Photoluminescence Properties of ZnO and ZnCdO Nanowires (original) (raw)
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Korean Journal of Chemical Engineering, 2006
Synthesis of ZnO nanowires was achieved on Si(100) substrate by the thermal evaporation of high purity metallic zinc powder without the use of any metal catalyst or additives. The diameter and length of the as-grown nanowires were in the range of 20–35 nm and few micrometers, respectively. The shapes and sizes of ZnO nanowires were dependent on the growth time. The high resolution transmission electron microscopy and selected area electron diffraction patterns indicated that the as-grown products are single crystalline with wurtzite hexagonal phase. Room temperature photoluminescence studies exhibited a strong UV emission and a suppressed green emission, confirming the good optical properties for the deposited nanowires.
Synthesis and Photoluminescence Studies on Zinc Oxide Nanowires
ASEAN Journal on Science and Technology for Development, 2017
Semiconductor single crystal ZnO nanowires have been successfully synthesized by a simple method based on thermal evaporation of ZnO powders mixed with graphite. Metallic catalysts, carrying gases, and vacuum conditions are not necessary. The x-ray diffraction (XRD) analysis shows that the ZnO nanowires are highly crystallized and have a typical wurtzite hexagonal structure with lattice constants a = 0.3246 nm and c = 0.5203 nm. The scanning electron microscopy (SEM) images of nanowires indicate that diameters of the ZnO nanowires normally range from 100 to 300 nm and their lengths are several tens of micrometers. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra of the nanowires were measured in the range of temperature from 15 K to the room temperature. Photoluminescence spectra at low temperatures exhibit a group of ultraviolet (UV) narrow peaks in the region 368 nm ~ 390 nm, and a blue-green very broad peak at 500 nm. Origin of the emission lines in PL spectr...
Photoluminescence properties of ZnO nanowire arrays fabricated on silicon substrate
2013 13th IEEE International Conference on Nanotechnology (IEEE-NANO 2013), 2013
Photoluminescence studies of zinc oxide nanowires produced by a carbo--thermal method on a nickel foil substrate are reported. Two types of as--grown samples: the first -containing only buffer film, and the secondcontaining both zinc oxide nanowires and buffer film grown in the same technological process, were investigated by means of the temperature-dependent photoluminescence. X-ray diffraction measurements of buffer film show that it is polycrystalline and is composed from wurtzite-type ZnO (main phase) and includes minority phases: rock salt type (Ni,Zn)O and hexagonal C3N4. The shape of the apparently monocrystalline nanowires is characterized by hexagonal section matching with the expectations of the hexagonal ZnO structure. The presence of LO-phonon replicas in photoluminescence spectra for the second sample is used as an argument for confirmation that ZnO nanowires are single crystalline. The method of growth of ZnO nanowires on nickel oxide opens perspectives to produce Zn1−xNixO diluted magnetic semiconductor nanowires.
Journal of Alloys and Compounds, 2009
ZnO nanowires were grown on Si(1 0 0) and Si(1 1 1) substrates by a simple physical deposition method in a conventional tube furnace without the use of any catalyst. The substrates were placed at different temperature zones. ZnO nanowires with different diameters were obtained at different substrate temperatures. Photoluminescence (PL) spectroscopy has been employed to study the optical properties of ZnO nanowires with average diameters ranging from 29 to 75 nm. The shapes of the photoluminescence curves are dependent on the temperature and orientation of substrates. The ultraviolet photoluminescence peak exhibited a blue-shift in position with a decrease in the diameter of nanowires. Large diameter nanowires tend to have more intense UV emission.
Synthesis and photoluminescence studies on ZnO nanowires
2004
ZnO nanowires were grown in gram quantities on graphite flakes (as collector) using the vapour transport and condensation approach. The yield, defined as the weight ratio of ZnO nanowires to the original graphite flakes, has been studied thoroughly by tuning the various growth parameters such as pressure and temperature inside the tube furnace, the amount of graphite powder in the original source, the source to collector ratio, etc. A yield as high as 200% has been achieved, equivalent to a 40% conversion of the ZnO powder in the original source. A study comparing the photoluminescence spectra of the ZnO nanowires grown on both graphite flakes and substrates with commercially available ZnO powder has been carried out.
Visible Photoluminescence of Ultrathin ZnO Nanowire at Room Temperature
Crystal Growth & Design, 2006
Zinc oxide (ZnO) nanowire (NW) was grown on a ZnO-buffered silicon substrate by a hydrothermal method in an aqueous solution that contained methenamine (C 6 H 12 N 4) and zinc nitrate hexahydrate (Zn(NO 3) 2 ‚6H 2 O). The concentration of the zinc nitrate is the main factor that governed the morphology of the NW. As the concentration was reduced gradually, the diameter of the NW became smaller, and an ultrathin (e10 nm) single crystal of ZnO NW emerged. The sample of ultrathin NW contains many dislocations and exhibits an unusual characteristic photoluminescence (PL) spectrum in the visible light region.
Synthesis and photoluminescence of ZnO nanowires/nanorods
Journal of Materials Science: Materials in Electronics, 2005
We report growth of ZnO nanowires on various substrates using a vapour phase transport method and show that the growth mechanism is vapour-liquid-solid growth. We present photoluminescence data for samples grown on a-plane sapphire at room and low temperatures indicating that the optical quality of these structures is potentially excellent, with intense emission and narrow bound exciton linewidths. The intensity decays rapidly with increasing temperature, indicating a strong temperature-activated non-radiative mechanism whose origin is unclear. We observe a high energy excitonic emission close to the band edge which we assign to the "surface" exciton in ZnO at ∼3.368 eV. This assignment is consistent with the large surface to volume ratio of the nanowire systems under consideration and also indicates that this large ratio has a significant effect on the luminescence even at low temperatures. These surface effects may also be responsible for the rapid decay of the luminescence with increasing temperature via a temperature-activated surface recombination. The nanowire systems appear to offer the prospect of extremely efficient excitonic emission for device applications, and we note that one of the important aspects of achieving this potential will be control of the surface effects via passivation or other means.
Optical properties and microstructure of 2.02-3.30 eV ZnCdO nanowires: Effect of thermal annealing
Applied Physics Letters, 2013
ZnCdO nanowires with up to 45% Cd are demonstrated showing room temperature photoluminescence (PL) down to 2.02 eV and a radiative efficiency similar to that of ZnO nanowires. Analysis of the microstructure in individual nanowires confirms the presence of a single wurtzite phase even at the highest Cd contents, with a homogeneous distribution of Cd both in the longitudinal and transverse directions. Thermal annealing at 550 C yields an overall improvement of the PL, which is blue-shifted as a result of the homogeneous decrease of Cd throughout the nanowire, but the single wurtzite structure is fully maintained. V
Luminescence studies of isolated ZnO nanowires grown by the vapour-liquid-solid method
physica status solidi (c), 2012
In this work we analysed, by means of Spectral Imaging Cathodoluminescence, the luminescence properties of individual ZnO nanowires (NWs) grown by chemical vapour deposition. The NWs show a general increase of the radiative recombination channels, and a decrease of the relative intensity of the visible band respect to the bound exciton emission, pointing to a high crystal quality. Local changes in the peak position and intensity of the near band edge were found by studying the luminescence of individual NWs, which have been ascribed to structural changes along them.
Superlattices and Microstructures, 2015
ZnO nanowires were synthesized via a low-temperature (90℃) hydrothermal route on glass substrates pre-deposited with a ZnO seed layer. The influence of different annealing ambient conditions (air or vacuum) on the structure, photoluminescence and photocatalytic activity of ZnO nanowires was investigated by Raman spectroscopy, X-ray diffraction, photoluminescence (PL) and photochemical reactions etc. It was found that there existed graphitic carbons on the surfaces of ZnO nanowires after vacuum annealing. The PL intensity of ZnO nanowires with the graphitic carbons was significantly reduced while the photocatalytic activity was enhanced, indicating that the graphitic carbons could decrease the recombination probability of photo-induced carriers.