Structural characterization of thin layered materials using x-ray standing wave enhanced elastic and inelastic scattering measurements

Abstract

By measuring the intensities of the x-ray standing wave induced elastic and inelastic x-ray scattering from thin multilayer structures, we show that structural characterizations of the high and low z (atomic number) material layers can be performed independently. The method has been tested by analyzing the structural properties of an Nb/C/Nb trilayer and an Mo/Si periodic multilayer structure. The results of the x-ray scattering measurements have been compared with those obtained using x-ray reflectivity and conventional x-ray standing wave fluorescence techniques. It has been demonstrated that the present approach is especially suitable for studying multilayer structures comprising low atomic number layers, as it eliminates the requirement of a fluorescence signal, which is very weak in the case of low z materials.

Oscillating dipole model for the X-ray standing wave enhanced fluorescence in periodic multilayers

“…It appears that our calculation is in agreement with the data reported in [4]. As a second example in the dBM, we consider the Mo/Si multilayer system studied by Tiwari and Sawhney [5]. The structure has 20 bilayers; the thickness of the Mo layer is the experimental data [2,3].…”

“…The primary incident field can generate photoelectrons, fluorescence emission and be elastically (Rayleigh) or inelastically (Raman-Compton) scattered. The production of secondary X-rays makes it possible to probe the structure by different ways: as mentioned in reference [5], XSW enhanced fluorescence is rather interesting to analyse high-Z layers since photoelectric cross sections scales as Z 4 while the elastic or inelastic scattering profiles are more sensitive to the cross sections of low Z materials. Modelling these emissions generally consists in:…”

“…X-ray Bragg diffraction by a periodic multilayer structure gives rise to a system of Xray standing waves (XSW) that can be profitably used to determine the microstructural properties of the stack [1][2][3][4][5][6]; by adjusting the grazing angle  0 in the Bragg domain, it is possible to localize the peaks of electric field intensity within the structure in the regions of interest for the analysis. The primary incident field can generate photoelectrons, fluorescence emission and be elastically (Rayleigh) or inelastically (Raman-Compton) scattered.…”

Co/Mo2 C multilayer as X-ray mirror: Optical and thermal performances

“…While X‐ray reflectometry is a well‐established technique to determine the characteristics (thickness, density, optical index) of thin films , EFXSW in the soft‐X‐ray range is only at its early stages compared to hard‐X‐ray SW . Recently, some of us have developed a model based on the emission of a radiating dipole embedded in a multilayer structure to describe the EFXSW .…”

“…Thus, in addition to studying the optical performance of Co/Mo 2 C multilayers in both hard and soft X-ray regions, we show in the present work that it is possible to determine the optical index (nik) of a Co nanofilm in the Co/Mo 2 C multilayer system near the Co L3 edge by combining these three methods. While X-ray reflectometry is a well-established technique to determine the characteristics (thickness, density, optical index) of thin films [6], EFXSW in the soft-X-ray range is only at its early stages compared to hard-X-ray SW [10]. Recently, some of us have developed a model based on the emission of a radiating dipole embedded in a multilayer structure to describe the EFXSW [11].…”