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1.
The effect of oxygen partial pressure variation on the electrical conductivity and the optical transparency of CdO thin films, deposited through RF magnetron sputtering were studied in detail. Thin films of CdO have been deposited through radio frequency magnetron sputtering of a prefabricated CdO target at a fixed pressure 0.1 mbar and at a substrate temperature 523 K. It was found that the electrical conductivity of the CdO films could be varied over three decades for a variation of oxygen partial pressure of 0–100%, without introducing any extrinsic dopants. X-ray diffraction (XRD) studies showed that the films were polycrystalline in nature with a preferential orientation along (1 1 1) plane. Compositional information was obtained by X-ray photoelectron spectroscopic studies. This wide range of variation of electrical properties was explained through the oxygen vacancies formation.  相似文献   

2.
Here, a specific metal oxide (CuO) and its impurity (Cr) added composites were grown onto glass substrates as nanostructured thin films by executing ultrasonic spray pyrolysis method. The effects of the varied Cr dopant concentration on the morphological, structural, optical and H2 gas sensor properties of the synthesized CuO thin films were determined by conducting scanning electron microscopy, X-ray Diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, ultraviolet–visible spectroscopy, and gas detection analyses. The X-Ray Diffraction analysis revealed the presence of CuO crystals with predominant (111) plane and it changed to (002) orientation for the doped samples, where crystallite sizes varied between 32 and 46 nm. The structural studies disclosed that the crystalline structure modified due to the added impurities. The scanning electron microscopy observations unveiled polyhedron-like shape formations of the synthesized nanostructures which also showed clear indications of changed morphology due to the impacts of different Cr doping percentages. Besides, the presence of copper, oxygen, and chromium was confirmed by EDX elemental analysis as well as X-ray photoelectron spectroscopy. The optical examination concluded that absorbance values followed a random trend with respect to the increased impurity contents while bandgap decreased with the increase of doping concentration. And, it was also noted that the luminescent emission peaks decreased in the photoluminescence spectroscopy as a result of introduced impurity levels. Finally, H2 responsivity was detected for the grown films and found out that the impurity doping notably increased the sensitivity of the gas sensor based on the prepared CuO nanostructures.  相似文献   

3.
The goal of this study has been to investigate the influence of various post-deposition heat treatments on the microstructure, electrical and optical properties of In2O3:Sn (ITO) thin films deposited by electron beam evaporation. We have shown that electron beam evaporated ITO thin films deposited onto substrates kept upto 150 °C, have poor electrical properties and low optical transmission in the visible range, due to their amorphous structure. As the microstructure changes from amorphous to polycrystalline it was observed that the film resistivity decreases and it is simultaneously related to an improvement in the optical transmission. From comparisons of several annealing processes it has been observed that oxygen plays an important role in doping as well as the presence of Sn in the target material. Furthermore we have shown that high quality ITO thin films can be reproducibly prepared with optical transmission being enhanced by an annealing in air and the electrical characteristics being improved by a further annealing in a reducing atmosphere. Superior electrical and optical properties could be correlated with annealed films that exhibited a cubic bixbyte structure and large crystallite dimensions larger than 50 nm.  相似文献   

4.
A.A. Dakhel 《Solar Energy》2012,86(1):126-131
A comprehensive structural, optical, electrical, and optoelectronic study of arsenic-doped SnO2 was conducted. Several arsenic-doped SnO2 thin films with different arsenic content have been prepared on glass and silicon substrates by a vacuum thermal evaporation technique. The structural, electrical and optical study show that some of As5+ ions occupied locations in interstitial positions of SnO2 lattice. The prepared oxidized pure tin film is found to be consisting of orthorhombic and tetragonal SnO2 structure. The optical properties show that arsenic-doped SnO2 films are good transparent oxides. The bandgap of arsenic-doped SnO2 varies with arsenic content following the Moss–Burstein rule. The electrical behaviors show that the prepared arsenic-doped SnO2 films are degenerate semiconductors and might transform into insulators with increasing arsenic doping level. The electrical properties (resistivity, mobility, and carrier concentration) vary depending on the arsenic doping level. The SnO2 film doped with wt. 0.6% arsenic shows utmost dc electrical conductivity parameters: resistivity of 4.6 × 10?2 Ω cm, mobility of 6.0 cm2/V s, and carrier concentration of 2.25 × 1019 cm?3. From transparent-conducting-oxide (TCO) point of view, low arsenic concentration (less that 1%) is effective for SnO2 donor doping but not emulate doping with other dopant like Sb.  相似文献   

5.
Copper indium diselenide polycrystalline thin films of p-, i- and n-type electrical conductivity were grown using a one-step electrodeposition process in a single bath. The bulk structure and the stoichiometry of the layers were determined using X-ray diffraction and X-ray fluorescence. The material composition was correlated with the electrical conductivity type variation, detected by the photoelectrochemical cell. Atomic force microscopy analysis showed copper-rich films deposited at low cathodic potentials (0.6 V vs Ag/AgCl) are of spherical and granular morphology and the grain sizes were 0.3–0.5 μm, while stoichiometric CIS films deposited at 1.0 V vs Ag/AgCl have grain sizes of 0.1–0.4 μm. The initial studies of optoelectronic properties (Voc, Jsc and FF) of the four-layer solar cell devices (glass/FTO/n-CdS/n-CIS/i-CIS/p-CIS/Au) are presented.  相似文献   

6.
Indium-doped zinc oxide thin films were deposited on glass substrates by the chemical spray technique. Hydrated zinc 2,4-pentanedionate was used as zinc source. Four different indium compounds were separately used as dopants (indium nitrate, indium sulfate, indium acetate, and indium chloride). The effect of the thickness on the electrical, structural, morphological and optical characteristics of ZnO:In thin films was studied. Electrical resistivity values corresponding to good conductive electrodes were obtained irrespective of the indium compound used, although a decrease in electrical resistivity is found in all the cases as the film thickness increases, reaching a saturation value of 2×10−3 Ω cm. All films were polycrystalline with a wurtzite phase, and exhibited a (1 0 1) preferential orientation almost irrespective of neither the doping source nor thickness. The surface morphology was analyzed by scanning electron microscopy and a strong dependence on the indium compound and thickness was found, since grain geometry variations from rounded to rod-like forms were observed. As the film thickness increases, the film transmittance and the band-gap values decrease. Band-gap energy values were in the range of 3.21 to 3.44 eV.  相似文献   

7.
Copper indium selenide thin films were prepared through a novel and an eco-friendly selenisation process. In this method, selenium film required for selenisation was prepared using chemical bath deposition technique, at room temperature. Thus, totally avoided usage of highly toxic H2Se or selenium vapour. Here, the process involved annealing the Stacked layer, Se/In/Cu in which Cu and In were deposited using vacuum evaporation technique. Investigations on the solid-state reaction between the layers were done by analysing structural and optical properties of films formed at different annealing temperatures. Optimum annealing condition for the formation of copper indium selenide thin film was found to be 673 K for 1 h in high vacuum. Compositional dependence of the growth process was also studied using various Cu/In ratios. Optical band gap was decreased with increase in Cu/In ratio. Carrier concentration and hence conductivity were found to be increased with increase in Cu/In ratio. The films obtained were p-type and highly Cu-rich films were degenerate.  相似文献   

8.
The chemical bath deposition method was used to deposit thin films of cuprous oxide. The effect of copper source and triethanolamine content on the optical, morphological, structural, electrochemical and photoelectrochemical properties of the thin films for the development of photocathodes for hydrogen production was investigated. Triethanolamine promotes the complexing of Cu+ ions independent of the copper source used, its increase promotes thicker films due to better growth control and reduction of rapid Cu2O precipitation in the bulk solution. The increase in thickness promoted a change in preferential orientation from (111) plane to (200) plane, which also influenced and reduced the conductivity because there is a decrease in disorder (Urbach energy EU). The thickness also varied due to copper source used, reaching the thickest films with copper nitrate while the thinnest films with copper acetate, this tendency is in agreement with their solubility in water. The lower solubility reduces the complexing of Cu + ions which promotes the Cu2O precipitation in the bulk solution, limiting the growth of the film. Also, electrical properties varied (measured as disorder EU) with copper source. The most conductive being the thin films deposited with copper acetate and nitrate while the most resistive being the films deposited with copper sulphate. Very little variation in optical properties was observed, estimating the band gap in the range of 2.62–2.66 eV, while high absorption coefficient (>105 cm?1) was calculated below the absorption edge (460–470 nm). All thin films showed p-type semiconducting behavior with a flat band potential in the range of ?0.10 to 0.18 V (Ag/AgCl sat electrode), which confirms their ability to work as photocathodes for hydrogen production. The best photoelectrochemical performance was observed with the thinnest films, which also are the most conductive and present the highest values of absorption coefficient.  相似文献   

9.
This paper deals with a study on the effect of 120 MeV Ag9+ ion irradiation on photoelectrochemical properties of SrTiO3 thin films deposited on Indium doped Tin Oxide (ITO) coated glass by sol-gel spin-coating technique. The structural evolution in the pristine and irradiated films was determined by X-ray diffraction and X-ray photoelectron spectroscopy. Surface morphology was studied by Atomic Force Microscopy (AFM) and optical measurements were done by UV-visible absorption spectroscopy. Irradiation of SrTiO3 thin films was found to be effective in improving its photoelectrochemical properties. A noticeable decrease in the average grain diameter from 36 to 26 nm, reduction in bandgap from 3.55 to 3.43 eV and increase in roughness after irradiation contributed in enhancing photoelectrochemical activity of SrTiO3 thin films. Thin films irradiated at fluence 3 × 1012 ions cm−2, when used in PEC cell exhibited enhanced photocurrent of 0.16 mA cm−2 at zero bias conditions, which was four times higher than that of the unirradiated sample.  相似文献   

10.
The electrical and optical properties of pulsed laser deposited amorphous indium tin oxide films at room temperature are discussed. The films were grown from indium oxide (In2O3) targets of different tin (Sn) doping content (0, 5 and 10 wt%) at different oxygen pressures (PO2) ranging from 1×10−3 to 5×10−2 Torr. The electrical and optical properties of the films were examined by Hall measurements and optical spectrophotometry. It was found that high conductivity amorphous films could be prepared at room temperature irrespective of the Sn doping content. The properties of these films deposited from 0, 5, 10 wt% Sn-doped In2O3 targets show a similar response to changes in PO2. The maximal conductivity of (4.0, 2.1 and 1.8)×103 S/cm and optical transmittance (visible) higher than 90% were obtained at PO2 region of (1–1.5)×10−2 Torr. An undoped In2O3 film produced the highest conductivity of 4×103 S/cm in these studies.  相似文献   

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