Energy correction by evaporated gold in x-ray photoelectron spectroscopy

Abstract

This work reports measurements of the binding-energy shift of gold evaporated on several insulating materials including polymers such as polytetrafluoroethylene and polyethylene and inorganic materials such as silicon oxide. The Au binding energy showed higher values than that for bulk gold in the initial stage of deposition even after correction for charging effects. The energy shifts seen for the polymer substrates were smaller to those for inorganic materials such as silicon oxide and silicon nitride. The thickness of gold necessary to obtain the bulk Au binding energy was small for substrates whose Au binding-energy shifts were small. Thus, it was confirmed that it is very important to deposit an appropriate amount of gold to obtain the correct binding energies. These results can be explained by extra-atomic relaxation, because a larger extra-atomic relaxation energy is expected for substrates on which gold atoms or clusters can migrate easily and form larger clusters. These clusters cause smaller binding-energy shifts and require smaller amounts of evaporated gold.