Auger electron spectra of Mg thin films

The effect of oxidation on Mg thin films is studied by Auger electron spectroscopy. Several films are prepared from Mg of purity 99.999% under a pressure of ${10}^{-6\mathrm{}}$-${10}^{-8\mathrm{}}$ Torr in the thickness range 200-25 000 ÅA. The spectra from these films are measured on an ESCA-36 spectrometer with $\mathrm{Al} K\alpha$ excitation line under a pressure of about ${10}^{-8\mathrm{}}$ Torr. The minimum of $\mathrm{Au}(5\mathrm{}s-6d)$ band at 5.0 eV, and the maximum of $\mathrm{C}\left(1\mathrm{}s\right)$ line at 284.6 eV were used as reference lines for calibration of the observed spectra. The contamination effect due to ${\mathrm{O}}_2$ is found to decrease with increasing film thickness. There was a marked change in the peak heights of all the Auger lines accompanied by substantial peak shifts towards the higher energy with oxidation. It is speculated that this resulted from the gettering action of the active Mg metal with the residual ${\mathrm{O}}_2$ in the deposition environment. In particular, the $K{L}_1{L}_3$ transition was extremely sensitive in that it disappeared rather quickly with minimal oxidation. The Auger transition shifts for both chemisorbed oxide and stoichiometric oxide are measured to be 4.7 and 6.2 eV, respectively.