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PL
W pracy przedstawiono wyniki badań wpływu wygrzewania na właściwości cienkich warstw tlenków wanadu (VxOy) wytworzonych metodą rozpylania magnetronowego. Cienkie warstwy bezpośrednio po naniesieniu oraz po wygrzewaniu w 200°C zostały poddane badaniom strukturalnym, optycznym oraz elektrycznym. Współczynnik transmisji cienkich warstw po wygrzewaniu zmniejszył się z około 70% na 50%. Z kolei rezystywność cienkiej warstwy tlenku wanadu po naniesieniu wynosiła 3.4·10⁴ Wcm, natomiast powłoki po wygrzaniu 1.6·10² Wcm. Badania współczynnika Seebecka wykazały, że wraz ze wzrostem różnicy temperatury między kontaktami elektrycznymi następuje zmiana typu przewodnictwa z dziurowego na elektronowy, a wygrzanie warstwy spowodowało uwydatnienie elektronowego typu przewodnictwa.
EN
This paper provides the research results of the influence of the post-process annealing of vanadium oxide (VxOy) thin films deposited by magnetron sputtering on their properties. As-deposited and annealed at 200°C thin films were analysed by means of their structural, optical and electrical properties. The transmission of thin films after annealing decreased from ca. 70% to 50%. In turn, the resistivity of the vanadium oxide thin films was equal to 3,4·10⁴ Wcm, while after post-process annealing it decreased to 1.6·10² Wcm. The studies of the Seebeck coefficient showed that with the increase of the temperature difference between the electrical contacts, the type of conductivity changes from hole to electron type, while the annealing of the layer enhances the electronic type of conductivity.
EN
The electronic, optical and thermoelectric properties of MoS2 nano-sheet in presence of the ru impurity have been calculated by density functional theory framework with generalized gradient approximation. The MoRuS2 nano-sheet electronic structure was changed to the n-type semiconductor by 1.3 eV energy gap. The optical coefficients were shown that the loosing optical energy occurred in the higher ultraviolet region, so this compound is a promising candidate for optical sensing in the infrared and visible range. The thermoelectric behaviors were implied to the good merit parameter in the 100K range and room temperatures and also has high amount of power factor in 600K which made it for power generators applications.
EN
In this article, synthesis, electronic and optical properties of an N-cyclohexyl-acrylamide (NCA) molecule are described based on different solvent environments and supported by theoretical calculations. Theoretical calculations have been carried out using a density function theory (DFT). Temperature dependence of the sample electrical resistance has been obtained by a four-point probe technique. Experimental and semitheoretical parameters such as optical density, transmittance, optical band gap, refractive index of the NCA for different solvents were obtained. Both optical values and electrical resistance values have shown that NCA is a semiconductor material. The values of HOMO and LUMO energy levels of the headline molecule indicate that it can be used as the electron transfer material in OLEDs. All results obtained confirm that the NCA is a candidate molecule for OLED and optoelectronic applications.
4
EN
Zinc oxide (ZnO) thin films were deposited on Si (1 0 0) and glass substrates by sol-gel spin coating technique. Zinc acetate dihydrate, monoethanolamine and isopropanol were used as the sources for precursor solution and the resulting gel was used for the preparation of ZnO thin films. The films were annealed at different temperatures (100 °C to 500 °C) and the effect of annealing on the structural and optical properties was investigated. X-ray diffraction (XRD) and UV-Vis spectroscopy were used for the analysis of the films. The XRD results indicated the polycrystalline hexagonal structure of the ZnO films with (0 0 2) orientation. The optical properties of the films were studied using UV-Vis spectrophotometer in the wavelength range of 190 – 1100 nm. The optical characterization of the ZnO thin films showed the high transmittance of ~90 % for the films annealed at 400 °C. The films showed the absorbance ~360 – 390 nm and bandgap values of 3.40 – 3.10 eV, depending on the annealing temperature of the films.
EN
MoO3 films were deposited by RF magnetron sputtering technique on glass and silicon substrates held at 473 K by sputtering of metallic molybdenum target at an oxygen partial pressure of 4 x 10-2 Pa and at different sputtering pressures in the range of 2 Pa to 6 Pa. The influence of sputtering pressure on the structure and surface morphology, electrical and optical properties of the MoO3 thin films was studied. X-ray diffraction studies suggest that the films deposited at a sputtering pressure of 2 Pa were polycrystalline in nature with mixed phase of α- and β-phase MoO3, while those formed at sputtering pressure of 4 Pa and above were of a-phase MoO3. Scanning electron micrographs showed a decrement in the size of the particles and their shapes changed from needle like structure to dense films with the increase of sputtering pressure. Fourier transform infrared spectroscopic studies confirmed the presence of characteristic vibration modes of Mo=O, Mo–O and Mo–O–Mo related to MoO3. Electrical resistivity of the MoO3 films decreased from 6.0 x 104 Ωcm to 2 X 104 Ω∙cm with an increase of sputtering pressure from 2 Pa to 6 Pa, respectively. Optical band gap of the films decreased from 3.12 eV to 2.86 eV with the increase of sputtering pressure from 2 Pa to 6 Pa, respectively.
6
Content available remote Plasmonic nanostructures of SnO2:Sb thin film under gamma radiation response
EN
This paper is a part of a natural dye solar cell project. Conductive transparent oxide (CTO) films have been deposited onto preheated glass substrates using a spray pyrolysis technique. The optical, electrical, structural properties as well as thermal annealing and gamma radiation response were studied. The average optical energy gap of doped films for direct allowed and direct forbidden transitions were found to be 3.92 and 3.68 eV, respectively. The plasmon frequency and plasmon energy after doping were found to be 3.48 x 1014 s-1 and 0.23 eV. The negative absorbance of the doped film was observed in UV-Vis range after applying both thermal annealing and ϒ-dose irradiation with 22 kGy. The negative refractive index of the doped film in UV range (220 – 300 nm) is promising for optical applications. The electron mobility μe reached a maximum of 27.4 cm2·V-1·s-1for Sb concentration of 10 %. The corresponding resistivity ρ and sheet resistance Rs reached their minimum values of 1.1 x 10-3 Ω·cm and 35 Ω·sq-1, respectively. The dopant concentration has been increased from 4.13 x 1019 to 2.1 x 1020cm-3. The doped film was found to exhibit three diffraction peaks associated with (2 2 2), (2 0 0), and (2 1 1) reflection planes, of which the peak of (2 2 2) of Sb2O3 and the peak of (2 0 0) were very close.
EN
The structural, electronic and optical properties of (AlSb)m/(GaSb)n (m-n: 1-1, 2-2, 1-3 and 3-1) superlattices are investigated within the density functional theory (DFT) by using the last version of the first principles full potential linear muffin tin orbital method (FP-LMTO) as implemented in LmtART 7.0 code. The exchange and correlation potential is treated by the local density approximation (LDA) for the total energy calculations. Our calculations of the band structure show that the superlattices (n ≠ 1) have a direct band gap Γ-Γ. The optical constants, including the dielectric function ϵ(w), the refractive index n(w) and the reflectivity R(w) are calculated and discussed.
8
Content available remote First-Principles Calculation of Cr/S Co-doped Rutile TiO2
EN
The electronic structures and optical properties of pure, Cr, S single- and Cr/S co-doped rutile TiO2 were calculated by the first-principle plane wave pseudopotential method based on density functional theory. The calculated results indicate that the three different doping ways can lead to lattice distortion in the rutile TiO2 and introduce local electronic states in the forbidden band of TiO2. The local energy levels in the forbidden band of TiO2 are mainly contributed by Cr-3d and S-3p orbital. Compared with pure TiO2, the absorption edges (i.e. the edge of the main peak) of the doped TiO2 have different blue shifts; however, the light response ranges of the doped systems are extended, especially in the case of Cr single- and Cr/S co-doped TiO2. The extension of the visible light response range of the doped TiO2 may enhance its visible light photocatalytic performance. In addition, the co-doped TiO2 has a stronger oxidation ability, which may increase the catalytic efficiency of TiO2.
EN
The development of transparent conducting oxide materials has gained an increased interest in the scientific community for developing efficient low cost optoelectronic devices. The effect of Cd precursor on structural and optical properties of sol-gel synthesized Zn0.9Cd0.1O nanostructured films has been studied by using XRD, AFM, optical absorption and emission spectroscopic techniques. X-ray diffraction confirms the hexagonal wurtzite crystal structure of the deposited films and the relative intensity of diffraction peaks has been observed with different cadmium salts. The granular surface morphology of the synthesized films has been observed from AFM measurements. The optical transmission, band gap and luminescence intensity was found to change for different cadmium salts. These results are very important for developing new materials for optoelectronic applications.
EN
We report a new direct fabrication of the ZnO nanorods (NR) by hydrothermal method, in which the preparation of seed layer is eliminated. We show that the tuning of initial temperature rate during the hydrothermal process plays a key role in the structural modification of the ZnO NR. A highly oriented ZnO NR is successfully fabricated by using a low rate of initial temperature. The increase of optical absorption and electron transport was obtained by reducing the diameter and increasing distribution of the ZnO NR on the substrate. Interestingly, an additional absorption from the defects is obtained in the system, which plays an important role in expanding the optical absorption. Our system will provide a favourable characteristic for developing the high-performance optoelectronic devices with high optical absorption and high electron transport.
EN
β-Ni(OH)2/ZnO composite powders were successfully synthesized by hydrothermal method at 180 °C for 15 h whereas NiO/ZnO composite powders formed after the as-prepared powders were calcined at 800 °C for 1 h in air. The X-ray diffractometer (XRD), scanning electron microscope (SEM), UV-Vis spectrophotometer were used to characterize the phase, particle shape as well as size and optical properties, respectively. In this system, it was found that ZnO is a major phase while β-Ni(OH)2 and NiO are a minor phases. The altered particle shape of ZnO was influenced by addition of Ni(CH3COO)2ˑ6H2O whereas the particle shape of the minor phase was changed due to the calcination process. The optical band gap decreased when the amount of minor phase increased. For photocatalytic study, it was found that 6 mol% β-Ni(OH)2/ZnO composite powders exhibited the best decolorization of methylene blue aqueous solution.
EN
The aim of this work was to produce a thin SnO2 film by a technique combining the sol-gel method and electrospinning from a solution based on polyvinylpyrrolidone and a tin chloride pentahydrate as a precursor. The spinning solution was subjected to an electrospinning process, and then the obtained nanofiber mats were calcined for 10 h at 500°C. Then, the scanning electron microscopy morphology analysis and chemical composition analysis by X-ray microanalysis of the manufactured thin film was performed. It was shown that an amorphous-crystalline layer formed by the SnO2 nanofiber network was obtained. Based on the UV-Vis spectrum, the width of the energy gap of the obtained layer was determined.
EN
In this work, we have prepared new materials of the nickel sulfide thin films by using the spray pyrolysis technique for promising co-catalyst to improve the photocatalytic performance or superconductivity. The effect of deposition temperature (523, 573 and 623 K) on structural, optical and electrical properties was investigated. The XRD diffraction shows that the prepared nickel sulfide at 523, 573 and 623 K having an orthorhombic, hexagonal and hexagonal structure, which were Ni3S2, Ni17S18 and NiS2, respectively. The minimum value of crystallite size (45,9 nm) was measured of deposited film at 573K. The thin films prepared at 523 and 573 K have an average transmittance is about 20 %. The prepared Ni1S2 thin film at T=623 K has the lowest calculated optical band gap and Urbach energy. The Ni1S2 thin film also has the best calculated of the refractive index and the extinction coefficient. The FTIR spectrums of the nickel sulfide have various bands such as Ni-S, C-H, O-H, N–H and C-S. The maximum electrical conductivity is 4,29x105 (Ω.cm)-1 was obtained at 573K of the Ni17S18. The nickel sulfide thin films sprayed at 573K have good structural, optical and electrical properties.
EN
We investigate an influence of the various crystal structure imperfections on the electronic properties and dielectric functions for In0.5Tl0.5I semiconductor in the frame of the density functional theory calculations. The tensor of electron effective mass m*ij of InI, In0.5Tl0.5I and TlI crystals has been calculated for the valence and conduction bands and different K-points of Brillouin zone. Dielectric functions ε(hν) of the defective crystals based on In0.5Tl0.5I solid state solution with iodine vacancy and thallium interstitial atom were calculated taking into consideration the inter-band and intra-band electron transitions. The studies of the defective crystals reveal increased low-frequency and stationary electron conductivity with anisotropy resulted from the anisotropy of the electron effective mass tensor. Our findings explain the origin of crucial changes in the band structure by formation the donor half-occupied levels close to the unoccupied conduction bands due to the crystal structure defects, i.e. iodine vacancy or thallium interstitial atom. It has been shown that in the case of real crystals, in particular metal-halides, the proper consideration of defects in quantum-chemical calculations results in a better matching of the theoretical and experimental results in comparison to the case when the perfect crystal structure had been used for calculations.
PL
Zbadano wpływ różnych niedoskonałości struktury krystalicznej na właściwości elektronowe i funkcje dielektryczne półprzewodnika In0.5Tl0.5I w ramach teorii funkcjonału gęstości. Został obliczony tensor efektywnej masy elektronów m* kryształów InI, In0.5Tl0.5I i TlI dla pasm walencyjnych i przewodnictwa oraz różnych K-punktów strefy Brillouina. Funkcje dielektryczne ε(hν) domieszkowanych kryształów roztworów stałych In0.5Tl0.5I z wakansami jodu i atomami międzywęzłowymi talu zostały obliczone z uwzględnieniem międzypasmowych i wewnątrz-pasmowych przejść elektronowych. Badania domieszkowanych kryształów ujawniły zwiększoną przewodność elektronową niskoczęstotliwościową i stacjonarną o anizotropii wynikającej z anizotropii tensora efektywnej masy elektronów. Przeprowadzone badania wyjaśniają obserwowane duże zmiany struktury pasmowej pochodzące z utworzenia pół wypełnionych poziomów donorowych w pobliżu niezajętych pasm przewodnictwa wynikających z defektów struktury krystalicznej, tj. wakansów jodu czy atomów międzywęzłową talu. Wykazano, że w przypadku kryształów rzeczywistych, w szczególności halogenków metali, właściwe uwzględnienie defektów w obliczeniach kwantowo-chemicznych daje możliwość lepszego dopasowania obliczeń teoretycznych do wyników doświadczalnych w porównaniu do obliczeń bazujących na strukturze krystalicznej doskonałej.
EN
A state-of-the-art fabrication of Y2O3 transparent ceramic by arc plasma synthesis using commercial micron-size powders is reported. The morphological observations of the surface by scanning electron microscope shows that a dense microstructure can be obtained. Arc melted samples are made of a white core and transparent layer. X-ray diffraction studies and also Raman spectroscopy confirm that only one phase occurred in the core and in the transparent layer, and that the physicochemical difference exists. The obtained Y2O3 shell ceramics have pores but also relative low absorbance in the VIS-NIR region after double side polishing. The optical band gap and the refractive index are reported. It is concluded that arc plasma melting allows obtaining quickly (10 minutes) dense and highly transparent polycrystalline samples, especially in the VIS-IR spectral region.
EN
We proposed to design a tunable multichannel optical filter composed of uniaxial indefinite metamaterial and dielectric photonic crystal categories arrangement, which can be employed as a valuable variation of peak transmission in microwave frequency. Because of the optical axis and polarization dependence of the uniaxial metamaterial layer, the position trend in the multichannel optical filter is shown to also rely on both TE and TM polarizations. The numerical results show that by changes of the incidence angle, width of photonic band gap (PBG) compacts (widens) at TE (TM) polarization and the PBG of the structure shifts towards the higher frequency region, for both polarizations. In addition, the multichannel optical filter properties and shift trend of the PBG are also affected by changing the optical axis of the uniaxial indefinite metamaterial. Thus, results shown that without appending defect layer in this structure, the sets of comb-like resonant peaks in transmission modes can be utilized in the lower or higher band edge of PBG at TE and TM polarizations.
17
Content available remote Thin film characterization of Ce and Sn co-doped CdZnS by chemical bath deposition
EN
Cerium and tin co-doped cadmium zinc sulfide nanoparticles (CdZnS:Ce)Sn were synthesized by chemical bath deposition method with a fixed concentration of Ce (3.84 mol%) and three different concentrations of Sn (2 mol % and 4 mol% and 6 mol%). They showed broad photoluminescence spectra in the visible region under the ultraviolet excitation with a wavelength of 325 nm. The photoluminescence emission peaks were obtained at 540 nm, 560 nm and 570 nm for CdZnS, CdZnS:Ce and (CdZnS:Ce)Sn thin films, respectively having different concentrations of Sn. It has been observed that the photoluminescence emission peak shifted to higher wavelength region with an increase in intensity by Ce doping and Ce-Sn co-doping. Further enhancement in luminescence peak intensity has been observed by increasing concentration of Sn in (CdZnS:Ce)Sn films. Average crystallite size, measured from XRD data, was found to be increased with increasing concentration of Sn. An increase in the concentration of Sn shifted the UV-Vis absorption edge toward the higher wavelength side. Energy band gap for undoped CdZnS and Ce-Sn co-doped CdZnS varied from 2.608 eV to 2.405 eV. The SEM micrographs of CdZnS and (CdZnS:Ce)Sn films showed the leafy-like and ball-like structures. The presence of Sn and Ce was confirmed by EDAX analysis.
EN
Diamond-like carbon (DLC) films were electrochemically deposited onto indium tin oxide (ITO) substrates using acetic acid and deionized water as electrolyte at low deposition voltages (2.4 V and 60 V). The transmittance of the films was investigated by UV spectrometry. Transmittance measurements versus wavelength revealed that the films transmit 86 % to 89 % light in visible region and band gap of the films varies between 3.87 eV and 3.89 eV. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used for structural characterization to evaluate surface morphology of the DLC films. The grain size and the surface roughness increased for the films prepared at higher deposition potential, while their measured average height decreased. The mechanical properties (hardness H and elastic modulus Er) were determined from load-displacement curves which were obtained by using nanoindentation method. Hardness and elastic modulus of the films increased as the deposition voltage of the films increased from 2.4 V to 60 V.
EN
An inorganic coordination complex of single crystal containing sodium and aluminum (SA) was grown at room temperature by slow evaporation technique. The crystal was characterized using single crystal X-ray diffraction (XRD), FT-IR, UV-Vis, SHG, SEM, EDX and TG/DTA analyses. The size of the grown crystal was around 17 mm × 15 mm × 5 mm. Both optical and SEM photographs confirmed that the crystal is transparent with smooth surface. The XRD data showed that the crystal belongs to the BCC crystal structure. The crystal shows excellent transparency in the entire region of visible light (cut-off value is 339 cm−1 ). The dielectric constant as well as dielectric loss of the sample was calculated by varying frequencies at different temperatures and the presence of low dielectric loss proved that this crystal can be used for the NLO application.
20
EN
Structural, morphological, optical and electrical characteristics of zinc sulfide (ZnS) and boron doped zinc sulfide (ZnS:B) films deposited on glass substrates by ultrasonic spray pyrolysis (USP) method and heated up to 350±5 °C were studied. B doping at various concentrations did not change the crystal structure of the ZnS film and it also did not cause any significant change in the size of crystallites. Maximum transmittance values of the B doped ZnS films increased parallel to doping rate. Transmittance edges showed shifting towards smaller wavelengths due to the effect of B doping. B doping increased optical band gap values. Scanning electron microscopy (SEM) images of the film surfaces showed that B doping did not cause any significant change in grain sizes of the films. Presence of all expected elements in the films including Zn, S and B was confirmed through Energy Dispersive Spectrometry (EDS) analysis. Significant peaks of foreign phases on the film surfaces were observed through Fourier Transform Infrared (FT-IR) spectroscopy. The electrical resistivity values of the films were calculated by means of current-voltage characteristics.
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