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Photoluminescence Properties of ZnO Nanorods Prepared Under Low Temperature

Lang Jihui,Yang Jinghai,Li Changsheng,Han Qiang,Yang Lili,Wang Dandan,Gao Ming,Liu Xiaoyan,

半导体学报 , 2008,
Abstract: Zinc oxide (ZnO) nanorods are grown on ITO conducting glass with the chemical bath deposition (CBD) method.XRD,SEM,and PL are used to characterize the crystal structures,surface morphologies,and photoluminescence properties of ZnO nanorods.The X-ray measurement results show that the growth orientation of the as-prepared ZnO nanorods is (002).The SEM results show that the size of ZnO nanorods increases with the molar concentration of zinc nitrate,and the diameter and length of nanorods increases significantly through tuning the reaction time when the molar concentration is 0.1M.The photoluminescence measurements show that the all the samples have good photoluminescence behaviors.The crystallization of the samples increases with the molar concentration of zinc nitrate and the reaction time.
Photoluminescence and Structural Properties of ZnO Nanorods Growth by Assisted-Hydrothermal Method  [PDF]
S. López-Romero, M. García-H
World Journal of Condensed Matter Physics (WJCMP) , 2013, DOI: 10.4236/wjcmp.2013.33024

Semiconducting zinc oxide (ZnO) nanorods were obtained in bulk quantity by an hexamethylenetetramine (HMTA)-assisted hydrothermal method at low temperature (90°C) with methenamine ((CH3)6N4 as surfactant and catalyst and zinc nitrate Zn(NO3)2·6H2O as Zn source. The structure and phase of ZnO nanorods were studied using x-ray diffraction (XRD) and high resolution transmission electron microscopy techniques (HRTEM). The morphology of the nanostructures was studied by scanning electron microscope (SEM) method. The photoluminescence (PL) properties were investigated founding two emission bands under UV excitation.

Photoluminescence of spray pyrolysis deposited ZnO nanorods  [cached]
K?rber Erki,Raadik Taavi,Dedova Tatjana,Krustok Jüri
Nanoscale Research Letters , 2011,
Abstract: Photoluminescence of highly structured ZnO layers comprising well-shaped hexagonal rods is presented. The ZnO rods (length 500-1,000 nm, diameter 100-300 nm) were grown in air onto a preheated soda-lime glass (SGL) or ITO/SGL substrate by low-cost chemical spray pyrolysis method using zinc chloride precursor solutions and growth temperatures in the range of 450-550°C. We report the effect of the variation in deposition parameters (substrate type, growth temperature, spray rate, solvent type) on the photoluminescence properties of the spray-deposited ZnO nanorods. A dominant near band edge (NBE) emission is observed at 300 K and at 10 K. High-resolution photoluminescence measurements at 10 K reveal fine structure of the NBE band with the dominant peaks related to the bound exciton transitions. It is found that all studied technological parameters affect the excitonic photoluminescence in ZnO nanorods. PACS: 78.55.Et, 81.15.Rs, 61.46.Km
SiC Nanorods Grown on Electrospun Nanofibers Using Tb as Catalyst: Fabrication, Characterization, and Photoluminescence Properties
Zhou Jin-Yuan,Chen Zhi-Yong,Zhou Ming,Gao Xiu-Ping
Nanoscale Research Letters , 2009,
Abstract: Well-crystallizedβ-SiC nanorods grown on electrospun nanofibers were synthesized by carbothermal reduction of Tb doped SiO2(SiO2:Tb) nanofibers at 1,250 °C. The as-synthesized SiC nanorods were 100–300 nm in diameter and 2–3 μm in length. Scanning electron microscopy (SEM) results suggested that the growth of the SiC nanorods should be governed by vapor-liquid-solid (VLS) mechanism with Tb metal as catalyst. Tb(NO3)3particles on the surface of the electrospun nanofibers were decomposed at 500 °C and later reduced to the formation of Tb nanoclusters at 1,200 °C, and finally the formation of a Si–C–Tb ally droplet will stimulate the VLS growth at 1,250 °C. Microstructure of the nanorod was further investigated by transmission electron microscopy (TEM). It was found that SiC <111> is the preferred initial growth direction. The liquid droplet was identified to be Si86Tb14, which acted as effective catalyst. Strong green emissions were observed from the SiC nanorod samples. Four characteristic photoluminescence (PL) peaks of Tb ions were also identified.
Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines  [PDF]
Tamar Andelman,Yinyan Gong,Gertrude Neumark,Stephen O'Brien
Journal of Nanomaterials , 2007, DOI: 10.1155/2007/73824
Abstract: A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm) nanorods were synthesized from trihexylamine, and large diameter (50–80 nm) nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green) emission of the photoluminescence (PL) spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.
Growth and Photoluminescence of ZnO and Zn1-xMgxO Nanorods by High-pressure Pusled Laser Deposition  [PDF]
ZHANG Peng, WANG Pei-Ji, CAO Bing-Qiang
无机材料学报 , 2012, DOI: 10.3724/sp.j.1077.2012.12015
Abstract: The influence of the experimental parameters such as temperature, target, and thickness of catalyst layer on the growth of nanorods were systemically studied by a newly designed and home-built high-pressure pulsed laser deposition Zn1-xMgxO (PLD). The growth mechanism and photoluminescence properties of ZnO and Zn1-xMgxO nanorods were also investigated. It was found that c-orientated ZnO nanorod arrays grown on silicon substrate were obtained when the growth temperature was 925 nd the thickness of gold catalyst layer was 2 nm. It was also proved that growth temperature and catalyst layer thickness were both crucial for the diameter and growth density of ZnO nanorods. A combination of vapor-liquid-solid (VLS) and vapor-solid (VS) mechanism was proposed to describe the growth of ZnO nanorods by high-pressure PLD. Zn1-xMgxO nanorods and nanobelts with random orientation were grown by doping the ZnO target with MgO. The bandgap of ZnO was effectively expanded together with defect-related levels formation in the forbidden gap, which also induced enhancement of visible peak emission.
Enhancement of Photoluminescence Lifetime of ZnO Nanorods Making Use of Thiourea
Erdal S nmez,Kadem Meral
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/957035
Abstract: We have investigated correlation of photoluminescence lifetime between zinc oxide (ZnO) nanorods and thiourea-doped ZnO nanorods (tu: CH4N2S). Aqueous solutions of ZnO nanorods were deposited on glass substrate by using pneumatic spray pyrolysis technique. The as-prepared specimens were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and time-resolved photoluminescence spectroscopy (TRPL). The photoluminescence lifetime of ZnO nanorods and ZnO nanorods containing thiourea was determined as =1.56±0.05 ns (2=0.9) and =2.12±0.03 ns (2=1.0), respectively. The calculated lifetime values of ZnO nanorods revealed that the presence of thiourea in ZnO nanorods resulted in increasing the exciton lifetime. In addition to the optical quality of ZnO nanorods, their exciton lifetime is comparable to the longest lifetimes reported for ZnO nanorods. The structural improvement of ZnO nanorods, containing thiourea, was also elucidated by taking their SEM images which show the thinner and longer ZnO nanorods compared to those without thiourea.
Investigation on the fabrication of Ag-doped ZnO nanorods by hydrothermal method

Chen Xian-Mei,Wang Xiao-Xia,Gao Xiao-Yong,Zhao Xian-Wei,Liu Hong-Tao,Zhang Sa,

物理学报 , 2013,
Abstract: Ag-doped ZnO nanorods with different morphologies and optical properties are synthesized by hydrothermal method on the DC magnetron-sputtered Al-doped ZnO (AZO) seed layers. The influences of the molar ratio of Ag ions to Zn ions (RAg/Zn) and the AZO seed layer on the structural and optical properties of the Ag-doped ZnO nanorods are carefully studied by using X-ray diffractometry, scanning electron microscopy, spectrophotometry, EDS spectrum, etc. The changes in the microstructure and optical property of Ag-doped ZnO nanorods are closely related to the change in the average head-face dimension induced by Ag doping as RAg/Zn increases, owing to the different relative proportions of Ag ions doped in ZnO nanorods resulting from the different particle sizes and densities of the seed layers. The photoluminescence intensity in the visible region for the ZnO nanorods growing on the 15 min-sputtered AZO is stronger than that of the ZnO nanorods growing on the 10 min-sputtered AZO seed layer at the same RAg/Zn, which results from the increased defects in ZnO. More point defects caused by Ag doping are produced as RAg/Zn increases, resulting in the broadening of PL envelope in the visible region. The microstructure of pure ZnO nanorod is related to the seed layer thickness-related degree of crystallinity and particle size.
Effect of Different Seed Solutions on the Morphology and Electrooptical Properties of ZnO Nanorods  [PDF]
M. Kashif,U. Hashim,M. E. Ali,Syed M. Usman Ali,M. Rusop,Z. H. Ibupoto,Magnus Willander
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/452407
Abstract: The morphology and electrooptical properties of ZnO nanorods synthesized on monoethanolamine-based seed layer and KOH-based seed layer were compared. The seed solutions were prepared in monoethanolamine in 2-methoxyethanol and potassium hydroxide in methanol, respectively. Zinc acetate dihydrate was as a common precursor in both solutions. The nanorod-ZnOs were synthesized via the spin coating of two different seed solutions on silicon substrates followed by their hydrothermal growth. The scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), and Raman studies revealed that the ZnO nanorods obtained from monoethanolamine-based seed layer had fewer defects, better crystals, and better alignment than those realized via KOH-based seed layer. However, the current-voltage (I-V) characteristics demonstrated better conductivity of the ZnO nanorods obtained via KOH-based seed layer. The current measured in forward bias was 4?mA and 40?μA for ZnO-nanorods grown on KOH-based seed layer and monoethanolamine-based with the turn on voltage of approximately 1.5?V and 2.5?V, respectively, showing the feasibility of using both structures in optoelectric devices. 1. Introduction Zinc oxide (ZnO) which belongs to II–IV group of semiconducting materials is increasingly getting more and more research interests because of its attractive and fascinating properties such as approximately 3.37?eV of direct wide bandgap and about 60?meV of exciton binding energy. In fact, these properties are suitable for numerous applications in optoelectronic and biomedical devices. For examples micro- and nanostructures ZnO were successfully used in various sensing appliances such as UV sensors, biosensors (protein, DNA, and cancer cell detection) as well as gas sensors [1–5]. In the last few decades, ZnO-nanostructures with many fascinating forms such as nanorods, nano-flakes, nanorings, and nanoribbons, were synthesized [6–9]. To obtain these structures, various methods such as MOCVD, sol-gel, molecular beam epitaxy, thermal evaporation, and site-selective deposition techniques were documented [10–16]. Among these techniques, sol-gel methods have got huge interests because of their reduced growth temperature, reduced cost, and superior simplicity. However, a comparative study of ZnO nanorods synthesized on monoethanolamine-based seed layer and KOH-based seed layer using sol-gel method to realize nanorod-ZnOs has yet to be systematically reported. In this study, nanorod-ZnOs were synthesized on two different seeded substrates and their morphological,
Hydrothermal Growth of Vertically Aligned ZnO Nanorods Using a Biocomposite Seed Layer of ZnO Nanoparticles  [PDF]
Zafar Hussain Ibupoto,Kimleang Khun,Martin Eriksson,Mohammad AlSalhi,Muhammad Atif,Anees Ansari,Magnus Willander
Materials , 2013, DOI: 10.3390/ma6083584
Abstract: Well aligned ZnO nanorods have been prepared by a low temperature aqueous chemical growth method, using a biocomposite seed layer of ZnO nanoparticles prepared in starch and cellulose bio polymers. The effect of different concentrations of biocomposite seed layer on the alignment of ZnO nanorods has been investigated. ZnO nanorods grown on a gold-coated glass substrate have been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. These techniques have shown that the ZnO nanorods are well aligned and perpendicular to the substrate, and grown with a high density and uniformity on the substrate. Moreover, ZnO nanorods can be grown with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a dominant (002) peak in an XRD spectrum and possessed a high crystal quality. A photoluminescence (PL) spectroscopy study of the ZnO nanorods has revealed a conventional near band edge ultraviolet emission, along with emission in the visible part of the electromagnetic spectrum due to defect emission. This study provides an alternative method for the fabrication of well aligned ZnO nanorods. This method can be helpful in improving the performance of devices where alignment plays a significant role.
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