Changes in electronic and adsorption properties under Cs adsorption on GaAs(1 0 0) in the transition from As-rich to Ga-rich surface

The method of threshold photoemission spectroscopy is used to investigate both the ionization energy and photoelectron yield as a function of Cs dosage on the gradually reconstucted GaAs(1 0 0) surface in the transition from As-rich to Ga-rich. The difference in the Cs dosages to achieve the minimum of ionization energy is found to exist for the As-rich and Ga-rich surfaces. Anomalous curves with two minima of ionization energy as a function of Cs dosage are found for the intermediate reconstructed GaAs(1 0 0) surface, which indicates the existence of multi-domain phases with both the As-rich and Ga-rich domains. The Cs sticking coefficient on Ga-rich surface is found to be three times more than that on As-rich surface. It is established that Cs adsorbs initially on Ga domains and then on As domains. Perceptible temperature decrease of Cs sticking coefficient on As-rich domains is evident from the data of Cs deposition on the intermediate reconstructed surface at various substrate temperatures. It is shown that the technique of dosage-dependent-photoelectron yield with s-polarized excitation provides accurate analysis of surface phase evolution.