Diffuse X-ray scattering from polished silicon: application of the distorted wave Born approximation

Area of Science:

• Materials Science
• Surface Science
• Condensed Matter Physics

Background:

• Understanding surface topography is crucial for materials characterization.
• X-ray scattering techniques provide insights into surface structures.
• The distorted wave Born approximation (DWBA) is a theoretical framework for analyzing scattering data.

Purpose of the Study:

• To analyze diffuse X-ray scattering data from smooth and rough silicon surfaces.
• To correlate surface topography, characterized by power spectral density (PSD), with scattering behavior.
• To apply the distorted wave Born approximation (DWBA) to model the observed scattering.

Main Methods:

• Measured diffuse X-ray scattering data for silicon samples.
• Acquired power spectral density (PSD) data using atomic force microscopy and optical interferometry.
• Applied Fourier transforms of correlation functions to PSD data and integrated into the DWBA formalism.

Main Results:

• Identified distinct correlation functions for smooth (σ²=4 Ų) and rough (σ²=4900 Ų) silicon surfaces.
• Achieved good fits for the smooth sample across different scattering wavevector (qz) values using identical parameters.
• Observed significant differences in scattering patterns between smooth (clear distinction between specular and diffuse) and rough (weak specular, large Yoneda wings) samples.

Conclusions:

• The study successfully modeled surface roughness using a combination of correlation functions.
• DWBA, combined with PSD-derived correlation functions, effectively describes X-ray scattering from silicon surfaces.
• The distinct scattering behaviors highlight the impact of surface roughness on X-ray interactions.