X-ray reflectivity of chemically vapor deposited diamond single crystals in the Laue geometry

TL;DR

This study measures the absolute X-ray reflectivity of CVD diamond single crystals in Laue geometry, analyzing the data with the Darwin-Hamilton approach and revealing inhomogeneity in crystal microstructure.

Contribution

It provides the first detailed analysis of CVD diamond reflectivity in Laue geometry using the Darwin-Hamilton model, highlighting microstructural inhomogeneity.

Findings

Reflectivity curves are influenced by strong extinction effects.

Two different parameter sets were identified for the 111 asymmetric reflection.

Inhomogeneity in the crystal microstructure affects reflectivity measurements.

Abstract

Absolute X-ray reflectivity of chemically vapor deposited (CVD) diamond single crystals was measured in the Laue geometry in the double-crystal non-dispersive setting with an asymmetric Si beam conditioner crystal. The measurements were supplemented by rocking curve topography. The measured reflectivity curves are examined in the framework of Darwin-Hamilton approach using a set of two independent parameters, the characteristic thickness of mosaic blocks and their average angular misorientation. Due to strong extinction effects the width of reflectivity curves does not directly represent the average misorientation of the blocks. Two different sets of parameters were found for the 111 asymmetric reflection in the two different scattering configurations (beam compression and beam expansion). Analysis of the rocking curve topographs shows that this discrepancy can be attributed to inhomogeneity of the diamond crystal microstructure.