Coadsorption of Cs and O on GaAs: formation of negative electron affinity surfaces at different temperatures

The electronic states during different stages of the NEA surface formation of the GaAs(100)–O/Cs coadsorption system have been investigated with photoemission using synchrotron radiation at RT and 100 K. It was found that the core level peak shifts for early steps of NEA surface formation differ between the two temperatures. An analysis of the core level peak shifts and the increase in peak height during the oxidation of Cs monolayers shows that the observed values are comparable with those of bulk Cs and Cs layers on other substrates. Later steps of NEA surface formation do not differ between experiments carried out at RT and 100 K.