Fabrication of core/shell Ge/SiO2 and Ge/CdS nanospheres

Core/shell nanospheres of Ge/SiO2 and Ge/CdS have been synthesized by a simple thermal evaporation method using Ge, SiO or Ge, CdS as source materials. The synthesized products were characterized in detail using scanning electron microscope, transmission electron microscope as well as energy dispersive X-ray spectrometer. This simple synthesis technique not only provides a technique to protect Ge nanocrystals from oxidation, to form core/shell composite spheres, but also opens a new route to prepare core/shell spheres of a variety of semiconducting materials, such as core/shell Ge/ZnS nanospheres, ZnS/SiO2 nanospheres, etc., by a judicious choice of source materials.