Highly facetted metallic zinc nanocrystals fabricated by thermal evaporation

We report the fabrication of highly facetted, hexagonal shaped metallic Zn nanocrystals by a simple catalyst-free thermal evaporation technique on Si (001) substrate using Zn pellets as source material. The Zn nanocrystals were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The size of the crystals is of the order of 100 nm and they are highly facetted along {0001} and {101¯0} planes. SAD analyses revealed the possibility of the presence of a thin ZnO layer on the surface of the as-deposited Zn nanocrystals. Formation of an epitaxial core-shell structure due to surface oxidation was further confirmed by exposing the Zn nanocrystals to air, which led to the formation of crystalline ZnO having same crystallographic orientation as that of the underlying metallic Zn.