Mj. Regan et A. Bienenstock, CHARACTERIZATION OF PHASE-SEPARATION IN AMORPHOUS FILMS USING MODERN SMALL-ANGLE SCATTERING METHODS, Journal of non-crystalline solids, 193, 1995, pp. 644-652
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.