Different bonding states of Cs and O on highly photoemissive GaAs by flash−desorption experiments

Abstract

The thermal desorption of Cs and O from GaAs/Cs/O activated to negative electron affinity occurs as atomic Cs133 and (mostly) Ga2O. Flash−desorption experiments show that several bonding states exist for the adsorbed Cs which correlate with changes in work function. For example, (i) the Cs bonding state for GaAs/Cs changes when the Cs coverage exceeds that required for maximum photoemission, and (ii) the distribution of bonding states for Cs shifts markedly to higher energies as the GaAs surface passes from unactivated (GaAs/Cs) to activated (GaAs/Cs/O).