Quantitative Auger analysis of gold-copper-oxygen and gold-nickel-oxygen surfaces using relative sensitivity factors

Abstract

Quantitative Auger analysis is becoming routine for unoxidized binary allowys. Many specimens of technological importance, however, contain large amounts of oxygen, which can complicate quantitative analysis by changing (a) peak shapes (e.g. ] ne widths, δ), (b) energy position of the peaks, (c) Auger currents, and (d) the sputtering correction factor ( R). This paper describes quantitative Auger analysis of the gold- copper-oxygen and gold-nickel-oxygen systems, based on relative sensitivity factors before ( P rel) and after ( P s rel) sputtering. The relative sensitivity factors, ( P s rel) were found to be independent of the gold and oxygen concentrations for both systems. In the gold-copper-oxygen system this is attributed to the sharpness of the 920 eV (LMM) copper transition compared to the energy resolution (0.6%) of the CMA analyzer used. For the gold-nickel-oxygen system it is ascribed to a fortuitous cancellation of two effects (1) increased line width, δ, hence a decreased 848 eV (LMM) peak height upon oxidation, and (2) increased Auger emission of the 848 eV peak due to oxidation. A single crystal standard of Cu 2O was used to confirm the 2 : 1 ratio of Cu to O in the ternary samples. The sputtering correction factors were found to be R(O, Cu) = 1.0 for the composition of Cu 2O and R(O, Ni) = 0.72 for the composition NiO. The variation in R with Au concentration is negligible. The major limitation on the quantitative Auger analysis of these ternary systems has been found to be uncertainty in the sputtering correction Factor R. Nomographs for calculating concentrations for constant C o/ C Cu and C O/ C Ni using ( P s rel) are also presented.