Structure and bonding in photodiffused amorphous Ag-GeSe2thin films

Grazing-incidence x-ray scattering (GIXS) techniques have been used to study the local and intermediate-range order in photodiffused amorphous Ag-${\mathrm{GeSe}}_{2}$ thin films and a variety of Ag-Ge-Se alloys. Using synchrotron-radiation sources, the GIXS technique can be used in conjunction with radial-distribution-function analysis, differential anomalous x-ray scattering, and differential distribution-function analysis to study the structure of very thin amorphous films. With these techniques, we have determined that the local atomic structure of Ag-${\mathrm{GeSe}}_{2}$ films satisfies a model where Se-Ag dative bonds are formed, one Se-Ag covalent bond is formed for each Ag atom added (below a critical composition), and Ge-Ge bonds are created as Ag is added. This last result significantly modifies the intermediate-range order in this system.