Determination of lateral block size and mosaicity of crystals using X‐ray diffraction from the edge of the sample

Abstract

In this paper a novel lateral block size characterization method based on X‐ray diffractometry (XRD) is presented. The developed method based on scans of plans perpendicular to the surface visible from the edge of the sample and subconsequent numerical analysis based on Scherrer equation. In presented investigations as a reference sample bulk GaN substrate fabricated by AMMONO Ltd. was used. The GaN layers deposited on sapphire substrate were investigated as a case of study. Moreover, a method of analyzing the magnitude of the tilt and twist mosaicity based on the scans of rocking curves and reciprocal lattice maps (RLM) from the edge of sample is presented. As an example for this methodology highly mosaicited SiC crystal was used. Presented approach allows to directly determine the value of the angular deviation of mosaicity in a direction perpendicular and parallel to the sample surface.

Time-resolved X-ray diffraction study of the structural dynamics in an epitaxial ferroelectric thin Pb(Zr0.2Ti0.8)O3 film induced by sub-coercive fields

“…In order to increase the acquisition speed, ω scans through the RSM were recorded with a home-built detector made of a photomultiplier tube (Hamamatsu) and a fast scintillator with <1 ns response time, which collects an angular divergence of the diffracted x-rays of 0.9 • , which exceeds the width of the RSM in either angular direction by a factor of three. This detection geometry is often referred to as rocking curve, an established method to determine lattice plane spacings in mosaic crystals via Bragg's law [31][32][33]. The typical full-width-at-half-maximum (FWHM) of the rocking curves was 0.3 • .The X-ray signal is sent to a timecorrelated single photon counting system (PicoHarp 300), which allows reconstructing the rocking curves at different delays by synchronizing the detector trigger with the rising edge of the electrical pulse.…”