Iridium dioxide (IrO 2 ) nanorods with pointed tips have been grown on Si(100) and transition-metal-coated-Si(100) substrates, via metal-organic chemical vapor deposition (MOCVD), using (MeCp)Ir(COD) as the source reagent. The as-deposited nanorods were characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). FESEM micrographs revealed that the majority of the nanorods are a wedge shape in cross section and converge at top; occasionally several of them pack into a column of a spiral tip. The vertical alignment and packing density are significantly improved by prior deposition of a thin layer of Ti on Si. TEM and XRD results indicate that the sputtered Ti thin layer erects the nanorods in the c-axis direction. XPS spectra show that iridium in IrO 2 nanorods also exist in a higher oxidation state.

We report on the preparation and field-emission properties of vertically aligned conductive IrO2 nanorods. The unique geometrical features of IrO2 nanorods, including nanosized structure and self-assembled sharp tip, exhibit a strong effect on field enhancement (β∼40 000), which result in a low threshold field (Eth∼0.7 V/μm) defined at the beginning of emission. A low turn-on field for driving a current of 10 μA/cm2 is about 5.6 V/μm, which is comparable with the carbon nanotube, diamond, and amorphous carbon. The potential of using IrO2 nanorods as an emitter material has been demonstrated.

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Nanotechnology V 1505Growth and Characterization of Iridium Dioxide Nanorods. -IrO 2 nanorods are grown on Si(100) substrates by metalorganic chemical vapor deposition using (Me-Cp)Ir(cod) as source (10-60 Torr O2, 350°C). The samples are characterized by FESEM, TEM, Raman spectroscopy, and XPS. IrO2 is a candidate material for field emission cathodes of vacuum microelectronic devices and field emission displays owing to its low surface work function. Apparently, IrO 2 nanometer-sized tips will be particularly appealing in manufacturing field emitters. -(CHEN, R. S.; HUANG*, Y. S.; LIANG, Y. M.; TSAI, D. S.; TIONG, K. K.; J.