(001) Surfaces of GaP and InP: structural motifs, electronic states and optical signatures

Abstract We present ab initio calculations on the energetics and geometry, as well as electronic and optical properties of InP and GaP(001) surfaces. Cation-rich conditions lead to the formation of asymmetric cation–anion dimers on top of a (2×4) reconstructed cation-terminated surface. Anion-rich surfaces form c(4×4) reconstructions. Based on the DFT-LDA electronic structure, we compute the reflectance anisotropy of the energetically favoured (2×4) reconstructions. Strong anisotropies in the low-energy region arise from transitions between σ-like cation–cation bonding states and empty dangling bonds. Transitions involving P dimer states and surface modified bulk wave functions contribute at higher energies. The application of GW corrections leads to non-uniform shifts of characteristic peaks and changes the line shape, considerably improving the agreement with experiment.