ZnO nanopencils were synthesized on a silicon wafer without catalysts at a low temperature of 550 ° C through a simple two-step pressure controlled thermal evaporation. Penholders were well-hexagonal faceted and the diameter of pen tips on the nanopencils was in the range of 20–30 nm. High-resolution transmission electron microscopy shows that the nanopencils were single crystals growing along the [0001] direction and the pen tips subtend a small angle with multiple surface perturbations. Field-emission measurements on the nanopencils show a low turn-on field of 3.7V∕μm at a current density of 10μA∕cm2. The emission current density reached 1.3mA∕cm2 at an applied field of 4.6V∕μm. The emission at the low field is attributed to the sharp tip and surface perturbations on the nanopencils.

ZnO single-crystalline nanowire-type nanostructures were synthesized on silicon by thermal chemical vapor deposition without catalysts through a two-step pressure-controlled vapor-reflected process at a low temperature of 550 °C where self-organized hexagonal crystalline or porous nanowire arrays were grown on nanorods. The nanowire diameter is around 20 nm and number of nanowires is selected by the nanorod size. Cathodoluminescence spectra exhibit strong green emissions, indicative of high oxygen-vacancy density, which sheds a light on further applications for multichannel nanoconductors in nanodevices.

Single-crystalline AlZnO nanomaterials were synthesized through a proposed alloy-evaporation deposition method at the low temperature of 550°C by thermal chemical vapor deposition. Transmission electron microscopy images show that AlZnO nanowires, or nanowire/nanotube junction structures, can be synthesized where the Al/ ͑Al+ Zn͒ atomic ratio is determined to be about 2.5 and 12 at. %, respectively, by electron energy loss spectrometry. Room-temperature cathodoluminescence measurements show that the AlZnO nanowires exhibit a strong ultraviolet emission, which shifts to a higher energy from 3.29 to 3.34 eV due to Al incorporation.

Diverse ZnO integrated nanostructures, constructed by epitaxial nanowalls and symmetric single-crystalline nanosheets, were successfully synthesized via a strain-assisted self-catalyzed process at a low temperature of 500°C. The nanostructures started with the growth of ZnO nanowires, nucleated on a rugged ZnO single-crystalline film via a strain-assisted self-catalyzed growth mechanism. The nanowalls were then formed by the interconnection of the nanowires. Finally, the nanosheets were grown from the edges of the nanowalls. The growth mechanisms were supported by direct experimental evidence. Room-temperature cathodoluminance spectra show a relatively strong and sharp ultraviolet emission as well as a weak and broad green emission. The integrated nanostructure may be applied to develop self-inclusive nanoelectronics.

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