X-ray characterization of innovative semiconductor crystals and study of their applications

Abstract

This thesis focuses on experimental work in which X-ray diffraction technique has been used to probe and study the properties of semiconductor crystals for applications in astrophysics and photovoltaics. For the purpose of diffracting high-energy photons for astrophysical observations through a Laue lens, X-ray diffraction has been applied to silicon and germanium curved crystals with the aim to study their structural deformation and diffraction properties. In the framework of “Laue project”, a thorough X-ray characterization has been carried out, allowing accurate adjustment of the experimental parameters for crystal fabrication and certification of its quality of diffraction properties prior to installation as optical element onto the lens. Main experimental results of X-ray diffraction obtained at ESRF are presented and highlight that crystals diffracted photons from 150 to 700 keV with efficiency peaking 95% at 150 keV for Si. With regard to photovoltaics, heteroepitaxial SiGe samples have been investigated by X-ray diffractometry for their usage as multi-junction solar cells