is a combination of the HH and valley bridge (T3) or cave (T4) sites, with the energy difference of only 30 meV between HH-T3 and HH-T4 sites adsorption. The density of states (DOS) analysis showed that the deposition of pure indium on GaP substrate can be employed as surface passivation of underlying buffered layers. The obvious hybridization of In 5p and P 3p states was observed in the conduction bands. The work function change due to In adsorption was calculated to be -1.01 and ∼-1.66 eV at the coverages of 0.5 and 1 ML, respectively, indicating that some charges are transferred from the adsorbate to the substrate