High resolution X-ray diffraction, X-ray multiple diffraction and cathodoluminescence as combined tools for the characterization of substrates for epitaxy: the ZnO case

Abstract

The goal of this work is to show the capability of X-ray multiple diffraction (XRMD) to be used in combination with high resolution X-ray diffraction (HRXRD) and cathodoluminescence (CL) as an easy and simple methodology to determine structural and surface defect-related characteristics of samples that could be used as substrates for epitaxial growth. For this study ZnO {0001}-oriented samples have been used in view of their use as substrates for homoepitaxy. The miscut and bending of the samples have been analyzed by measuring the position of the X-ray diffraction peaks. The presence of multiple crystallographic domains and their characteristics have been studied by HRXRD (from the allowed (0002) reflection) and XRMD (from the forbidden (0001) and (0003) reflections) through Renninger scans and omega-scans. Cathodoluminescence adds to the previous structural characterization the possibility of obtaining significant information on surface and bulk defect-related optical properties by means of probe depth modulation. Thus, the combined methodology using HRXRD, XRMD and CL shows its ability to assess the structural and surface defect-related properties of substrates, allowing an easy detection of subtle structural and surface defects that can affect the ulterior use of these substrates in epitaxial growth.