Photoelectron diffraction studies on the structure of sulfur-passivated InP(100) and CaF2 layers grown on S/InP(100)

The structure of an (NH4)(2)S-x-treated surface of InP(100) and CaF2 epitaxial layers grown on S/InP(100) has been studied by X-ray photoelectron diffraction (XPED). Single-scattering cluster calculations with spherical-wave scattering (SSC-SW) for the (1 x 1) bridge-site model give a good description of the XPED from the S overlayer. In addition, we found that there is little anion exchange reaction between P and S in the process of (NH4)(2)S-x treatment. On the other hand, the XPED results for the CaF, thin films revealed that CaF2 grows epitaxially on S/InP(100) as CaF2(100) islands. In particular, the lattice of the film is strained at the initial stages of epitaxy, owing to the CaF2-InP lattice mismatch. We determined the lattice strains along the lateral and vertical directions by comparing the experimental and theoretical angular distributions of Ca2p and F 1s intensities. (C) 1997 Elsevier Science B.V.