A laboratory x-ray diffractometer for surface and thin-film studies is
presented. Ex situ structural characterization of FeSi2 films epitaxi
ally grown on Si(111) is reported. Both specular and nonspecular refle
ctivities are measured on beta-FeSi2 films grown by solid-phase epitax
y 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 i
s also measured at grazing incidence. For the beta-FeSi2 sample invest
igated, the (110) epitaxy on Si(111) is clearly shown. For a film grow
n by molecular-beam-epitaxy codeposition at 550-degrees-C, the existen
ce of a new metastable phase which is in registry with silicon along t
he Si[1BAR 10] direction and slightly out of registry, (3.0+/-1.0)% co
mpressed along the Si[112BAR] direction, is reported.