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Single Crystalline ZnO NanotubesMarch 17, 2007 The unique structures of nanotubes provide large surface areas for biological and chemical sensing. Nanotubes of nitrides and oxides offer unique properties unavailable from carbon nanotubes. These nanotubes are hydrophilic and offer better chances of functionalization for sensing and nanofluidic applications. Based on the theory of nucleation and the vapor-solid growth mechanisms, Associate Professor of Physics Yoke Khin Yap and his research group have gained atomic scale control on the nucleation and growth of ZnO nanotubes (ZnO NTs) on the top surfaces of ZnO nanorods (ZnO NRs). This technique did not involve the use of multiple processing steps or templates. A rapid cooling of the growth temperatures forced the ZnO growth species to confine their nucleation at the edges of the top surfaces of ZnO NRs. When the temperature is just right to do so and yet sufficient to sustain continuous growth along the c-axis of the wurzitic ZnO NRs, ZnO NTs can thus be grown. Experiments shows that ZnO NTs with single and multiple channels can be grown and that they are single crystalline as suggested by high-resolution transmission electron microscopy. These ZnO NTs maintained the structural, electronic, and photonic properties of bulk ZnO crystals as suggested by X-ray diffraction, Raman spectroscopy, and photoluminescence. These results might indicate a universal route to transform other NRs into NTs. This paper is published in Applied Physics Letters 90, 113108 (2007). Images of ZnO NTs are featured as the cover image of the March 12, 2007 issue. This paper is now highlighted at the front page of APL. Applied Physics Letters is ranked as the most highly cited journals in applied physics. Related Links |
