THE COADSORPTION OF CESIUM AND POTASSIUM ON SI(100)

An experimental investigation of K and Cs coadsorption on Si(100)2 × 1 surface at RT took place in an UHV system by LEED, AES, TDS and work function measurements. The results suggest that the sites of K and Cs on Si(100)2 × 1 are different and the individual saturation coverage of the two alkali is the same. During successive coadsorption the two alkali are coadsorbed collaterally in an additive manner to cover the substrate and form a mixed adlayer with a saturation coverage of ~ 50% higher than that of each alkali alone. When the first alkali adsorbate on Si(100) is saturated, the following deposition of the second alkali causes a decrease of the absolute coverage of the first. This is due to a partial removal of the atoms of the first alkali by those of the second. The above process is independent of the sequence of deposition of K and Cs adsorbates. © 1990.