Local charge redistribution at potassium adsorption on the Si 111/7=7 surface: a scanning tunneling microscopy study

The adsorption process of potassium on the Si 111.7=7 surface has been studied by scanning tunneling microscopy STM.. The adsorption of K proceeds in two stages. In the first stage K atoms adsorb ionically with their s-states above EF and the charge transfer occurs efficiently on the faulted halves. The first adlayer develops to the entire faulted and unfaulted regions with the K-induced states above EF. At higher coverages the second stage., K atoms tend to form neutral clusters preferentially in faulted regions. The electronic structure around the clusters is markedly modified, which suggests a local charge redistribution. The STM observations well explain measured work function variation. q1999 Elsevier Science B.V. All rights reserved.