Röntgenreflektometri

Röntgenreflektometri, often abbreviated as XRR, is a non-destructive technique used to analyze thin films and layered structures. It exploits the phenomenon of X-ray reflection at grazing incidence angles. When X-rays strike a smooth surface or interface between two materials with different refractive indices, they can be reflected. The angle of incidence and the wavelength of the X-rays are crucial parameters in this process.

In XRR, the sample is illuminated with X-rays at very small angles, typically below 5 degrees. As the angle of incidence is varied, the intensity of the reflected X-rays is measured. This intensity shows oscillations, known as Kiessig fringes, which are directly related to the thickness of the thin film. The positions of these fringes allow for precise determination of film thickness, often down to the nanometer scale.

Beyond thickness, XRR can also provide information about the density and roughness of the thin film. The decay rate of the reflected intensity at higher angles is sensitive to the film's density, while the reduction in the amplitude of the Kiessig fringes can indicate surface or interface roughness. By fitting the experimental data to theoretical models, a comprehensive understanding of the layered structure can be obtained. XRR is widely applied in fields such as semiconductor manufacturing, optics, and materials science for quality control and research.