Coaxial Nanorod Research Articles

Observation of Single-Electron Transport in a Zn0.8Mg0.2O/ZnO Coaxial Heterostructure Nanorod

Observation of Single-Electron Transport in a Zn0.8Mg0.2O/ZnO Coaxial Heterostructure Nanorod

Morphogenesis of Branched Coaxial Nanorods Formed in Supercritical Carbon Dioxide

Fe3O4/a-C branched and multibranched coaxial nanowires with a diameter around 40 nm were synthesized by pyrolysis of ferrocene in supercritical CO2 at 450 °C. The single-crystal Fe3O4 cores of the ...

Near ultraviolet light emitting diode composed of n-GaN∕ZnO coaxial nanorod heterostructures on a p-GaN layer

The authors report on the fabrication and characteristics of near ultraviolet nanorod light emitting diodes (LEDs) composed of n-GaN∕ZnO nanorod heterostructures on p-GaN substrates. The nanorod LEDs consist of the vertically aligned n-GaN∕ZnO coaxial nanorod arrays grown on a p-GaN substrate. The LEDs demonstrated strong near ultraviolet emission at room temperature. The nanorod LEDs were turned on a forward-bias voltage of 5V, and exhibited a large light emitting area. From electroluminescent spectra, dominant emission peaks were observed at 2.96 and 3.24eV for an applied current of 2mA. The origins of the strong and large area light emission are also discussed in terms of enhanced carrier injection from n-GaN nanostructures to p-GaN substrates.

Heteroepitaxy of One Dimensional (1-D) Ga2O3-GaN Core-Shell Nanorods

1-D Ga2O3-GaN core-shell nanorods were successfully fabricated by two-step synthesis processes. The Ga2O3 nanorods were synthesized by the reaction of Ga with SiO2 at 600{degree sign}C. Subsequently, one dimensional Ga2O3-GaN core-shell nanorods were successfully achieved by nitrifying the as-synthesized Ga2O3 nanorods under ammonia ambient at 700{degree sign}C for 6 hours. The field-emission scanning electron microscope (FESEM, JSM- 6500F), X-ray spectrometer (SHINMADZU), and the field-emission transmission electron microscope (FETEM, JEM-3000F) were utilized to investigate the morphologies, crystal structures, and compositions of nanorods in detail, respectively. Furthermore, optical investigation of Ga2O3-GaN coaxial nanorods heterostructures was carried out by photoluminescence (PL) measurements in present study.

Coaxial Nanorods of MgO Core with Si Shell Layers

This article demonstrates an approach to the synthesis of MgO/Si core-shell nanorods. The Si shell was close to amorphous, whereas the MgO core was crystalline with a cubic structure. The PL of the Si-coated products under excitation at 325 nm exhibited a visible light emission, which was almost identical to that of the uncoated ones.

Fabrication and photoluminescent characteristics of ZnO∕Mg0.2Zn0.8O coaxial nanorod single quantum well structures

The authors report on fabrication and photoluminescent (PL) properties of ZnO∕Mg0.2Zn0.8O coaxial nanorod quantum structures with various quantum well and barrier layer thicknesses. Employing catalyst-free metal-organic vapor-phase epitaxy, coaxial nanorod single quantum well structures were fabricated by the alternate heteroepitaxial growth of ZnO and Mg0.2Zn0.8O layers over the entire surfaces of the ZnO nanorods with fine thickness controls of the layers. The quantum confinement effect of carriers in coaxial nanorod quantum structures depends on the Mg0.2Zn0.8O quantum barrier layer thickness as well as the thickness of the ZnO quantum well layer. The temperature-dependent PL characteristics of the coaxial nanorod quantum structures are also discussed.

Enhanced Secondary Electron Emission from Group III Nitride/ZnO Coaxial Nanorod Heterostructures

Needle work: AlN/ZnO and GaN/ZnO coaxial nanoneedle heterostructures (see TEM image) have a higher secondary electron emission (SEE) yield (σ) than thin films of AlN and GaN deposited on Si substrates. The dependence of the SEE on the incidence angle of the beam indicates that these heterostructures do not follow the power law. The σ value of the heterostructures is enhanced by the inherited nanostructure from the ZnO nanoneedle template.

Local structure around Ga in ultrafine GaN∕ZnO coaxial nanorod heterostructures

The structure of tubular GaN coaxially grown on ZnO nanorods with thickness of 6–12nm was investigated using x-ray absorption fine structure (XAFS) at the Ga K edge. The XAFS measurements revealed that the GaN had a distorted-wurtzite structure, and that there were more distortions in the bond length of Ga–Ga pairs than in Ga–N pairs. However, no extra disorders were observed in any of the pairs. These results strongly suggest that Ga atoms first bonded to the ZnO template. Unlike other techniques, the XAFS determines structure around a selected species atom in nano-heterostructures.

Fabrication and Photoluminescent Properties of Heteroepitaxial ZnO/Zn0.8Mg0.2O Coaxial Nanorod Heterostructures

ZnO/Zn0.8Mg0.2O coaxial nanorod heterostructures were prepared by employing catalyst-free metal-organic vapor-phase epitaxy, and their structural and photoluminescent (PL) properties were investigated using transmission electron microscopy (TEM) and temperature-dependent PL spectroscopy. TEM images show that ZnO/Zn0.8Mg0.2O layers were epitaxially grown on the entire surfaces of the ZnO nanorods and the ZnO nanorod diameters as a core material were as small as 9 +/- 2 nm. A dominant PL peak was observed at 3.316 eV, from room-temperature PL spectra of ZnO/Zn0.8Mg0.2O coaxial nanorod heterostructures with ZnO core diameters of 9 nm, indicating a PL blue shift of 30 meV, which resulted from a quantum confinement effect along the radial direction in ZnO nanorods. Furthermore, temperature-dependent PL properties of the coaxial nanorod heterostructures were investigated, showing much higher PL intensity for the coaxial nanorod heterostructures than that of bare ZnO nanorods at room temperature. The origin of the enhanced PL intensity and reduced thermal quenching for the coaxial nanorod heterostructures is also discussed.

Modification of SiC based nanorods via a hydrogenated annealing process

We present a novel and simple method to modify silicon carbide nanorods coated in quartz by annealing in an ammonia atmosphere. The process allows the coaxial nanorod to be restructured such that the core becomes quartz with a thick silicon carbide sheath. The nanorods were analysed using bulk sensitive EELS and Raman spectroscopy and on a local scale using TEM imaging and spectroscopy.

Heteroepitaxal fabrication and structural characterizations of ultrafine GaN/ZnO coaxial nanorod heterostructures

We report on heteroepitaxial fabrication and structural characterizations of ultrafine GaN/ZnO coaxial nanorod heterostructures. The coaxial nanorod heterostructures were fabricated by epitaxial growth of a GaN layer on ultrafine ZnO nanorods. Epitaxial growth and precise control of GaN overlayer thickness were obtained by low pressure metalorganic vapor-phase epitaxy. ZnO nanorods grown on Si and sapphire substrates using catalyst-free metalorganic chemical vapor deposition exhibited diameters as small as 7 nm. Furthermore, structural properties of the coaxial nanorod heterostructures were investigated using both synchrotron-radiation x-ray diffraction and high resolution transmission electron microscopy.