Stability of S and Se induced reconstructions on GaP(0 0 1)(2×1) surface

The structural and electronic properties of S- and Se-passivated GaP(0 0 1)(2×1) surfaces were studied using first-principles simulations. Our calculations showed that the most stable structure consists of a single chalcogen atom (S or Se) in the first crystal layer, which is bonded to two Ga atoms of the second layer, and the third P layer replaced by chalcogen atoms, similar to the passivation of GaAs(0 0 1)(2×1) surface by chalcogen atoms. The structural parameters were determined and the surface band characters and the local density of states were also analyzed. The results showed that the preferable structure has no surface states in the bulk band gap, but the energy band gaps of the S- and Se-adsorbed GaP(0 0 1) surfaces are 1.83 and 1.63 eV, respectively. The passivation effects for the S- and Se-adsorbed surfaces are similar to each other.