Interface Analysis of MOCVD Grown GeTe/Sb₂Te₃ and Ge-Rich Ge-Sb-Te/Sb₂Te₃ Core-Shell Nanowires

Controlling material thickness and element interdiffusion at the interface is crucial for many applications of core-shell nanowires. Herein, we report the thickness-controlled and conformal growth of a Sb₂Te₃ shell over GeTe and Ge-rich Ge-Sb-Te core nanowires synthesized via metal-organic chemical vapor deposition (MOCVD), catalyzed by the Vapor-Liquid-Solid (VLS) mechanism. The thickness of the Sb₂Te₃ shell could be adjusted by controlling the growth time without altering the nanowire morphology. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were employed to examine the surface morphology and the structure of the nanowires. The study aims to investigate the interdiffusion, intactness, as well as the oxidation state of the core-shell nanowires. Angle-resolved X-ray photoelectron spectroscopy (XPS) was applied to investigate the surface chemistry of the nanowires. No elemental interdiffusion between the GeTe, Ge-rich Ge-Sb-Te cores, and Sb₂Te₃ shell of the nanowires was revealed. Chemical bonding between the core and the shell was observed.