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ZnS nanowires with periodically alternating twins along the growth direction of wires have been synthesized via a thermal evaporation method. Structural characterizations reveal that both sphalerite (cubic) and wurtzite (hexagonal) phases coexist in the synthesized nanowires. The periodically twinned ZnS nanowires are formed through the vapor-solid mechanism. High quality of the nanowires is confirmed by the optical absorption and the photoluminescence observations combined with large ratio surface and interfaces induced by the twin modulations. The perfect crystal structure indicates their potential applications in nanoscience and nanotechnology. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) of anodic alumina membranes with different pore sizes is investigated in this paper. We observe that a small pore size leads to a decrease of photoluminescence intensity, an increase of the recombination lifetime, and a broadening of the emission band. The origin of the PL characteristics are discussed together with the decay measurement of the emission band. [ABSTRACT FROM AUTHOR]

Mn-doped ZnS nanobelts have been prepared through a thermal evaporation method starting with a mixture of acetylacetonates and H[sub 2]S at 900 °C. The nanobelts had a uniform single-crystal hexagonal wurtzite structure and grew along [001] direction. Undoped ZnS nanobelts and ZnMnS nanobelts with 1%, 3%, and 5% Mn so obtained have been characterized by x-ray diffraction, energy dispersive x-ray analysis, and photoluminescence (PL) spectra. PL measurements showed that the fluorescence efficiencies increased and the glow peaks shifted to longer wavelengths as the Mn-doped ratios increased, and the doping was found responsible for the changes in the defect-related emission of the ZnS nanobelts. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

S-doped ZnO nanowires with an average diameter of 80 nm and length up to several tens of micrometers were produced through a simple physical evaporation approach. The nanowires had a single-crystal hexagonal structure and grew along the [102] direction. Photoluminescence (PL) measurements showed that the doping of sulfur shifted the PL spectrum peak towards short wavelengths, and the doping quantity was found responsible for the different characteristics. [ABSTRACT FROM AUTHOR]

Monoclinic gallium oxide (β-Ga[sub 2]O[sub 3]) nanowires were synthesized by heat treating a composite material of GaAs and pre-evaporated Au at 1240 °C in dry oxygen atmosphere. The catalytic Au metal generated liquid nanoclusters that serve as reactive sites confining and directing the growth of β-Ga[sub 2]O[sub 3] nanowires during the vapor-liquid-solid growth process. The β-Ga[sub 2]O[sub 3] nanowires have diameters ranging from 20 to 50 nm and lengths of several micrometers. Photoluminescence measurement under excitation at 250 nm shows that the bulk β-Ga[sub 2]O[sub 3] nanowires have a stable blue emission at 475 nm and an ultraviolet emission at 330 nm, which may be related to the defects such as the oxygen vacancy and the gallium-oxygen vacancy pair. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Highly ordered TiO[sub 2] nanowire (TN) arrays were prepared in anodic alumina membranes (AAMs) by a sol-gel method. The TNs are single crystalline anatase phase with uniform diameters around 60 nm. At room temperature, photoluminescence (PL) measurements of the TN arrays show a visible broadband with three peaks, which are located at about 425, 465, and 525 nm that are attributed to self-trapped excitons, F, and F[sup +] centers, respectively. A model is also presented to explain the PL intensity drop-down of the TN arrays embedded in AAMs: the blue PL band of AAMs arises from the F[sup +] centers on the pore walls, and the TNs first form in the center area of the pores and then extend to the pore walls. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Large-scale of crystalline GaN nanowires (diameter∼50 nm) have been fabricated through chemical-vapor deposition in the nanochannels of the anodic alumina template. X-ray diffraction and selected area electron diffraction pattern investigations indicate that the nanowires are single crystal with hexagonal wurtzite structure. A typical scanning electron microscopy image and the energy dispersive x-ray spectroscopy results indicate that indium nanoparticles only act as catalyst in GaN nanowires growth. At room temperature, photoluminescence spectrum of the GaN nanowire arrays shows a visible broadband with three peaks, which are located at about 363, 442, and 544 nm. The light emission may be attributed to GaN band-edge emission, the existence of defects or surface states, and the interaction between the ordered GaN nanowires and anodic alumina membrane. The growth mechanism of crystalline GaN nanowires is discussed. The method makes it possible to synthesize other nitride nanowire arrays. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Ordered semiconductor In[sub 2]O[sub 3] nanowire arrays are uniformly assembled into hexagonally ordered nanochannels of anodic alumina membranes (AAMs) by electrodeposition and oxidizing methods. Their microstructures were characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. A blue-green photoluminescence (PL) band in the wavelength range of 300–650 nm was observed in the In[sub 2]O[sub 3]/AAM assembly system. The PL intensity and peak position depend on the annealing temperature, which is mainly attributed to the singly ionized oxygen vacancy in the In[sub 2]O[sub 3] nanowire array system. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Ordered semiconductor ZnO nanowire arrays embedded in anodic alumina membranes (AAM) were fabricated by generating alumina templates with nanochannels, electrodepositing Zn in them, and then oxidizing the Zn nanowire arrays. The polycrystalline ZnO nanowires with the diameters ranging from 15 to 90 nm were uniformly assembled into the hexagonally ordered nanochannels of the AAM. Photoluminescence (PL) measurements show a blue PL band in the wavelength range of 450-650 nm caused by the singly ionized oxygen vacancy in ZnO nanowires. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]