Angle-resolved photoemissions from a GaAs(111)-2×2 surface : normal emission study

Angle-resolved photoemission experiments using synchrotron radiation have been performed on an As-rich GaAs(111)-2×2 surface over the photon energy range 10-70 eV. The occupied bulk and surface band structures of the surface were investigated using theoretical structure plots involving the linear-muffin-tin-orbital (LMTO) calculated initial bands and free-electron-like final states. Based on a three-step model, the calculations suggest that this surface is rich in surface umklapp effects and that many strong transitions may be explained as surface umklapp transitions involving mainly the surface reciprocal lattice vector g 2×2 =2π/a(-1/3,2/3,-1/3)