پودر نانوکریستالین ZnO سنتز شده با روش رسوب تبخیر بخار شیمیایی فراصوتی

ZnO nanocrystalline powder synthesized by

ultrasonic mist-chemical vapour deposition

پودر نانوکریستالین ZnO سنتز شده با روش رسوب تبخیر بخار شیمیایی فراصوتی

ABSTRACT

In this paper, we report on the synthesis and characterization of ZnO nanocrystalline powder grown by ultrasonic mist-chemical vapour deposition (UM-CVD) which is a promising method for large-area deposition at low temperatures taking into account of its simplicity, inexpensiveness and safety. The morphology and crystallite size of the ZnO nanopowder characterized by FESEM and TEM revealed that the powder consisted of the mixture of nanoparticles with particle size of 50–100 nm. The XRD results indicated that the synthesized ZnO powder had the pure wurtzite structure with lattice parameters a and c of 3.244 and 5.297 nm, and c/a ratio of 1.6, respectively. High temperature XRD studies of ZnO nanopowder showed that the crystallite size increased with increasing temperature with a systematic shift in peak positions towards lower 2h values due to change in lattice parameters. Temperature dependence of the lattice constants shows linear increase in their values. Diffraction patterns of ZnO nanopowder obtained from TEM were also in agreement with the XRD results. The synthesized powder exhibited the estimated direct band gap (Eg) of 3.43 eV. The optical band gap calculated from Tauc’s relation and the band gap calculated from the particle size inferred from XRD were in agreement with each other.  2007 Elsevier B.V. All rights reserved.

 

سنتز و خواص اپتیکی فیلم‌های متخلخل نانوخوشه‌ای ZnO

Synthesis and optical properties of ZnO nanocluster porous

films deposited by modified SILAR method

سنتز و خواص اپتیکی فیلم‌های متخلخل نانوخوشه‌ای ZnO نشانده شده

توسط روش SILAR اصلاح شده

ABSTRACT

possessing wide band gap and large exciton binding energy. The recent discovery of ultraviolet-luminescence at room temperature for ZnO nanomaterial has stimulated great researching interest for its potential applications in various photoelectric devices [1]. ZnO nanocluster film belongs to a new class of ZnO-based photoelectric material. The quantum confinement and the surface state or other in-gap states in ZnO nanocluster could exert strong influence on its electronic state and optical properties [2], thus making it more promising for the production of optical devices. Therefore, the investigation on the optical properties of ZnO nanocluster films is of both fundamental interest and technological importance.

 

سنتز نانو ساختار ZnO با روش رسوب حمام شیمیایی

Synthesis and characterization of ZnO nanostructures using

modified chemical bath deposition method

سنتز و ویژگی های نانو ساختار ZnO با روش رسوب حمام شیمیایی اصلاح شده

ABSTRACT

ZnO thin films were deposited using a simple, convenient and an inexpensive modified chemical bath method along with subsequent air annealing. There action mechanism for the growth of the ZnO nanostructure after theair annealing is also discussed. SEM observations reveal the formation of flower like nanostructures that are composed of leaf-like petals of thin nanosheets. The annealed ZnO nanostructures grow with the hexagonal crystalstructure. The ZnO nanostructure exhibits a blue shift in its optical absorption spectrum. The room temperature photo luminescence study reveals UV emission peaks due to near band edge emissions along withd efect related blue and green emission peaks.

 

ویژگی های بصری و ساختاری نوار نازک ZNO با روش اسپاترینگ

Structural and optical characterization of ZnO thin films

for optoelectronic device applications by RF sputtering technique

ویژگی های بصری و ساختاری نوار نازک ZNO برای کاربردهای دستگاه آپتوالکترونیک

با روش اسپاترینگ RF

ABSTRACT

This work reports structural and optical study of ZnO thin films grown over p-type silicon (Si) and glass substrates by RF magnetron sputtering technique. Surface morphological and optical properties of thin film have been studied using X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX), ellipsometry and photoluminescence (PL) spectroscopy. Strong diffraction peak (002) obtained from XRD spectra of ZnO thin film indicates a preferential growth of single crystalline thin film along the c-axis oriented phase of hexagonal wurtzite structure. Surface morphological feature reveals uniform growth of undoped ZnO thin film over the substrate. Different important microstructural parameters for the film such as grain size, lattice parameters, defect density, stress and strain have been obtained. Optical properties such as transmittance, reflectance, absorption coefficient, refractive index and dielectric constant for a spectral range of 300–800 nm have been evaluated. A good optical transmittance of 83–92% has been observed for visible region, and the optical bandgap of ZnO films was found to be 3.23 eV. Energy Loss Function (ELF) and photoluminescence (PL) spectra for ZnO thin film has also been analyzed and reported.

 

سنتز هیدروترمال ZNO آراسته به کاهش اکسید گرافن

Hydrothermal synthesis of ZnO decorated reduced

graphene oxide: Understanding the mechanism of photocatalysis

سنتز هیدروترمال ZNO آراسته به کاهش اکسید گرافن : درک مکانیزم کاتالیز نوری

ABSTRACT

ZnO nanomaterials are grown in-situ on graphene oxide (GO) materials by a facile hydrothermal method at a temperature of 100
C. These ZnO–graphene composite materials display a strong and broad absorption in the visible region besides an intense UV absorption peak. The enhanced fluorescent quenching observed for the graphene hybrids compared to ZnO, indicates the photoinduced electron transfer between ZnO and graphene layers, which in-turn reduces the recombination of charge carriers. In order to understand the mechanism of improved photocatalytic properties, reagents such as a radical scavenger t-BuOH and a hole scavenger EDTA-2Na were employed. The addition of t-BuOH did not show any appreciable changes in the photo-degradation properties of the ZnO–graphene hybrids. However, the addition of EDTA-2Na significantly reduced the photocatalytic activities of the ZnO–graphene hybrids indicated that photo-generated holes are the main reactive oxidative species responsible for the photocatalytic reaction. It has been concluded that the excellent absorption range, efficient charge transportation and separation and high surface area make the ZnO–graphene hybrids a better photocatalyst under UV and visible light.

 

سنتز هیدروترمال و شناسایی لایه های ZnO با نانوساختارهای مختلف

Hydrothermal synthesis and characterization of

ZnO films with different nanostructures

سنتز هیدروترمال و شناسایی لایه های ZnO با نانوساختارهای مختلف

ABSTRACT

ZnO nanomaterials were grown on the F-doped SnO2 glass substrate by a two-step hydrothermal method [14]. Firstly, ZnO buffer layer was modified on FTO substrates by spin-coating. Secondly, hydrothermal method was employed to synthesize ZnO materials. ZnO buffer layer was obtained by the following procedure. Zinc acetate was dissolved in the mixed solution of ethanolamine and 2- methoxyethanol with a concentration of 0.75 M. The mixture was then agitated at 60 ◦C for 30 min to yield a homogeneous and stable colloid solution. The procedure was the same as Ref. [27]. After coated with the above colloid solution by spin-coating, FTO substrates were annealed at 300 ◦C to get ZnO buffer layer.

 

سنتز هیدروترمال نانو میله ی ZnO به کمک مایکروویو

Microwave-assisted hydrothermal synthesis and

characterization of ZnO nanorods

سنتز هیدروترمال به کمک مایکروویو و ویژگی های نانو میله ی ZnO

ABSTRACT

For the purpose of this study, the nanorods of zinc oxide were synthesized by rapid microwave-assisted hydrothermal route. The microstructure and surface morphology of the sensitized nanorods were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transimision electron microscope (TEM) . XRD results indicate that synthesized ZnO nanorods have wurtzite phase. The calculated value of the particle size using Debye Scherrer formula and Williamson Hall plot was found to be 20-28 nm and 35.3 nm, respectively. Low uniformity distribution of rod-like morphology (60-80 nm in diameter and average length about 250 nm) are seen in TEM micrographs. The optical parameters of the prepared ZnO nanorods have been calculated using Kubeleka-Munk. approach for the UV-vis diffuse reflectance spectrum.

 

سنتز نانو میله های ZnO با اندازه ی بزرگ با روش تبخیر حرارتی ساده

Synthesis of large size ZnO microrods by a simple way of

thermal evaporation

سنتز نانو میله های ZnO با اندازه ی بزرگ با روش تبخیر حرارتی ساده

ABSTRACT

Large sizeneedle-like ZnO microrods with diameters around 100 μm and length of up to2.5 mm have been achieved by asimple method of thermal evaporation of ZnO powder discs in the open air. Metallic catalysts and vacuum condition are not necessary. Both the micro-sized and nano-sized ZnO rods were grown vertically at different sites of the substrate. Theas-synthe sized micro rod sand nanorods are pure ZnO without any other element, and both of them consist of single crystalline cores with hexagonal cross sections.

 

سنتز دما پایین فیلم های نازک ZnO دوپ شده با سدیم و آلومینیوم

Low temperature synthesis wide optical band gap Al and

Al, Na) co-doped ZnO thin films)

سنتز دما پایین فیلم های نازک ZnO داپ همزمان شده با Al و Na

با باندگپ نوری گسترده

ABSTRACT

With a wide bandgap of 3.37 eV and a large exciton binding energy of 60meV at room temperature, zinc oxide (ZnO), like GaN, is considered as an important material for blue and ultra-violet optical devices. Its research interest arisen again since 1957, the New Jersey Zinc Company published a book entitled “Zinc Oxide Rediscovered” to promote the material’s “frontier” properties (such as semiconductor, luminescent, catalytic, ferrite, photoconductive, and photochemical properties) and illustrative applications. Recently, research focused mainly on fabrication of high quality single crystals and epitaxial layers, in order to fully realize ZnObased electronic and optoelectronic devices.

 

روش جدید سنتز لایه های نازک ZnO: ریزساختار، خواص الکتریکی و اپتیکی

New process for synthesis of ZnO thin films: Microstructural, optical

and electrical characterization

روش جدید سنتز لایه های نازک ZnO: ریزساختار، خواص الکتریکی و اپتیکی

ABSTRACT

Zinc oxide (ZnO) is an interesting wide-band-gap semiconductor material with a direct band gap of 3.36 eV [1] at room temperature and exciton binding energy of 60 meV. It has crystalline structure of the wurtzite type and the unit cell with the constants a = 3.24 ˚A and c = 5.19A˚ . Thin films of ZnO are utilized for a wide variety of electronic and opto-electronic applications, such as surface acoustic wave devices [4], transparent conducting electrodes [2], heat mirrors [3]. Nanoscale porous structures of ZnO with a high surface area find their application in chemical sensors [5] and dye-sensitised solar cells [6]. Various techniques have been used to deposit undoped and doped ZnO films on different substrates, including spray pyrolysis [7], organometallic chemical vapor deposition [8], pulsed laser deposition [9], sputtering [10], and sol–gel process [11].