Synchrotron radiation x-ray photoelectron spectroscopy is used for the study of 5 nm Si nanocrystals (NCs) for applications in nonvolatile memory devices. A detailed peak shape analysis of the high-resolution Si2p core-level spectra reveals average chemical shifts for the oxidized components consistent with those observed for planar oxidation. However, a much larger Gaussian width is found for each spectral component, reflecting the important level of structural disorder in the NCs, arising from stress produced during the kinetics of the oxide shell growth. Final state contributions to the core-level spectra are also discussed.