Cs-induced charge transfer on (2x4)-GaAs(001) studied by photoemission

TL;DR

This study investigates how cesium adsorption affects charge transfer and surface structure on GaAs (001), revealing coverage-dependent charge transfer behavior and surface phase changes upon annealing.

Contribution

It provides detailed insights into the coverage-dependent charge transfer mechanisms and surface phase transformations induced by Cs on GaAs (001).

Findings

Charge transfer to Ga is complete at low coverage.

Charge transfer to As occurs at higher coverage.

Cesium induces surface disordering and phase change after annealing.

Abstract

Cesium adsorption on 2x4 GaAs (001) was studied by photoemission and low energy electron diffraction. The different Cs induced changes of the As 3d and Ga 3d core level spectra show that charge transfer is almost complete for Ga surface sites, but is negligible to surface As at a coverage smaller than 0.3 ML. The situation is opposite for a coverage larger than 0.3ML, at which transfer occurs to As but no longer to Ga. Charge transfer to As atoms leads to disordering and destabilization and induces surface conversion from the As-rich surface to the Ga-rich 4x2 one after annealing at a reduced temperature of 450 C.