XPS and AFM studies of surface chemistry and morphology of In2O3 ultrathin films deposited by rheotaxial growth and vacuum oxidation after air exposure

In this paper we present the results of an XPS study of the surface chemistry of In2O3 (IO) ultrathin deposited by rheotaxial growth and vacuum oxidation after their air exposure and subsequent UHV annealing. For the freshly deposited RGVO IO ultrathin films the relative [O]/[In] concentration is equal to 1.17 +/- 0.05. After exposure to air it increases to 1.25 +/- 0.05. However, a strong C contamination appears, confirmed by the relative [C]/[In] concentration that is equal to 1.07 +/- 0.05. After subsequent UHV annealing at 200 degrees C the relative [O]/[In] concentration remains and only slightly increases to 1.30 +/- 0.05 after subsequent UHV annealing at 350 degrees C. After this process the relative [C]/[In] concentration decreases to 0.43 +/- 0.05. The additional AFM experiments showed that the RGVO IO ultrathin films exhibit the granular-type surface morphology, with an average grain height and width in the range of 2-5 nm, and 10-50 nm, respectively, and an average roughness of 1.1 nm.