This letter reports the results from using angle-resolved x-ray photoelectron spectroscopy to nondestructively characterize ultrathin high-k SrTiO3 (STO) films. Results indicate that carbon is present in the STO film in the form of SrCO3 which is amorphous. SrCO3 concentration varies as a function of its position in the film as measured by the take-off angle (TOA). For films annealed at 650 °C, the C 1s, O 1s, and Sr 3d photoelectron transitions indicate a significant reduction in the carbonate. There is Sr enrichment on the surface, and the composition gradually converges to stoichiometric STO with Sr/Ti∼1 at higher TOA.