Auger electron spectroscopy sputter depth profiling technique for binary solids

In this work the Auger electron spectroscopy (AES) sputter depth profiling technique for binary solids has been discussed and exemplified by its application to reveal composition profiles generated in Ni0.7Mo0.3 by pre-bombardment with Ar+-ions of 1 through 5 keV. Two element-specific, surface-sensitive Auger transitions are employed to monitor the surface composition. The linear correlation between the Auger intensities provides the relative sensitivity factor for the quantification of AES data. A model proposed by Ho and co-workers is reformulated for the conversion of the measured temporal variation of surface concentration Cs(t) into the original composition profile C(x). Radiation-enhanced diffusion caused by high-energy ion bombardment turns sputter depth profiling into an underdetermined inverse problem. On the other hand, experiments show that the strong preferential sputtering effect accompanying low-energy sputter may veil the detail of the composition profiles. An intermediate energy between about 100 and 300 eV is found to be optimum for the purpose of sputter depth profiling.