A. J. G. Leenaers

Application of genetic algorithms for characterization of thin layered materials by glancing incidence X-ray reflectometry

A genetic algorithm for characterization of thin-layered materials by glancing incidence X-ray reflectometry is proposed. For both simulated and measured data good fits are obtained within a single run. This reduces the amount of human effort and expertise necessary for analyzing reflectivity measurements which makes genetic algorithms an attractive alternative to methods currently used.

Applications of Glancing Incidence X-Ray Analysis

In many technological applications layered materials have an increasing importance. Almost complete characterization of such materials can be achieved with glancing incidence x-ray analysis (GIXA). Within this technique, x-ray reflectivity and angle-dependent x-ray fluorescence measurements are combined, resulting in a structural and chemical analysis of the samples.

Probing interface roughness by X-ray scattering

Abstract X-ray scattering at glancing angles can be exploited to probe interface roughness. Various theories for this technique will be reviewed. The applicability of the theories is shown to depend on the relevant length scales of sample and X-rays. Approximations are discussed and improvements of the theory are suggested. Both specular reflection, diffuse scattering and absorption of X-rays will be discussed. It will be shown that relevant roughness parameters, like root-mean-square roughness, lateral and perpendicular correlation lengths and the degree of jaggedness can be extracted from the experiments. Possible forms for the roughness correlation function are discussed. As an example, it is shown how the interface roughness of an oxidic multilayer has been probed by X-ray scattering.

Glancing incidence X-ray analysis: more than just reflectivity!

Many analytical methods can be used to characterize thin-layered materials. Glancing incidence X-ray analysis (GIXA) has the potential to be a powerful and versatile analytical method because it combines X-ray reflectivity (XRR) and glancing incidence X-ray fluorescence (GIXRF). In this way, layer thickness, roughness and the elemental depth profile of the material can be obtained. In addition, non-specular measurements contain a wealth of information on the lateral roughness structure of the layer interfaces.

The profile of layered materials reflected by glancing-incidence X-ray analysis

Specular reflectivity, diffuse scattering at glancing incidence and angle-dependent total-reflection X-ray fluorescence are complementary techniques for the investigation of layered materials. The principles of these glancing-incidence X-ray methods are briefly discussed. Examples show the strength of the combination of these techniques.

Specular and non-specular X-ray reflection from inorganic and organic multilayers

Specular and non-specular X-ray reflectivity measurements can be exploited to obtain interesting properties of layered materials such as electron-density profile and lateral and perpendicular structure of interface roughness. This will be illustrated using results on a nickel–carbon multilayer and a liquid-crystalline polymer.

X-ray reflectometry from samples with rough interfaces: an oxidic-multilayer study

The possibilities for the investigation of thin-layered samples by specular and non-specular X-ray reflectivity and angle-dependent X-ray fluorescence are shown. As an example, measurements on an oxidic multilayer are discussed. Layer thickness, interface roughness and conformality, as well as compound formation at the interfaces, are found in an unambiguous way. Also, the lateral structure of the interface roughness can be described and is tentatively interpreted in terms of terrace widths.