|
Zinc oxide (ZnO) with a wide band gap of 3.37 eV, and a large exciton binding energy of 60 mV at room temperature, is
one of the most important n-type semiconductor, that has potential applications in the area of short-wavelength optoelectronic
devices, gas sensors, solar cells, and field emitters. Some advanced nanodevices based on one-dimensional (1-D) ZnO
nanomaterials have been successfully demonstrated in the past few years. The types of substrate have a great influence on the
properties of ZnO nanostrctural devices. Semiconductor substrates such as Si and Al2O3 were widely used for the collection
or epitaxial growth of ZnO nanostructures, for metal substrate, Fe and Cu foil has also been used as substrate, there are few
reports on ZnO nanowires grown on Ti foil, Ti is an important electrode metal that ohmic contact can be appropriately
achieved, which is critical for semiconductor device application. Besides, both Ti and ZnO show good biocompatibility, it is
expected that ZnO nanowires/ Ti show good performance on bio-sensors. In this paper, 1-D ZnO nanostructures have been
successfully fabricated on the conductive Ti substrate via a vapor phase transport (VPT) method by carbothermal reduction of
ZnO and graphite powder mixture in a tube furnace at 850°C. The final products were characterized by means of field
emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), high-solution transmission electron microscope
(HRTEM) (equipped with selected area electron diffraction, SAED), and photoluminescence (PL) spectroscopy. FE SEM
results show that dense, ultra-long (>10μm), and locally aligned ZnO nanowire arrays were grown on the Ti foil. The
diameter of nanowires exhibits a wide range from 150 nm to about 500nm. Structural characterizations (XRD, SAED,
HRTEM) indicate the as synthesized nanostructures have a ZnO wurtzite structure and are perfect single crystalline without
any defects or impurities. The growth direction is [0001]. Optical property (PL spectrum) shows strong UV emission is
detected in our sample.
|
