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1

Effect of Substrate Temperature on the Structural and Optical Properties of Nanocrystalline Cadmium Selenide Thin Films Prepared by Electron Beam Evaporation Technique

100%

Suthan Kissinger N., Suthagar J., Saravana Kumar B., Balasubramaniam T., Perumal K.

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issue 4

623-628

EN

Cadmium selenide (CdSe) thin films on glass substrates were prepared by physical vapour deposition under vacuum using the electron beam evaporated technique for different substrate temperatures: room temperature, 100, 200, 300°C, respectively. X-ray diffraction analysis indicates that the films are polycrystalline, having hexagonal (wurtzite) structure irrespective of their substrate temperature. All the films show most preferred orientation along (0 0 2) plane parallel to the substrates. The microstructural parameters such as particle size, stress, strain and dislocation density were calculated. The grain size of deposited CdSe films is small and is within the range of 18 to 42 nm. The optical absorption spectra of electrom beam deposited CdSe films were studied in the wavelength region of 250-2500 nm. The energy gap (E_{g}) values (allowed direct transitions), calculated from the absorption spectra, ranged between 1.77 and 1.92 eV. The surface morphological quality of electron beam evaporated CdSe films were analyzed by scanning electron microscopy and atomic force microscopy.

2

Morphological Changes and Enhancement of Ultraviolet Emission by Subsequent Thermal Treatment of Ga-Doped ZnO Nanostructures

100%

Manzoor U.

Acta Physica Polonica A

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2015

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vol. 127

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issue 4

910-913

EN

ZnO nanostructures doped with a high concentration of Gallium (Ga) were synthesized on a Si substrate by thermal evaporation. Subsequent heat treatments of selected nanostructures was done at 600°C, 700°C, 800°C and 900°C. Scanning electron microscope (SEM), X-Ray diffraction (XRD) and photoluminance (PL) studies was performed after every heat treatment. Systematic scanning electron microscope (SEM) studies suggest significant sublimation at 800°C. XRD results show that crystal quality was improved by annealing and phase separation may occur after high temperatures annealing. Ultraviolet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with heat treatment.

3

Surface Morphology, Structural and Optical Properties of MgO Films Obtained by Spray Pyrolysis Technique

100%

Diachenko O., Opanasuyk A., Kurbatov D., Opanasuyk N., Kononov O., Nam D., Cheong H.

Acta Physica Polonica A

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2016

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vol. 130

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issue 3

805-810

EN

X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy, UV-visible photometry, and photoluminescence measurements were used to investigate the surface morphology and structural and optical properties of MgO films. Magnesium oxide films deposited by the spray pyrolysis technique were studied. The substrate temperature was varied from T_{s} = 643 K to 693 K. Magnesium chloride hexahydrate (MgCl₂·6H₂O), dissolved in deionized water, was used as the precursor solution. It was established that the single phase films crystallize into a cubic structure with very fine crystallite size (about 2 nm). The optical band gaps of the samples were varied from 3.64 eV to 3.70 eV. Also, the films have a high level of transmittance of 90%. Photoluminescence spectra show the emission peaks at approximately 412 nm (3.00 eV) and 524 nm (2.38 eV). The peak with the energy of 3.00 eV is ascribed to holes trapped in magnesium ion vacancies acting as acceptors (F⁺ center). The broad emission peak at 524 nm is related to the presence of defects (F¯ centers) associated with oxygen ion vacancies.

4

Solubility and Segregation of Co in CdTe-Based Ternary and Quaternary Alloys

100%

Miotkowska S., Dynowska E., Miotkowski I., Alawadhi H., Lewicki A., Metcalf P., Ramdas A.

Acta Physica Polonica A

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2002

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vol. 101

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issue 5

735-742

EN

Single crystals of Cd_{1-x}Co_xTe and Cd_{1-x-y}Co_xMn_yTe are characterized with X-ray powder diffraction and electron microprobe to establish compositional dependence of the lattice parameters and deduce Co solubility limit. The experimental compositional profiles are examined on specimens taken from various locations of ingots along their longitudinal axes and compared with normal freezing distributions. The values of Co segregation coefficient are analyzed for both ternary and quaternary alloys in terms of normal freezing mode.

5

Raman Characterisation of Cd_{1-x}Zn_x Te Thick Polycrystalline Films Obtained by the Close-Spaced Sublimation

100%

Znamenshchykov Y., Kosyak V., Opanasyuk A., Dorda V., Fochuk P., Medvids A.

Acta Physica Polonica A

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2017

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vol. 132

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issue 4

1430-1435

EN

In this work, we studied the Raman spectra of thick polycrystalline Cd_{1-x}Zn_x Te (CZT) films with x ranged from 0.06 to 0.68. Additionally, the surface morphology and structural properties were studied in order to determine the crystalline quality of the samples. The Raman spectra had a two-mode behavior typical for CZT solid solution and showed CdTe- and ZnTe-like longitudinal and transverse optical modes. The relationship between the frequencies of CdTe- and ZnTe-related modes on x was studied. We observed the deviation of the compositional dependence of phonon mode frequencies for polycrystalline CZT films in comparison with a similar dependence for CZT single crystals. Such deviation was caused by the effect of structural defects in polycrystalline films on frequencies of vibrational modes. The values of excitation wavelength, which allow achieving of high signal-to-noise ratio on the Raman spectra of CZT films with different zinc concentration in the result of resonant enhancement of phonon modes intensities, were experimentally determined.

6

PVT-Grown Single Crystals of Cd_{1-x}Zn_{x}Te (x ≤ 0.25) and ZnTe as Substrates for Epitaxy

100%

Mycielski A., Szadkowski A., Łusakowska E., Kowalczyk L., Domagała J., Bąk-Misiuk J., Wilamowski Z., Witkowska B.

Acta Physica Polonica A

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1998

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vol. 94

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issue 3

441-445

EN

The process of growth of single crystals of Cd_{1-x}Zn_{x}Te (x ≤ 0.25) and ZnTe by physical vapour transport has been optimized and the twin-free single crystals with a very good crystal structure and low density of dislocations are grown as substrates for MBE and other techniques of epitaxy. Characterization of the crystals is described.

7

Properties of ZnO and ZnMnO Thin Films Obtained by Pulsed Laser Ablation

80%

Virt I., Hadzaman I., Bilyk I., Rudyi I., Kurilo I., Frugynskyi M., Potera P.

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issue 1

34-37

EN

The results of experimental investigation of structural and physical properties of ZnO and ZnMnO films are presented in this work. The films of ZnO and Zn_{1-x}Mn_{x}O of different thickness were obtained on Al_{2}O_{3}, glass, and KCl substrates in vacuum of 1 × 10^{-5} Torr by the pulsed laser deposition method. The samples were obtained under the substrate temperature 300-473 K. A thickness of films was in the range of 0.5-1 μm depending on the number of laser pulses. The structure of target bulk materials was investigated by X-ray diffraction method. A structure of laser deposited films was investigated by the transmission high-energy electron diffraction method. Electric resistivity was measured in the temperature range 77-450 K. The presence of two activation energies in the temperature range 300-330 K and 330-450 K is followed from the analysis of the films electrical resistivity. These activation energies correspond to two deep donor's energy levels. The shallow donor's level is connected with manganese presence. Optical transmission of ZnO and ZnMnO films deposited at various temperatures were investigated.

8

Epitaxial ZnO Films Grown at Low Temperature for Novel Electronic Application

80%

Wachnicki Ł., Dużyńska A., Domagala J., Witkowski B., Krajewski T., Przeździecka E., Guziewicz M., Wierzbicka A., Kopalko K., Figge S., Hommel D., Godlewski M., Guziewicz E.

Acta Physica Polonica A

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2011

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vol. 120

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issue 6A

A-7-A-10

EN

Monocrystalline films of zinc oxide were grown at 300C by atomic layer deposition. ZnO layers were grown on various substrates like ZnO bulk crystal, GaN, SiC and Al_2O_3. Electrical properties of the films depend on structural quality. Structural quality, surface morphology and optical properties of ZnO films were characterized using X-ray diffraction, scanning electron microscopy, and photoluminescence, respectively. High resolution X-ray diffraction spectra show that the rocking curve FWHM of the symmetrical 00.2 reflection equals to 0.058° and 0.009° for ZnO deposited on a gallium nitride template and a zinc oxide substrate, respectively. In low temperature photoluminescence sharp excitonic lines in the band-edge region with a FWHM equal to 4 meV, 5 meV and 6 meV, for zinc oxide deposited on gallium nitride, zinc oxide and sapphire substrate, respectively.

9

Model and Properties of Fullerene-Like and Wurtzite-Like ZnO and Zn(Cd)O Clusters

80%

Ovsiannikova L.

Acta Physica Polonica A

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2012

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vol. 122

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issue 6

1062-1064

EN

The electronic structure of the ground state of fullerene-like and wurtzite-like Zn_{n}O_{n} and Zn_{n - x}Cd_{x}O_{n} clusters has been investigated by computer physics methods. A relative evaluation of the stability and band gap width of clusters depending on the number of atoms in the cluster and its geometry has been performed. The model of a fullerene-like (ZnO)_{60} particle with a mixed sp^3/sp^2 type of bonds has been constructed. A (ZnO)_{12} cluster of T_{h} symmetry was taken as a base of the model. Within the framework of the B3LYP electron density hybrid functional method with a set of 3-21G(d) split valence basis functions, a numerical investigation of the influence of the incorporation of cadmium (33%) into the ZnO matrix on the electronic structure and the band gap width has been performed.

10

Characterization of n-ZnO/p-GaN Heterojunction for Optoelectronic Applications

80%

Wachnicki L., Gieraltowska S., Witkowski B., Figge S., Hommel D., Guziewicz E., Godlewski M.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

869-872

EN

An important feature of zinc oxide and gallium nitride materials are their similar physical properties. This allows to use them as a p-n junction materials for applications in optoelectronics. In earlier work we presented use of ZnO as a transparent contact to GaN, which may improve external efficiency of LED devices. In this work we discuss properties of a n-ZnO/p-GaN heterostructure and discuss its optimization. The heterostructure is investigated by us for possible applications, e.g. in a new generation of UV LEDs or UV light detectors.

11

Properties of ZnO and Zn(Cd)O Fullerene-Like Clusters with a Shell of Diamond-Like Structure with sp^{2}/sp^{3} Bonds

80%

Ovsiannikova L.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

862-864

EN

The structural, cohesive, and electronic properties of a fullerene-like (ZnO)_{60} cluster with a shell of diamond-like structure with sp^2/sp^3 bonds have been investigated in comparison with those of clusters differing in geometry and composed of the equal number of ZnO structural units (clusters of fullerene, onion, and coordination tetrahedron) within the framework of the electron density hybride functional method (B3LYP) with a set of 6-31G(d) split valence basis functions. The fullerene-like (ZnO)_{60} cluster is used as a model in an investigation of the change in the band-gap width (the decrease in the band-gap width is ≈ 0.2 eV) in the case of the substitution of Zn atoms by Cd atoms (20% of substitution) in the ZnO matrix in ZnCdO ternary structures.

12

The Investigation of the Cadmium Effect on Properties of ZnCdO Alloys Using Zn_{36-x}Cd_{x}O_{36} Clusters

80%

Ovsiannikova L.

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vol. 126

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issue 5

1090-1092

EN

The structural, cohesive, and electronic properties of a fullerene-like Zn_{n-x}Cd_{x}O_{n} (n=36) clusters have been investigated within the framework of the electron density hybride functional method (B3LYP) with a set of 3-21G(d) split valence basis functions. These clusters are used as a model in an investigation of the change in the band-gap width in the case of the substitution of Zn atoms by Cd atoms in the ZnO matrix in ZnCdO ternary structures. The presented investigations showed that a substitution of Zn atom to Cd (5.5, 11, 16.7, 22 and 33 at.% Cd) leads to reduction of cluster stability and monotonous decrease of energy gap (0.145, 0.259, 0.354, 0.436, 0.586 eV, accordingly).

13

CdSe/ZnSe Quantum Dots Formed by Low Temperature Epitaxy and In-Situ Annealing: Properties and Growth Optimization

80%

Mahapatra S., Schumacher C., Kiessling T., Astakhov G., Bass U., Ossau W., Geurts J., Brunner K.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

769-776

EN

The formation of CdSe/ZnSe quantum dots by a method combining a low temperature MBE growth of a CdSe layer and its subsequent in-situ annealing at temperatures between 280-340ºC has been studied. The thermal treatment results in a re-organization of the surface from a nearly two-dimensional layer to an ensemble of three-dimensional dot-like features. In this work we optimized the different growth and annealing parameters of this process and compared the properties of the resultant dots with those of dots grown by conventional MBE at 300ºC. It is demonstrated that the luminescence properties of the dots for both growth techniques are comparable but the areal density achieved by the in-situ annealing technique is an order of magnitude lower. From high resolution X-ray diffraction results, it could be established that no desorption takes place despite significantly long annealing duration. Beyond a nominal coverage of 3.5 ML CdSe, stacking faults are generated, leading to a gradual decrease in luminescence intensities and an overlap of pendellösung fringes in X-ray diffractograms.

14

High-Resolution X-Ray Diffraction Studies on MBE-Grown p-ZnTe/n-CdTe Heterojunctions for Solar Cell Applications

80%

Wichrowska K., Domagala J., Wosinski T., Chusnutdinow S., Karczewski G.

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vol. 126

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issue 5

1083-1086

EN

High-resolution X-ray diffractometer was used to study structural quality, lattice parameters and misfit strain in p-ZnTe/n-CdTe heterojunctions grown by the molecular-beam epitaxy technique on two different (001)-oriented substrates of GaAs and CdTe. The X-ray diffractometer results indicate that the CdTe layers, grown on lattice mismatched GaAs substrate, are partially relaxed, by the formation of misfit dislocations at the interface, and display residual vertical strain of the order of 10^{-4}. The presence of threading dislocations in the layers effectively limits the efficiency of solar energy conversion in the investigated heterojunctions. Homoepitaxially grown CdTe layers, of much better structural quality, display unexpected compressive strain in the layers and the relaxed lattice parameter larger than that of the substrate. Possible reasons for the formation of that unusual strain are discussed.

15

Enhancement of the Ultraviolet Luminescence Intensity from Cd-Doped ZnO Films Caused by Exciton Binding

80%

Shtepliuk I., Lashkarev G., Khyzhun O., Kowalski B., Reszka A., Khomyak V., Lazorenko V., Timofeeva I.

Acta Physica Polonica A

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2011

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vol. 120

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issue 5

914-917

EN

ZnO films doped with the cadmium (0.4-0.6%) were grown on crystalline sapphire c-Al_2O_3 substrates applying radiofrequency magnetron sputtering at the temperature of 400°C in Ar-O_2 atmosphere. The as-grown films were investigated in detail using X-ray diffraction, X-ray photoelectron spectroscopy, and cathodoluminescence spectra. The X-ray diffraction analysis revealed that the films possess a hexagonal wurtzite-type structure with the dominant crystallite orientation along the c axis. It was found that the small concentration of the cadmium significantly enhances the ultraviolet emission associated with excitonic transitions. We suggest that this enhancement effect mainly results from appearance of the cadmium isoelectronic traps, which may bind an exciton, thereby increasing the probability of radiation recombination. The effect of Cd isoelectronic impurity on structural and luminescent properties of ZnO films is discussed.

16

ZnO Nanorods on Nanofibrous ZnO Seed Layers by Hydrothermal Method and Their Annealing Effects

80%

Yim K., Jeon S., Kim M., Kim S., Nam G., Lee D., Kim J., Kim J., Leem J.

Acta Physica Polonica A

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2012

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vol. 121

|

issue 1

214-216

EN

ZnO nanorods were grown by using the hydrothermal method on p-type Si (100) substrates with nanofibrous ZnO seed layers. Before the ZnO nanorods growth, nanofibrous ZnO seed layers were spin-coated onto the Si substrates. The structural and optical properties of ZnO nanorods were characterized by scanning electron microscopy, X-ray diffraction, and photoluminescence. The fibrous ZnO nanorods is possible due to the surface morphology of the nanofibrous ZnO seed layers. To investigate annealing effects of the ZnO nanorods, the post-annealing process was carried out at various temperatures ranging from 300 to 700C under argon conditions. The structural and optical properties of the ZnO nanorods were also affected by the post-annealing treatment.

17

Photoluminescence Properties of ZnO and ZnCdO Nanowires

80%

Zaleszczyk W., Fronc K., Aleszkiewicz M., Paszkowicz W., Wróbel J., Dłużewski P., Kret S., Klepka M., Kłopotowski Ł., Karczewski G., Wojtowicz T.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

357-362

EN

We report on the photoluminescence studies of ZnO and ZnCdO nanowires grown on SiO_2/Si substrates by low-pressure vapor phase synthesis. X-ray diffraction and transmission electron microscopy measurements show that the crystallographic structure of these ZnO and ZnCdO nanowires is of wurtzite-type with a high crystal perfection. Surface morphology of samples was determined by scanning electron microscopy and atomic force microscopy. The photoluminescence spectra of as-grown nanowires, nanowires extracted from the substrate and deposited onto Si wafer, and nanowires dispersed in ethanol by sonication were investigated at room temperature and compared to each other. The temperature dependence of the near band-gap photoluminescence emitted by the as-grown nanowires was also measured and analyzed.

18

Detector with High Internal Photocurrent Gain Based on ZnO:N

80%

Kosyachenko L., Lashkarev G., Ievtushenko A., Lazorenko V., Sklyarchuk V., Sklyarchuk O.

Acta Physica Polonica A

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2011

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vol. 119

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issue 5

681-682

EN

The photoresponsive structures prepared by magnetron sputtering of ZnO:N on p-Si substrates followed by vacuum evaporation of semi-transparent Ni film on ZnO surface were investigated. The mentioned structures show high sensitivity that sharply enhances with increase of applied voltage. Under a bias 5 V, the responsivities at λ = 390 and 850 nm are equal to 210 A/W and 110 A/W which correspond to the quantum efficiencies of 655 and 165, respectively. It is suggested that the observed high response is attributed to internal gain in phototransistor structure containing Ni/n-ZnO Schottky contact as emitter junction and n-ZnO/p-Si heterostructure as collector junction.

19

Fabrication, Structural Characterization and Optical Properties of the Flower-Like ZnO Nanowires

80%

Feng L., Liu A., Ma Y., Liu M., Man B.

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issue 3

512-517

EN

Multipod flower-like zinc oxide (ZnO) nanowires have been successfully synthesized on Si(111) substrates using a pulsed laser deposition prepared Zn film as "self-catalyst" by the simple thermal evaporation oxidation of the metallic zinc powder at 850°C without any other catalysts or additives. The pre-deposited Zn films by pulsed laser deposition on the substrates can promote the formation of the ZnO nuclei effectively. Also it can further advance the growth of the flower-like ZnO nanowires accordingly. X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, Fourier transform infrared spectrum, and photoluminescence were used to analyze the structure, morphology, composition and optical properties of the as-synthesized products. The results demonstrate that the nanowires were single crystalline with hexagonal wurzite structure, grown along the [0001] in the c-axis direction. Room temperature photoluminescence spectrum of the ZnO nanowires shows a nearband-edge ultraviolet emission (peak at ≈ 384 nm) and a deep-level green emission (peak at ≈ 513 nm). In addition, the growth mechanism of the flower-like ZnO nanowires is discussed in detail.

20

Study of the Clusterization of CdO Phase in ZnCdO Alloys by Modeling Fullerene-Like Zn₄₄Cd₄O₄₈ Cluster

80%

Ovsiannikova L., Kartuzov V., Shtepliuk I., Lashkarev G.

Acta Physica Polonica A

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2016

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vol. 129

|

issue 1a

A-41-A-43

EN

The structural, cohesive and electronic properties of fullerene-like isolated Zn₄₄Cd₄O₄₈ cluster with consideration of CdO phase clusterization are studied in the frames of density functional theory B3LYP/3-21G(d). It is revealed that an enlargement of CdO phase content in Zn₄₄Cd₄O₄₈ cluster leads to nonlinear rapid increase in cohesive energy and cluster stability, as well as band-gap energy shrinkage.

Refine search results

Effect of Substrate Temperature on the Structural and Optical Properties of Nanocrystalline Cadmium Selenide Thin Films Prepared by Electron Beam Evaporation Technique

Morphological Changes and Enhancement of Ultraviolet Emission by Subsequent Thermal Treatment of Ga-Doped ZnO Nanostructures

Surface Morphology, Structural and Optical Properties of MgO Films Obtained by Spray Pyrolysis Technique

Solubility and Segregation of Co in CdTe-Based Ternary and Quaternary Alloys

Raman Characterisation of Cd_{1-x}Zn_x Te Thick Polycrystalline Films Obtained by the Close-Spaced Sublimation

PVT-Grown Single Crystals of Cd_{1-x}Zn_{x}Te (x ≤ 0.25) and ZnTe as Substrates for Epitaxy

Properties of ZnO and ZnMnO Thin Films Obtained by Pulsed Laser Ablation

Epitaxial ZnO Films Grown at Low Temperature for Novel Electronic Application

Model and Properties of Fullerene-Like and Wurtzite-Like ZnO and Zn(Cd)O Clusters

Characterization of n-ZnO/p-GaN Heterojunction for Optoelectronic Applications

Properties of ZnO and Zn(Cd)O Fullerene-Like Clusters with a Shell of Diamond-Like Structure with sp^{2}/sp^{3} Bonds

The Investigation of the Cadmium Effect on Properties of ZnCdO Alloys Using Zn_{36-x}Cd_{x}O_{36} Clusters

CdSe/ZnSe Quantum Dots Formed by Low Temperature Epitaxy and In-Situ Annealing: Properties and Growth Optimization

High-Resolution X-Ray Diffraction Studies on MBE-Grown p-ZnTe/n-CdTe Heterojunctions for Solar Cell Applications

Enhancement of the Ultraviolet Luminescence Intensity from Cd-Doped ZnO Films Caused by Exciton Binding

ZnO Nanorods on Nanofibrous ZnO Seed Layers by Hydrothermal Method and Their Annealing Effects

Photoluminescence Properties of ZnO and ZnCdO Nanowires

Detector with High Internal Photocurrent Gain Based on ZnO:N

Fabrication, Structural Characterization and Optical Properties of the Flower-Like ZnO Nanowires

Study of the Clusterization of CdO Phase in ZnCdO Alloys by Modeling Fullerene-Like Zn₄₄Cd₄O₄₈ Cluster