Effect of amorphous interface layers on crystalline thin-film x-ray diffraction

Abstract

In this work, an analysis method of x-ray diffraction data of crystalline structures with amorphous interface layers is presented and applied to single crystalline films on amorphous interface layers. Thickness and morphology of crystalline films are obtained from x-ray diffraction at conditions where no significant interference effects between crystalline film and substrate occur. Extending the x-ray diffraction analysis to conditions where interference effects between the crystalline film and the substrate appear, it is also possible to determine the morphology of the amorphous interface film. The analysis method presented in this work is useful for the current and future analyses of amorphous structures between crystalline structures in general and is therefore applicable to many different material systems. This incorporates crystalline thin and ultrathin films on crystalline substrates as well as crystalline multilayers on crystalline and also on amorphous substrates. We apply the method developed here to characterize both crystalline praseodymia films and amorphous interface layers, which could be detected neither by x-ray reflection nor by x-ray diffraction previously.

Post-deposition annealing of praseodymia films on Si(111) at low temperatures

“…Those effects are enhanced and complicated by an amorphous silicate interface which acts as a spacer between the two crystalline structures [17]. Hence, in the following, the region at L ≈ 2 is used for crystal truncation rod (CTR) analysis since the praseodymia peak intensity is still adequate for detailed analysis while the Si peak intensity is small.…”

Photoemission study of praseodymia in its highest oxidation state: The necessity of in situ plasma treatment

“…As discussed before, 8,20,23 the diffraction intensity close to the Si(111) Bragg peak contains the full information about both the vertical lattice constant and the film thickness of the praseodymia films as well as the interface distance and interface roughness due to the interference between substrate and film. Diffraction close to the Si(222) Bragg peak, however, which is forbidden according to kinematic diffraction theory, is only sensitive to the diffraction from the praseodymia film so that this diffraction condition is better suited to characterize quantitatively the praseodymia film itself and to avoid complications with respect to the interference between film and substrate.…”

Silicate-free growth of high-quality ultrathin cerium oxide films on Si(111)

“…Physically, these characteristics can be related to a phase shift between the diffracted beams of the crystalline overlayer and the substrate, which is attributed to the existence of an amorphous buffer layer. 29 A quantitative XRD analysis according to Ref. 29 based on the kinematic theory of x-ray diffraction [represented by the solid line in Fig.…”