Angle-resolved photoemission and valence band dispersions {A figure is presented} for GaAs: Direct vs indirect models

Angle-resolved photoemission measurements for GaAs(110) have been extended to hv= 100 eV. These results show that dominant emission peaks are due to direct transitions. Weaker one-dimensional density of states features sometimes observed are due to surface umklapp/secondary cone and lifetime effects. Accurate band dispersions {A figure is presented} for all four valence bands GaAs along the [110] direction are given using simple normal emission and off-normal emission methods. Electron and hole lifetimes are directly determined. © 1979.