Al (110) surface oxide thermal stability in ultrahigh vacuum

This research characterizes the stability of the Al₂O₃ surface oxide on Al (110) as a function of temperature and within an ultrahigh vacuum environment (p < 5 × 10^?12 Torr). Auger electron spectroscopy and temperature desorption spectroscopy were used to correlate the change in oxygen and carbon surface concentration. The surface oxide was observed to remain stable up to 350–400 °C. Above this temperature, the oxide began to dissociate resulting in a CO desorption peak at 425 °C followed by extensive dissolution of the C and O into the Al bulk. A second and much smaller CO desorption peak was observed at 590 °C in concert with complete oxide breakdown and the virtual disappearance of surface carbon and oxygen. Extrapolation of the Auger electron spectral ratios of C_KLL and O_KLL peaks to the sum of the Al⁰_LVV and Al³⁺_LVV peak suggests that the surface concentration of each approaches zero at ~640 °C. The predominant mechanism for reduction of the surface oxide occurs by dissolution into the bulk instead of desorption. Copyright © 2013 John Wiley & Sons, Ltd.