X‐ray scattering studies of FeSi2 films epitaxially grown on Si(111)

A laboratory x‐ray diffractometer for surface and thin‐film studies is presented. Ex situ structural characterization of FeSi2 films epitaxially grown on Si(111) is reported. Both specular and nonspecular reflectivities are measured on β‐FeSi2 films grown by solid‐phase epitaxy and reactive deposition epitaxy techniques. A detailed comparison is performed of the electron density profile of the films normal to the surface, as well as of their surface roughness. In‐plane diffraction is also measured at grazing incidence. For the β‐FeSi2 sample investigated, the (110) epitaxy on Si(111) is clearly shown. For a film grown by molecular‐beam‐epitaxy codeposition at 550 °C, the existence of a new metastable phase which is in registry with silicon along the Si〈1 10〉 direction and slightly out of registry, (3.0±1.0)% compressed along the Si〈112〉 direction, is reported.