DAFS Experiments with Non-Centrosymmetric Single Crystals

Abstract

Diffraction anomalous ®ne structure (DAFS) experiments were applied to an epitaxially grown (Ga,In)P layer on a [001] GaAs substrate as a single-crystalline model substance. The requirements for the reliable measurement of re¯ection intensities as a function of photon energy, as well as the quantitative DAFS analysis resulting in the complex-valued ®ne-structure function of the scattering factor, are described. In the case of single crystals, effort had to be put into performing the DAFS measurements in order to hold the position of the Bragg re¯ection exactly during the energy scan. Using the zinc-blende-type structure as an example, it is shown for the ®rst time that, similar to singlecrystal structure analysis, the lack of inversion symmetry has a signi®cant impact on the DAFS signal, so that DAFS may contribute to structure analysis as well.

Determination of polarity in noncentrosymmetric layer/substrate systems

“…For the sake of simplicity, the variable energy E is not indicated. An expression for the energy dependence of diffracted intensity has been given elsewhere (Meyer et al, 1998), taking the oscillating terms f H os Ga and f HH os Ga into account. Fig.…”

Grazing Incidence Diffraction Anomalous Fine Structure in the Study of Structural Properties of Nanostructures

“…For instance, in case of samples in which different local environments coexist, XAFS spectroscopy may fail to give pertinent information since, due to the lack of spatial selectivity, all the different environments are probed. to correct the data for self-absorption when measuring bulk samples (see, for instance, [16,17]). No use to say how interesting it can be for both absorption and diffraction scientific communities.…”

“…16 EXAFS spectra (a) and the corresponding Fourier transforms (b) for GaN QDs grown on AlN substrate with 10 MLs AlN capping. The labels parallel and perpendicular refer to light polarization of X-ray.…”

Revisit to diffraction anomalous fine structure

“…This restriction is not the case in single-crystal measurements. Even in a noncentrosymmetric single crystal, the simultaneous equations can be solved, as both hkl and " h h " k k " l l reflections with different DAFS spectra (Meyer et al, 1998) can be separately measured.…”