scholarly journals Forming of CdZnTe thin films grown by hot wall epitaxy and their properties

2021 ◽  
Vol 22 (4) ◽  
pp. 638-643
Author(s):  
M. Vuichyk ◽  
L. Rashkovets’kyi ◽  
S. Lavoryk ◽  
P. Lytvyn ◽  
K. Svezhentsova
Keyword(s):  
Absorption Edge ◽  
Self Organization ◽  
Optical Studies ◽  
X Ray ◽  
Small Crystals ◽  
Substrate Temperatures ◽  
Film Absorption ◽  
Gap Width ◽  
Hot Wall Epitaxy ◽  
Band Gap Width

In this work morphological, X-ray structural and optical studies of CdZnTe films grown by hot wall epitaxy method at relatively low substrate temperatures were performed. Possible mechanisms and processes of self-organization that occur during the growth of such structures are considered. It is shown that at thickness of film more than 130 nm on the surface, large (lateral size 150 - 200 nm, height - up to 10 nm) and small crystals are observed. The thicknesses and energy of the band gap width of the CdZnTe films grown at different growth times were determined. It is shown that the film absorption edge in the transmission spectra depends on the film thickness and the reasons for the shift of the film absorption edge are discussed.

scholarly journals Прозрачные фотоактивные ZnO-MgO-Ag-=SUB=-2-=/SUB=-O-покрытия на стеклах

2019 ◽  
Vol 127 (8) ◽  
pp. 292
Author(s):  
С.К. Евстропьев ◽  
Н.В. Никоноров ◽  
В.М. Киселев ◽  
А.C. Саратовский ◽  
Е.В. Колобкова
Keyword(s):  
Electron Microscopy ◽  
Optical Properties ◽  
Visible Spectral Region ◽  
X Ray Diffraction ◽  
Oxide Coatings ◽  
High Transparency ◽  
X Ray ◽  
Gap Width ◽  
Band Gap Width ◽  
Scanning Electron

AbstractTransparent ZnO–MgO–Ag_2O coatings are formed on glasses by the polymer–salt method, and the optical properties of these coatings are studied. The optical properties of the films are studied by optical spectroscopy and photoluminescence. The structure of the oxide coatings is studied by X-ray diffraction analysis and scanning electron microscopy. It is found that an increase in the silver concentration in the coatings leads to a decrease in the band gap width of the material. It is shown that the films are characterized by a high transparency in the visible spectral region and can generate singlet oxygen under action of UV radiation (370 nm) and blue light (405 nm).

scholarly journals Влияние рентгеновского излучения на оптические свойства фоторефрактивных кристаллов силиката висмута

2019 ◽  
Vol 53 (8) ◽  
pp. 1043
Author(s):  
В.Т. Аванесян ◽  
И.В. Писковатскова ◽  
В.М. Стожаров
Keyword(s):  
Optical Absorption ◽  
Single Crystals ◽  
Defect Structure ◽  
Urbach Energy ◽  
Optical Absorption Spectra ◽  
Characteristic Parameters ◽  
Bismuth Silicate ◽  
X Ray ◽  
Gap Width ◽  
Band Gap Width

AbstractThe results of investigations of the optical-absorption spectra of bismuth-silicate (Bi_12SiO_20) single crystals are presented. The band-gap width and the characteristic Urbach energy are determined. The effect of preliminary X -ray irradiation on the behavior of the experimental spectral dependences and the values of the characteristic parameters induced by the bismuth-silicate defect structure is established.

scholarly journals Ab initio calculation of the electronic structure of a solid solution of strontium-bismuth molybdat

2021 ◽  
Vol 2094 (2) ◽  
pp. 022043
Author(s):  
E V Sokolenko ◽  
E S Buyanova ◽  
Z A Mikhaylovskaya ◽  
G V Slusarev
Keyword(s):  
Solid Solution ◽  
Electronic Structure ◽  
First Principles ◽  
Ab Initio Calculation ◽  
Structural Data ◽  
Reflection Spectra ◽  
First Principles Calculations ◽  
X Ray ◽  
Gap Width ◽  
Band Gap Width

Abstract Scheelite-like compounds based on SrMoO4 have been studied. Based on X–ray structural data, models of Sr1-3xBi2xMoO4 structures (x=0.2125) are constructed, at x≧0.175, a superstructural ordering is observed associated with the location of cationic vacancies. From the first principles, calculations of the density of states in the vicinity of the forbidden zone are performed. The calculated values of the band gap width were compared with the values obtained from the reflection spectra.

scholarly journals Resistive switching and optical properties of strontium ferrate titanate thin film prepared via chemical solution deposition

2020 ◽  
Author(s):  
Jun Li ◽  
Xingui Tang ◽  
Qiuxiang Liu ◽  
Yanping Jiang ◽  
Zhenxun Tang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Band Gap ◽  
Strontium Titanate ◽  
Chemical Solution ◽  
Vacancy Defects ◽  
X Ray ◽  
Fe Ions ◽  
Gap Width ◽  
Band Gap Width

Abstract The polycrystalline strontium ferrate titanate (SrFe0.1Ti0.9O3, abbreviated to SFTO) thin films have been successfully prepared by chemical solution method. By analyzing the current-voltage (I-V) characteristics, we discuss the conduction mechanism of SFTO. It is found that the number of oxygen vacancy defects is increased by Fe ions doping, making SFTO be with better resistive switching property. Fe ions doping can also enhance the absorption of strontium titanate to be exposed to visible light, which is associated with the change of energy band. The band gap width (2.84 eV) of SFTO films is figured out, which is less than that of pure strontium titanate. Due to more oxygen vacancy defects caused by Fe ions doping, the band gap width of strontium titanate was reduced slightly. The defect types of SFTO thin films can be determined by electron paramagnetic resonance spectroscopy. In addition, we analyzed the energy band and state density of SFTO by first-principle calculation based on density functional theory, and found that Fe ions doping can reduce the band gap width of strontium titanate with micro-regulation on the band structure. A chemical state of SFTO was analyzed by X-ray photo electron spectroscopy. At the same time, the structure and morphology of SFTO were characterized by X-ray diffraction and scanning electron microscope. This study deepened the understanding of the influence of Fe ions doping on the structure and properties of strontium ferrate titanate, which is expected to be a functional thin film material for memristor devices.

scholarly journals Investigation of band gap width in mixed ZnSxSe1–x crystals

2018 ◽  
pp. 44-49
Author(s):  
O. G. Trubaieva ◽  
M. A. Chaika
Keyword(s):  
Band Gap ◽  
Sulfur Content ◽  
Mixed Crystals ◽  
Energy Structure ◽  
Absorption Region ◽  
High Optical Quality ◽  
X Ray ◽  
Γ Ray ◽  
Gap Width ◽  
Band Gap Width

Scintillators based on ZnSxSe1–x are promising materials for X-ray and γ-ray detection. For optoelectronic devices, it is better to use semiconductor compounds with a direct-zone energy structure with its spectral range lying in the fundamental absorption region. The band gap in such semiconductors is an important parameter that affects the energy resolution, ionization energy, dark current and other scintillation characteristics. The effect of sulfur content on the optical width of the band gap in mixed crystals ZnSxSe1–x is investigated in this paper. The test samples for this study were grown by Bridgman-Stockbarger in graphite crucibles with the diameter of 25 mm in the Ar atmosphere (PAr = 2∙106 Pa) at a temperature from 1870 to 2000 K, depending on the composition of the initial raw materials. Six samples with different content of components were obtained: ZnS0.07Se0.93, ZnS0.15Se0.85, ZnS0.22Se0.78, ZnS0.28Se0.72, ZnS0.32Se0.68, ZnS0.39Se0.61. The transmittance of the samples in the range from 61 to 67% at 1100 nm (sample thickness 4 mm) indicates a high optical quality of the crystals. It was established that the optical width of the band gap for mixed crystals ZnSxSe1–x increases from 2.59 to 2.78 eV with increasing sulfur content from 0.07 to 0.39 for direct transitions and from 2.49 to 2.70 eV for indirect transitions. A comparison was made between theoretical and experimentally obtained values of the band gap width. It is shown that no new (defective) levels appear in the band gap. The smooth dependence of the optical band gap on the composition indicate a possibility of growing ZnSxSe1–x mixed crystals by directional solidification techniques for X-ray and γ-ray detectors. The wider band gap and higer atomic mass ratio of ZnSxSe1–x crystals, as compared to ZnSe(Te) or/and ZnSe(Al) crystals, extend application areas of such semiconductor material

scholarly journals Resistive switching and optical properties of strontium ferrate titanate thin film prepared via chemical solution deposition

2021 ◽  
Author(s):  
Jun Li ◽  
Xingui Tang ◽  
Qiuxiang Liu ◽  
Yanping Jiang ◽  
Zhenxun Tang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Band Gap ◽  
Strontium Titanate ◽  
Chemical Solution ◽  
Vacancy Defects ◽  
X Ray ◽  
Ion Doping ◽  
Gap Width ◽  
Band Gap Width

AbstractThe polycrystalline strontium ferrate titanate (SrFe0.1Ti0.9O3, SFTO) thin films have been successfully prepared by chemical solution method. By analyzing the current-voltage (I–V) characteristics, we discuss the conduction mechanism of SFTO. It is found that the number of oxygen vacancy defects is increased by Fe ion doping, making SFTO be with better resistive switching property. Fe ion doping can also enhance the absorption of strontium titanate to be exposed to visible light, which is associated with the change of energy band. The band gap width (2.84 eV) of SFTO films is figured out, which is less than that of pure strontium titanate. Due to more oxygen vacancy defects caused by Fe ion doping, the band gap width of strontium titanate was reduced slightly. The defect types of SFTO thin films can be determined by electron paramagnetic resonance spectroscopy. In addition, we analyzed the energy band and state density of SFTO by first-principles calculation based on density functional theory, and found that Fe ion doping can reduce the band gap width of strontium titanate with micro-regulation on the band structure. A chemical state of SFTO was analyzed by X-ray photo electron spectroscopy. At the same time, the structure and morphology of SFTO were characterized by X-ray diffraction and scanning electron microscope. This study deepens further understanding of the influence of Fe ion doping on the structure and properties of strontium ferrate titanate, which is expected to be a functional thin film material for memristor devices.

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

X-Ray absorption edge elemental imaging of B. thuringienis

1989 ◽  
Vol 47 ◽  
pp. 212-213
Author(s):  
R. L. Stears
Keyword(s):  
Absorption Edge ◽  
Elemental Distribution ◽  
X Rays ◽  
Differential Absorption ◽  
Synchrotron Source ◽  
High Brightness ◽  
X Ray ◽  
Elemental Imaging ◽  
Cellular Integrity ◽  
X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

scholarly journals Modeling of the Resonant X-ray Response of a Chiral Cubic Phase

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 214
Author(s):  
Timon Grabovac ◽  
Ewa Gorecka ◽  
Damian Pociecha ◽  
Nataša Vaupotič
Keyword(s):  
Absorption Edge ◽  
Unit Cell ◽  
Resonant Peak ◽  
Cubic Phase ◽  
Tensor Form ◽  
Resonant Enhancement ◽  
X Ray ◽  
X Ray Scattering ◽  
Thermotropic Liquid Crystals ◽  
Carbon Absorption

The structure of a continuous-grid chiral cubic phase made of achiral constituent molecules is a hot topic in the field of thermotropic liquid crystals. Several structural models have been proposed so far. Resonant X-ray scattering (RXS), which gives information on the molecular orientation in the unit cell, could be applied to select the most appropriate model. We modeled the RXS response for the recently proposed chiral cubic phase structure with an all-hexagon chiral continuous grid. A tensor form factor of a unit cell is constructed, which enables calculation of intensities of peaks for all Miller indices. We find that all the symmetry allowed peaks are resonantly enhanced, and their intensity is much stronger than the intensity of the symmetry forbidden (resonant) peaks. In particular, we predict that a strong resonant enhancement of the symmetry allowed peaks (011) and (002), not observed in a nonresonant scattering, could be observed by RXS at the carbon absorption edge. By RXS at the sulfur absorption edge, one might observe a resonant peak (113) and resonantly enhanced peak (233), and resonant enhancement of all the peaks that are observed in a nonresonant scattering, which probably hide the rest of the predicted resonant peaks.

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