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1

Ultraviolet detectors based on ZnO films by thermal oxidation of Zn metallic films

100%

Zheng X., Li Q.

Open Physics

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2008

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vol. 6

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issue 2

351-355

EN

Metallic Zn films were deposited on glass substrates by electron-beam evaporation. ZnO films were synthesized by thermal oxidation of Zn metallic films in air. At the annealing temperature of 550 °C, ZnO nanowires appeared on the surface, which mainly result from the decrease of oxidation rate. A ZnO ultraviolet photodetector was fabricated based on a metal-semiconductor-metal planar structure. The detector showed a large UV photoresponse with an increase of two orders of magnitude. It is concluded that promising UV detectors can be obtained on ZnO films by thermal oxidation of Zn metallic films. The ways of performing spectral response measurements for polycrystalline ZnO films are also discussed.

2

Effect of Nitridation and Pre-Growth Annealing of the Sapphire Substrate on the Quality of Zinc Oxide Thin Films Grown by RF-Magnetron Sputtering

100%

Baseer Haider M.

Acta Physica Polonica A

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2017

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vol. 132

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issue 4

1325-1328

EN

ZnO has attracted much attention due to its wide bandgap (3.2 eV) and high exciton binding energy of 60 meV. These properties make ZnO a highly desirable material for high frequency devices that can work in harsh environment. We have grown ZnO thin films at different temperatures ranging from 100°C to 500°C. We have observed that surface roughness is first decreased with the increase in the growth temperature but then by further increasing the growth temperature beyond 300°C, results in increased surface roughness of the grown samples, whereas grain size of the samples increases with the increase in the growth temperature. Crystalline quality of the films is also improved with the increase in the growth temperature but then degrades by further increase beyond 200°C. We achieved the highest Hall mobility for the ZnO sample grown at 200°C. The optimum growth condition of ZnO thin films on sapphire (0001) in our RF/DC magnetron-sputtering unit were achieved for the films grown at 200°C. Subsequently, we performed pre-growth treatment to the sapphire substrate then grew ZnO films at 200°C. Pre-growth treatment involved heating the substrate at 500°C for about half an hour and then etching the sapphire surface with nitrogen plasma. We have observed that pre-growth heating and nitridation of the sapphire substrate results in bigger grain size whereas no improvement was observed in the crystallinity of the film.

3

Effects of mechanical activation on structure and photocatalytic properties of ZnO powders

88%

Gancheva M., Iordanova R., Dimitriev Y., Avdeev G., Iliev T.

Open Chemistry

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2013

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vol. 11

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issue 11

1780-1785

EN

Zinc oxide (ZnO) was mechanically activated in air using a planetary ball mill using varying milling speeds and time. The obtained samples were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and UV-Vis diffusion reflectance spectroscopy. The photocatalytic activity of the mechanically treated ZnO powders were investigated in the reaction of Malachite Green (MG) degradation in aqueous solution under UV-light irradiation. A decrease in the crystallite size (from 90 to 10 nm) accompanied by an increase of microstrains and lattice parameters were established applying different milling speeds. The agglomeration of the particles was observed by SEM analysis. The absorption spectra of the initial and mechanically activated ZnO samples show shifting of the band position from 360 to 330 nm, which can be related to decrease in the crystalline size. The ZnO powders activated at lower milling speeds (for shorter time intervals) exhibit highest photocatalytic activity. [...]

4

ZnO thin film as methane sensor

88%

Mitra P., Mukhopadhyay A. K.

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2007

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vol. 55

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issue 3

5

Investigation on the catalytic activity of doped low-percentage oxide catalysts Mn/ZnO obtained from oxalate precursor

75%

Donkova B., Milenova K., Mehandjiev D.

Open Chemistry

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2008

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vol. 6

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issue 1

115-124

EN

The precursors with a low manganese content ≤ 0.07% Mn were synthesized by spontaneous crystallization from Zn2+, Mn2+ and C2O42−-containing solutions. The initial ratio Zn2+:C2O42− = 1:1 and 1:2 influences the morphology and prevailing orientations of the crystallites in the oxalate samples. The presence of such small Mn content in the samples does not change the morphology or size of the crystals. The ZnO and Mn/ZnO oxides with manganese content from 0.51×10−2 to 15.1×10−2 Wt % are obtained after thermal decomposition of the oxalates. The oxides preserved the morphology of the precursors. The catalytic tests show that the pure ZnO has a poor activity for CO oxidation reaction. Its doping with Mn promotes the catalytic activity (up from twice to five times) in spite of the very low contents of the dopants. The observed increase of the activity depends on both dopant concentration and Zn2+:C2O42− ratio, probably due to the different mechanism of the manganese inclusion and different morphology of the oxides. The catalysts of the 1:2 series are more active in CO oxidation reaction. [...]

6

Growth and characterization of pulsed laser deposited ZnO thin films

75%

Vincze A., Bruncko J., Michalka M., Figura D.

Open Physics

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2007

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vol. 5

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issue 3

385-397

EN

One of the most important and promising materials from metal oxides is ZnO with specific properties for near UV emission and absorption optical devices. The properties of ZnO thin films strongly depend on the deposition method. Among them, pulsed laser deposition (PLD) plays an important role for preparing various kinds of ZnO films, e.g. doped, undoped, monocrystalline, and polycrystalline. Different approaches - ablation of sintered ZnO pellets or pure metallic Zn as target material are described. This contribution is comparing properties of ZnO thin films deposited from pure Zn target in oxygen atmosphere and those deposited from sintered ZnO target. There is a close connection between final thin film properties and PLD conditions. The surface properties of differently grown ZnO thin films are measured by secondary ion mass spectrometry (SIMS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Furthermore, different approaches - ablation of sintered ZnO pellet or pure metallic Zn as target materials are described. The main results characterize typical properties of ZnO films versus technological parameters are presented.

7

THE MORPHOLOGY AND STRUCTURE OF ZnO THIN FILMS DEPOSITED BY ALD METHOD

75%

Boryło P., Gołombek K., Matus K., Lukaszkowicz K.

Archives of Metallurgy and Materials

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2018

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vol. 63

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issue 1

8

Metal oxide particles catalyze photo-oxidation in environmental media

63%

Minelli C., Tantra R.

Nanomaterials and the Environment

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2013

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vol. 1

40-47

EN

Metal oxide particles in the submicron and nanometer range endow a wide range of consumer products with unique properties. The widespread use of such products raises concerns on potential toxicity of these materials to man and the environment. Besides their size, the photo-catalytic properties of metal oxide particles are of particular concern. By utilizing molecular probes with tailored optical properties, we investigated the photo-catalytic properties of seven TiO2 (anatase), ZnO and CeO2 manufactured particles in environmental media. Controlled experiments confirmed that the particles catalyzed photo-oxidation and photo-production of reactive oxygen species (ROS), while no ROS generation was observed when the ionic form of the materials was used in place of the particles. While affecting their aggregation and sedimentation, the type of media was not found to strongly influence the photo-catalytic behavior of the particles. Within the size range that was investigated, ZnO particles resulted in the highest production of ROS, while anatase particles possessed the highest oxidative ability. Possible explanations of such behavior are suggested.

Refine search results

Ultraviolet detectors based on ZnO films by thermal oxidation of Zn metallic films

Effect of Nitridation and Pre-Growth Annealing of the Sapphire Substrate on the Quality of Zinc Oxide Thin Films Grown by RF-Magnetron Sputtering

Effects of mechanical activation on structure and photocatalytic properties of ZnO powders

ZnO thin film as methane sensor

Investigation on the catalytic activity of doped low-percentage oxide catalysts Mn/ZnO obtained from oxalate precursor

Growth and characterization of pulsed laser deposited ZnO thin films

THE MORPHOLOGY AND STRUCTURE OF ZnO THIN FILMS DEPOSITED BY ALD METHOD

Metal oxide particles catalyze photo-oxidation in environmental media