STM and STS characterization of ZnO nanorods

Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) techniques were used for the morphological and electronic characterization of zinc oxide nanorods. Well crystalline ZnO nanorods of about 200 nm mean diameter and up to 5.0 μm in length were synthesized by a modified hydrothermal technique at low temperature, using ethylenediamine as a soft surfactant. By means of STM we could detect the formation of prismatic hexagonal and non-prismatic rounded shape ZnO nanorods. Formation of aligned grain structures induced by strain relaxation in the nanorods were also observed. Using STS we could determine the band gap and deep level states related with the formation of oxygen vacancies in the nanostructures by a strain relaxation process.