Two-Step Growth of Hexagonal-Shaped ZnO Nanowires and Nanorods and Their Properties

2007 ◽  
Vol 7 (12) ◽  
pp. 4522-4528 ◽  
Author(s):  
Ahmad Umar ◽  
S. H. Kim ◽  
J. H. Kim ◽  
Y. B. Hahn
Keyword(s):  
Hexagonal Phase ◽  
Green Emission ◽  
Zinc Powder ◽  
Zno Nanowires ◽  
Thermal Evaporation Method ◽  
Single Crystalline ◽  
Uv Emission ◽  
Nano Structures ◽  
Wurtzite Hexagonal Phase ◽  
Step Growth

Single-crystalline with perfect hexagonal-shaped ZnO nanowires and nanorods, possessing the Zn-terminated (0001) facets bounded with the six-crystallographic equivalent {0110} surfaces, have been grown on Au-coated silicon substrate via thermal evaporation method using the metallic zinc powder in presence of oxygen. The detailed structural analyses reveal that the obtained nano-structures are single-crystalline with the wurtzite hexagonal phase and are preferentially oriented in the c-axis, [0001] direction. Raman spectra exhibit a sharp and strong optical phonon E2 mode at 437 cm−1 further confirms the good crystal quality with wurtzite hexagonal crystal structure for the deposited products. The room-temperature photoluminescence (PL) spectra, for both the structures, showed a sharp and strong UV emission with a suppressed green emission, indicating the good optical properties for the as-grown nanostructures.

Low-Temperature Growth of Flower-Shaped UV-Emitting ZnO Nanostructures on Steel Alloy by Thermal Evaporation

2007 ◽  
Vol 7 (12) ◽  
pp. 4421-4427 ◽  
Author(s):  
Ahmad Umar ◽  
S. H. Kim ◽  
J. H. Kim ◽  
Y. K. Park ◽  
Y. B. Hahn
Keyword(s):  
Thermal Evaporation ◽  
Hexagonal Phase ◽  
Zinc Powder ◽  
Hexagonal Structure ◽  
Structural Defects ◽  
Metal Catalyst ◽  
Steel Alloy ◽  
Zno Nanostructures ◽  
Uv Emission ◽  
Wurtzite Hexagonal Phase

Flower-shaped ZnO nanostructures, containing the triangular-shaped petals (sharpened tips and wider bases) have been achieved by simple thermal evaporation of high purity metallic zinc powder in the presence of oxygen at 440 °C on steel alloy substrate without the use of metal catalyst or additives. Detailed structural studies confirm that the obtained flower-shaped nanostructures are single crystalline and possesses a wurtzite hexagonal structure, grown along the c-axis in the [0001] direction. Raman and room temperature photoluminescence analysis substantiate a wurtzite hexagonal phase with a good crystal quality and a strong UV emission at 378 nm, respectively, indicating few or no structural defects. Additionally, a detailed possible growth mechanism has also been discussed.

Hierarchical ZnO Nanostructures: Growth and Optical Properties

2008 ◽  
Vol 8 (12) ◽  
pp. 6355-6360
Author(s):  
Ahmad Umar ◽  
A. Al. Hajry ◽  
S. Al-Heniti ◽  
Y.-B. Hahn
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Hexagonal Phase ◽  
Hierarchical Structures ◽  
Zinc Powder ◽  
Zno Nanostructures ◽  
Hierarchical Nanostructures ◽  
Uv Emission ◽  
Wurtzite Hexagonal Phase

Growth of hierarchical ZnO nanostructures composed of ZnO nanoneedles have been achieved via simple thermal evaporation process by using metallic zinc powder in the presence of oxygen at low temperature of 460 °C on silicon substrate without the use of any kind of metal catalysts or additives. It is confirmed by detailed structural studies that the as-grown hierarchical nanostructures are single crystalline with a wurtzite hexagonal phase and nanoneedles of these structures are grown along the c-axis in the [0001] direction. The Raman-scattering analysis substantiates a wurtzite hexagonal phase with a good crystal quality for the as-grown products. Room-temperature photoluminescence (PL) exhibits a strong UV emission at 380 nm confirming the excellent optical properties of as-synthesized hierarchical structures. A plausible growth mechanism is also proposed to clearly understand the growth process of the synthesized structures.

Controllable Synthesis of ZnO Nanonails by Vapor-Solid Process: Growth Mechanism and Structural and Optical Properties

2006 ◽  
Vol 957 ◽  
Author(s):  
Ahmad Umar ◽  
Q. Ahsanul Haq ◽  
Sang Hoon Kim ◽  
Yeon Ho Im ◽  
Yoon Bong Hahn
Keyword(s):  
Optical Properties ◽  
Substrate Surface ◽  
Hexagonal Phase ◽  
Zinc Powder ◽  
Metal Catalyst ◽  
Single Crystalline ◽  
Morphological Studies ◽  
Wurtzite Hexagonal Phase ◽  
Photoluminescence Studies ◽  
Source Materials

ABSTRACTSingle-crystalline with good optical properties aligned ZnO nanonails were grown on steel alloy substrate without the use of metal catalyst or additives by the thermal evaporation process using high purity metallic zinc powder and oxygen as source materials for zinc and oxygen, respectively. Detailed morphological studies by FESEM revealed that the obtained nanonails are grown in a high density over the whole substrate surface and are exhibiting perfect hexagonal-shaped caps. The diameters of the nanonails at their tops and bases are ranges from 120∼160nm and 50∼70 nm, respectively. The detailed structural characterizations confirmed that the synthesized nanostructures are single-crystalline and grown along the c-axis direction. Raman scattering and room-temperature photoluminescence studies demonstrated the wurtzite hexagonal phase and good optical properties, respectively for the grown nanonails.

scholarly journals PHOTOLUMINESCENCE EMISSION OF Cu DOPED ZnS MICROSTRUCTURES SYNTHESIZED BY THERMAL EVAPORATION

2018 ◽  
Vol 34 (2) ◽  
Author(s):  
Nghia Nguyen Van
Keyword(s):  
Thermal Evaporation ◽  
Hexagonal Phase ◽  
Green Emission ◽  
Blue Shift ◽  
Xrd Analysis ◽  
Photoluminescence Excitation ◽  
Excitation Spectra ◽  
Thermal Evaporation Method ◽  
Photoluminescence Emission ◽  
Green Emission Band

Cu doped ZnS microstructures were prepared by the thermal evaporation method using ZnS powder and CuCl2.2H2O powder as precusor materials. The microstructures was characterized by using X-ray diffraction (XRD) analysis. The XRD studies indicated that there are two phases (ZnS and ZnO) at the undoped sample, but  most of the samples are only having wurtzite (hexagonal) phase of ZnS after doping. The photoluminescence emission and photoluminescence excitation of ZnS and Cu2+ doped ZnS microstructures have been studied. The photoluminescence excitation spectra of  ZnS microstructures is present around 374 nm. After doping of Cu2+ ion the absorption wavelength shifted towards the lower wavelength, this blue shift in the absorption edge is a measure of increased band gap. The emission spectrum of pure ZnS has a green emission band centred at around 520 nm. After doping with Cu2+ ion the luminescence centers were transferred to 516 nm and a strong blue peak at 440 nm appears. The reasons of these will be discussed in this paper.

PREPARATION OF SiO2 HIERARCHICAL NANOSTRUCTURE VIA CATALYST-FREE THERMAL EVAPORATION METHOD

NANO ◽  
2013 ◽  
Vol 08 (04) ◽  
pp. 1350043
Author(s):  
JUN MA ◽  
GONG-YI LI ◽  
XIAO-DONG LI ◽  
GANG PENG ◽  
YI-HE LI ◽  
...  
Keyword(s):  
Photoluminescence Spectrum ◽  
Thermal Evaporation ◽  
Green Emission ◽  
Average Diameter ◽  
Nitrogen Atmosphere ◽  
Thermal Evaporation Method ◽  
Evaporation Method ◽  
Hierarchical Nanostructure ◽  
Catalyst Free ◽  
Step Growth

A novel hierarchical nanostructure of SiO2 nanowires standing on SiO2 microwires was synthesized through a catalyst-free thermal evaporation method in nitrogen atmosphere. The SiO2 nanowires have an average diameter of 100 nm and length of 2 μm, while the diameter of the SiO2 microwires is around 10 μm and the length is hundreds of micrometers. The photoluminescence spectrum of the SiO2 hierarchical nanostructure shows stable blue and green emission at 442 nm and 533 nm, respectively. An oxygen-assisted three-step growth mechanism was suggested to interpret the growth of the SiO2 hierarchical nanostructure.

Abnormal blueshift of UV emission in single-crystalline ZnO nanowires

2009 ◽  
Vol 129 (9) ◽  
pp. 996-999 ◽  
Author(s):  
Dandan Wang ◽  
Jinghai Yang ◽  
Guozhong Xing ◽  
Lili Yang ◽  
Jihui Lang ◽  
...  
Keyword(s):  
Zno Nanowires ◽  
Single Crystalline ◽  
Uv Emission

Optical Properties of Zigzag Twinned Geometry of Zn2SnO4 Nanowires

2007 ◽  
Vol 7 (2) ◽  
pp. 486-489 ◽  
Author(s):  
Sathyaharish Jeedigunta ◽  
Manoj K. Singh ◽  
Ashok Kumar ◽  
M. Shamsuzzoha
Keyword(s):  
Green Emission ◽  
Average Diameter ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Photoluminescence Properties ◽  
Thermal Evaporation Method ◽  
Green Emission Band ◽  
Uv Emission ◽  
Transmission Electron ◽  
Weak Peak

High-density single-crystalline Zn2SnO4 nanowires have been successfully synthesized by using a simple thermal evaporation method by heating a mixture of ZnO and SnO2 nano powders. The products in general contain various geometries of wires, with an average diameter of 80–100 nm. These nanowires are ultra-long, up to 100 microns. The transmission electron microscopy study showed that these nanowires exhibited zigzag twinned geometry, and grow along the 〈111〉 direction. Low-temperature photoluminescence properties of the nanowires were measured, showing a strong green emission band at about 515 nm and a weak peak corresponding to UV emission at about 378 nm, which have not been reported before.

Growth of ZnO Nanowires by Vapour Solid Mechanism

2017 ◽  
Vol 268 ◽  
pp. 249-253
Author(s):  
N. Akhiruddin ◽  
Rosnita Muhammad ◽  
Yussof Wahab ◽  
Zuhairi Ibrahim
Keyword(s):  
Zinc Oxide ◽  
High Energy ◽  
Zinc Powder ◽  
Optical Quality ◽  
Zno Nanowires ◽  
Thermal Evaporation Method ◽  
Oxide Nanowires ◽  
Force Microscopy ◽  
Atomic Force ◽  
Excitonic Emission

The growth of zinc oxide nanowires is further investigated by thermal evaporation method and is discussed with respect to vapour-solid (V-S) growth mechanism. In this paper, ZnO nanowires were synthesized on glass substrate without the use of any catalyst with a constant flow of argon gas 1.36 psig and oxygen gas of 0.34 psig. Zinc powder of 99.99% purity is placed in a horizontal furnace and exposed to temperature of 600°C for 90 minutes. The surface morphology of the deposited zinc oxide is investigated by the atomic force microscopy (AFM) images and it was found that the deposited ZnO has a rough surface while field-emission scanning electron microscopy (FESEM) confirms the morphology of the ZnO nanowires. Photoluminescence (PL) spectra indicate that the optical quality of the deposited structure is potentially excellent with high energy excitonic emission close to the band edge which is assigned to the surface exciton in ZnO at 3.4eV.

Synthesis and Characterization of ZnO Nanowires Using a Simple PVD Approach without Catalysts

2005 ◽  
Vol 475-479 ◽  
pp. 3535-3538 ◽  
Author(s):  
Long Shan Wang ◽  
X. Zhang ◽  
Fan Hao Zeng
Keyword(s):  
Green Emission ◽  
Average Diameter ◽  
Zno Nanowires ◽  
Synthesis And Characterization ◽  
Uv Laser ◽  
Photoluminescence Properties ◽  
Uv Emission ◽  
Evaporation Source ◽  
Strong Green Emission

Two kinds of ZnO nanowires with different morphologies and characters were produced on Si (100) using a new PVD approach by heating and oxidizing Zn powders directly without any catalysts. The nanowires have an average diameter of 80nm (deposited at the evaporation source) and 30nm (deposited downstream of the evaporation source) respectively, and are evenly distributed over an area of > 20mm2. The two nanowires have complete different photoluminescence properties. One has a strong green emission (510nm) with a weak UV emission (380nm). The other has a strong and sharp UV emission (385nm), showing the capability for UV laser emitters.

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