Interface structure studies of copper thin films on C-plane sapphire by crystal truncation rod analysis using synchrotron x-ray

The surface structure of the bare {dollar}alpha{dollar}-{dollar}rm Alsb2Osb3{dollar} single crystal substrate and the interface of and {dollar}rm Csb6sb0/alpha{dollar}-{dollar}rm Alsb2Osb3{dollar} system were studied. It was to obtain a systematic understanding about the effect of the substrate on the resulting structures of the {dollar}rm Cu/alpha{dollar}-{dollar}rm Alsb2Osb3{dollar} system, and on the film properties. Discussion was focused on the crystal truncation rod (CTR) data of {dollar}rm Cu/alpha{dollar}-{dollar}rm Alsb2Osb3{dollar} system measured by synchrotron X-ray at NSLS, BNL. Data taken by other surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and in situ reflection high-energy electron diffraction (RHEED) were also discussed.; Thin films were grown by UHV-MBE technique. The substrates underwent two different heat treatments prior to Cu deposition. One substrate was annealed in air at {dollar}1500spcirc{dollar}C for 3 hours followed by an anneal in UHV at {dollar}1200spcirc{dollar}C for 30 minutes prior to Cu deposition. The other substrate was not subjected to any high-temperature annealing except for an intermediate temperature cleaning treatment at {dollar}600spcirc{dollar}C before deposition. The CTR from a clean sapphire substrate without Cu coverage and {dollar}rm Csb6sb0/alpha{dollar}-{dollar}rm Alsb2Osb3{dollar} were measured as a reference. The measured data were fitted to the theoretical equation of diffracted crystal truncation rod intensity profile based upon the kinematical approximation. The CTR analysis method provide us the nature of the terminating layer sequence of the substrate, the structural relaxations (interatomic distance change) of the layers near the surface and the interfacial roughness.