Coherent X-ray scattering of crystalline order in metallic nanostructure containing Au and Sn

Abstract

In this thesis, coherent X-ray scattering and fundamental X-ray diffraction （XRD） techniques were employed to investigate the structural evolution, crystalline order, and domain dynamics in metallic nanostructure systems. In Chapter 1, Bragg coherent X- ray diffraction imaging （BCDI） combined with autocorrelation function （ACF） analysis was used to investigate the morphological evolution of Au nanocrystalline domains during in-situ annealing. A multi-domain anisotropic particle rearranged into a single- crystalline equilibrium structure, accompanied by a decrease of lattice tilt and strain distribution. In Chapter 2, the crystalline structure and morphology of Sn tips in VLS-grown Sn-ITO nanostructures were examined using BCDI and XRD. The crystallographic relationship among the Sn tip, ITO stem, and substrate was investigated with XRD. In particular, BCDI measurement of the Sn tip revealed a highly ordered single crystal with a droplet-like truncated geometry, together with its internal Bragg amplitude, strain distribution, and interface characteristics between ITO stem and substrate. As the next chapter 3, the thickness dependence of the order-disorder transition in Au5Sn thin films was investigated using three-dimensional XRD. As the thin film thick- ness decreased from bulk-like sample, the transition temperature decreased, while the thinnest film exhibited absent transitions. Furthermore, the order–disorder transition in the thin film was identified as a first order transition characterized by domain-scale structural evolution. Analysis of the Laue oscillations revealed that the transition occurred throughout the entire volume rather than within a localized regions. At last Chapter 4, the crystallization behavior and structural evolution of amor- phous Ga2O3 thin films on sapphire （0001） substrates investigated using synchrotron- based in-situ multimodal characterization techniques via solid phase epitaxy.