X-ray photoelectron diffraction studies of this alloy surface have been carried out and indicate that there is a significant expansion of the lattice in the near-surface region due to the high concentration of Pd in layer 2. Preliminary single scattering calculations lend support to this proposal for the surface structure, and place this expansion in the subsurface mainly between layers 2 and 3.
ABSTRACTWe report on the first scanned-angle x-ray photoelectron diffraction measurements on GaN(0001) in the wurtzite structure, as grown on sapphire substrates using MOCVD. These as-grown samples reveal forward scattering peaks in agreement with a theoretical calculation using a single scattering cluster calculation. The surface contamination by O and C does not exhibit any clear structure. From the combination of experiment and theoretical calculation and from a simple intensity ratio argument the surface termination for these samples could be determined to be N. The data also indicate that C is on average closer to the GaN surface than O.
X-ray diffraction and extended x-ray absorption fine-structure characterization of nonspherical crystallographic grains in iron thin films