Effect of surface reconstruction on the low-temperature oxidation of InAs(100): Optical investigations

Using reflectance anisotropy spectroscopy (RAS), after identifying the main spectral lines, for the InAs(001) surfaces, we demonstrate that low-temperature (140 K) oxygen adsorption proceeds in a completely different way for the As-rich and for the In-rich surfaces. Oxygen is chemisorbed on the In-rich (4×2) surface, as found from the disappearance from the RA spectrum of the optical transitions due to surface dimers. The adsorbed oxygen cannot be removed by annealing, even up to 670 K. On the As-rich ${\beta }_2$ and ${\alpha }_2$ surface reconstructions, adsorption is limited to molecular physisorption: oxygen is desorbed by annealing at a significantly lower temperature of ≈300 K, and only weakly perturbs the signal related to surface dimers.