CHARACTERIZATION OF PHASE-SEPARATION IN AMORPHOUS FILMS USING MODERN SMALL-ANGLE SCATTERING METHODS

Small-angle X-ray scattering has been used as a structural tool to cha racterize phase separation in vapor-deposited amorphous thin films. Wh en combined with the anomalous dispersion effect, it becomes possible to differentiate voids from chemical inhomogeneity. These methods, as well as oblique transmission measurements, have been used to observe a nd characterize phase separation in sputtered amorphous MocGe1-c and F ecGe1-c alloys. The chemical inhomogeneities depend on the deposition conditions, are quite anisotropic and extremely small (10-30 Angstrom) , exist throughout a wide composition range (c < 0.33 for Fe-Ge and c < 0.25 for Mo-Ge), and are distinctly different in the Mo and Fe conta ining films. It is shown how it is possible to determine the endpoints of the phase separation, with results indicating endpoint composition s of amorphous Ge and an intermetallic phase of stoichiometry close to amorphous FeGe2 or MoGe3. Finally, with the use of cylindrical correl ation functions, it is demonstrated that small-angle X-ray scattering can be interpreted in terms of an anisotropic microstructure and prese nt straightforward growth models for phase separation in evolving, amo rphous films.