Various shaped and sized Ge nanostructures were obtained by reducing GeO2 powder under a H2 atmosphere in a high-temperature tubular furnace. At a high depositing temperature region, crystalline Ge film was epitaxially grown on a silicon substrate. Jellyfish-like Ge/SiO2NWs composite structures were obtained next to germanium epitaxial film grown by Ge-catalyzed vapor–liquid–solid phase segregation mechanism. In addition, at the lower depositing temperature zones, Ge nanowires with various morphologies were formed owing to the temperature and concentration gradient by oxide-assisted vapor–solid mechanism and Ostwald ripening.
