Rapid synthesis of white-light emissive ZnO nanorods using microwave assisted method

2015 ◽  
Vol 29 (35n36) ◽  
pp. 1550238 ◽  
Author(s):  
M. Karimipour ◽  
A. Mohammad-Sadeghipour ◽  
M. Molaei ◽  
M. Khanzadeh
Keyword(s):  
Microwave Power ◽  
Surface Defects ◽  
Energy Gap ◽  
Defect Density ◽  
Average Length ◽  
Zno Nanorods ◽  
Blue Emission ◽  
Ammonium Hydroxide ◽  
Zno Nanowires ◽  
Zinc Blende

In this paper, firstly we have synthesized ZnO nanowires using zinc acetate, ethanol and ammonium hydroxide by a thermo-chemical method and then ZnO nanorods (NRs) have been prepared by microwave irradiation (MI) of an initial solution containing ZnO nanowires. X-ray diffraction (XRD) analysis showed the rare zinc-blende phase which grows on the surface of NRs and its crystallite size increases with the increase of microwave power. The average length and width of rods were observed several hundreds of nanometer and 80[Formula: see text]nm, respectively, from scanning electron microscope (SEM) analysis. Ultraviolet-visible (UV-vis) absorption spectroscopy indicates that a band tail forms due to MI, which has roughly 2[Formula: see text]eV energy gap. Photoluminescence (PL) spectroscopy indicated a blue emission and a white emission for ZnO nanowires and NRs, respectively. MI quenches the UV emission from ZnO NRs and enhances the surface defects’ emission. The resultant visible PL of the samples increases with the increase of microwave power that shows the growth of zinc-blende phase which has crucial effect on the defect density of NRs.

Zno Nanorod Synthesis via Controlled ZnO Seed Layer by Filtered Pulse Cathodic Vacuum Arc: Luminescence Enhancement

2013 ◽  
Vol 802 ◽  
pp. 1-6
Author(s):  
Anumut Deachana ◽  
Paul K. Chu ◽  
Dheerawan Boonyawan
Keyword(s):  
Seed Layer ◽  
Energy Gap ◽  
Defect Density ◽  
Zno Nanorods ◽  
Vacuum Arc ◽  
Zno Nanorod ◽  
Large Area ◽  
High Quality ◽  
Continuous Growth ◽  
Seed Layers

A simple synthesis route to high-quality ZnO nanorod is reported, utilizing ZnO thin films grown by Filtered Pulse Cathodic Vacuum Arc (FPCVA) deposition as seed layers and continuous growth by hydrothermal method. Depending upon the FPCVA deposited conditions, implanted voltages, thickness and annealing temperature of ZnO seed layer, the surface morphology of the ZnO nanorod on ZnO film was noticeably different. The average diameters of the nanorod on Al substrates varied from about 131.99 ± 23.87 to 418.17 ±75.50 nm. The grown ZnO nanorod showed a high crystallinity with energy gap of 3.37 eV and low defect density confirmed by UV/VIS Spectrometer and photoluminescence spectrum (PL). Large-area growth, quasi-aligned and high quality indicates that the ZnO nanorods produced have potential application in field emission and optoelectronic devices.

scholarly journals Photoluminescence Study of the Influence of Additive Ammonium Hydroxide in Hydrothermally Grown ZnO Nanowires

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
A. S. Dahiya ◽  
S. Boubenia ◽  
G. Franzo ◽  
G. Poulin-Vittrant ◽  
S. Mirabella ◽  
...  
Keyword(s):  
Ammonium Hydroxide ◽  
Zno Nanowires ◽  
Photoluminescence Study

scholarly journals Effects of surface defects on the mechanical properties of ZnO nanowires

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Aditi Roy ◽  
James Mead ◽  
Shiliang Wang ◽  
Han Huang
Keyword(s):  
Mechanical Properties ◽  
Surface Defects ◽  
Zno Nanowires

Alloys and Exotic Materials

2020 ◽  
pp. 197-236
Author(s):  
Vurgaftman Igor
Keyword(s):  
Entire Range ◽  
Energy Gap ◽  
Lattice Structure ◽  
Hexagonal Boron Nitride ◽  
Ternary Alloys ◽  
Optical Parameters ◽  
Dilute Nitrides ◽  
Zinc Blende ◽  
Wurtzite Lattice ◽  
The Common

The chapter describes how the band parameters of ternary and quaternary alloys can be interpolated over the entire range of compositions, and tabulate the non-vanishing bowing parameters for most of the common alloys with both zinc-blende and wurtzite lattice structure. It also describes ordering in some of the ternary alloys, and how ordering affects the energy gap. The band parameters of dilute nitrides, dilute bismides, and hexagonal boron nitride are also examined. Finally, the chapter presents schemes for interpolating the optical parameters of III–V alloys, i.e., the real and imaginary parts of the permittivity or dielectric function.

SYNTHESIS AND CHARACTERIZATION OF ZnO NANORODS AND NANOWIRES USING PVP AS CAPPING

2009 ◽  
Vol 08 (03) ◽  
pp. 285-287 ◽  
Author(s):  
M. ESKANDARI ◽  
V. AHMADI ◽  
Sh. AHMADI
Keyword(s):  
Solution Method ◽  
Zno Nanorods ◽  
Green Emission ◽  
Zno Nanowires ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Solution Method ◽  
Air Atmosphere ◽  
20 Nm

In this study, ZnO nanowires are synthesized via ZnO nanorods at low temperature by using zinc acetate dehydrate and polyvinylpyrrolidone as precursor and capping, respectively. We use chemical solution method for synthesis of ZnO nanowires. Samples are characterized by means of scanning electron microscopy and X-ray diffraction. First, the nanorods are prepared at 300°C temperature, and then they are put into the furnace under air atmosphere at 450°C for 2 h. It is observed that nanowires with 20 nm diameter are produced. Photoluminescence spectra of nanorods and nanowires are compared. It shows that intensity of ultraviolet peak in the nanowires decreases but in contrast the intensity of green emission part increases. This is because, the surface effects such as oxygen vacancies increase in the structures of ZnO .

Surface Defects Control for ZnO Nanorods Synthesized Through a Gas-Assisted Hydrothermal Process

2016 ◽  
Vol 46 (1) ◽  
pp. 432-438 ◽  
Author(s):  
Limin Zhao ◽  
Changhua Shu ◽  
Zhengfeng Jia ◽  
Changzheng Wang
Keyword(s):  
Surface Defects ◽  
Zno Nanorods ◽  
Hydrothermal Process

STM studies of Fermi-level pinning on the GaAs(001) surface

1993 ◽  
Vol 344 (1673) ◽  
pp. 533-543 ◽  
Keyword(s):  
Fermi Level ◽  
Valence Band ◽  
Surface Defects ◽  
Defect Density ◽  
Valence Band Maximum ◽  
Intrinsic Defect ◽  
Fermi Level Pinning ◽  
Donor States ◽  
P Type ◽  
Surface Donor

This paper reviews recent scanning tunnelling microsopy (STM) studies of Fermi-level pinning on the surface of both n- and p-type GaAs(001). The samples are all grown by molecular beam epitaxy and have a (2 x 4)/c(2 x 8) surface reconstruction. The STM has shown that on the surface of highly doped n-type GaAs(001) there is a high density of kinks in the dimer-vacancy rows of the (2 x 4) reconstruction. These kinks are found to be surface acceptors with approximately one electron per kink. The kinks form in exactly the required number to pin the Fermi-level of n-type GaAs(001) at an acceptor level close to mid gap, irrespective of doping level. The Fermi-level position is confirmed with tunnelling spectroscopy. No similar surface donor states are found on p-type GaAs(001). In this case Fermi-level pinning results from ‘intrinsic’ surface defects such as step edges. Since this intrinsic defect density is independent of doping, at high doping levels the Fermi-level on p-type GaAs(001) moves down in the band gap towards the valence band. Tunnelling spectroscopy on p-type GaAs(001) doped 10 19 cm -3 with Be shows the Fermi-level to be 150 mV above the valence band maximum

Synthesis of ZnO Nanowires by Pulsed Laser Deposition in Furnace

2005 ◽  
Vol 900 ◽  
Author(s):  
Kyung Ah Jeon ◽  
Hyo Jeong Son ◽  
Jong Hoon Kim ◽  
K. H. Yoo ◽  
Sang Yeol Lee
Keyword(s):  
Pulsed Laser Deposition ◽  
Deep Level ◽  
Average Length ◽  
Green Light ◽  
Pulsed Laser ◽  
Zno Nanowires ◽  
Laser Deposition ◽  
Near Band Edge ◽  
Vacuum Furnace ◽  
Sem Images

ABSTRACTZnO nanowires (NWs) were fabricated on Au coated sapphire (0001) substrates by using a pulsed laser deposition (PLD) system in vacuum furnace with a Q-switched Nd:YAG laser. ZnO NWs have various size and shape with a substrate position inside a furnace, and their morphologic construction is reproducible. Scanning electron microscopy (SEM) images indicate that the diameters of ZnO NWs ranged from 100 to 150 nm and the average length was greater than 3 μm. Room-temperature photoluminescence spectra of the NWs show the near band-edge emissions and the deep-level green light emissions. The formation mechanism of the NWs is discussed.

scholarly journals Microwave Synthesis of Zinc Oxide/Reduced Graphene Oxide Hybrid for Adsorption-Photocatalysis Application

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Fatin Saiha Omar ◽  
Huang Nay Ming ◽  
Syed Muhamad Hafiz ◽  
Lim Hong Ngee
Keyword(s):  
Zinc Oxide ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Average Length ◽  
Hexagonal Phase ◽  
Zno Nanorods ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Enhanced Adsorption ◽  
Xrd Patterns

This work reports on synthesis of zinc oxide/reduced graphene oxide (ZnO/rGO) nanocomposites in the presence of diethylenetriamine (DETA) via a facile microwave method. The X-ray diffraction (XRD) patterns of the nanocomposites correspond to the ZnO hexagonal phase wurtzite structure. The high-resolution transmission electron microscopy (HRTEM) images revealed that the ZnO nanorods, with an average length : diameter ratio of 10, were successfully deposited on the rGO sheets. Under the irradiation of sunlight, the nanocomposites showed enhanced adsorption-photocatalysis by more than twofold and photocurrent response by sixfold compared to the ZnO. The excellent photoactivity performance of the nanocomposites is contributed by smaller ZnO nanorod and the presence of rGO that acts as a photosensitizer by transferring electrons to the conduction band of ZnO within the nanocomposite during sunlight illumination.

A formalism for the indirect Auger effect. I

1976 ◽  
Vol 347 (1651) ◽  
pp. 547-564 ◽  
Keyword(s):  
Room Temperature ◽  
Auger Recombination ◽  
Impact Ionization ◽  
Energy Gap ◽  
Electron Collision ◽  
Recombination Coefficient ◽  
Recombination Rates ◽  
Zinc Blende ◽  
Auger Effect ◽  
Ionization Rates

A general formalism has been developed for the calculation of band-band Auger recombination and impact ionization rates in diamond and zinc blende type structures. The energy gap involved in the transition must be of order 1eV or greater, at room temperature, for direct gaps but is arbi­trary for indirect gaps. A recombination coefficient of 28.1 x 10 -32 cm 6 s -1 for GaP (hole-hole-electron collision) has been obtained in reasonable agreement with experiment. The formalism gives better theoretical values for Ge and Si than so far available. This has tended to reduce the recombination rates expected theoretically.

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