Nitrides and their interfaces with metals studied by means of electron spectroscopies

Au/GaN and Pt/GaN contacts have been studied with x-ray photoelectron spectroscopy (XPS). According to XPS depth profiling, the interfaces are rather sharp, with the exception of a thin layer of Au-Ga or Pt-Ga alloy at the interface. A detailed study of the formation of Au contacts on GaN and of the effect of ion beam irradiation has shown that there is little or no interaction between Au and GaN, and that Ar ions induce the formation of a Au-Ga alloy at the interface. The same is thought to be the case for Pt/GaN. Annealing the Au/GaN samples results in clustering and leads to strong differential charging during the XPS measurements. Therefore, special care must be taken when analyzing apparent binding energy shifts in the corresponding core-level spectra.